Dual Battery Time Again

[Babs]

I guys yes I know there is dozens of threads on the Dual Battery and I'm going to read up on them. In the meantime my auto electrician has showed me this


102588

I'm pretty sure I'm going to go with Redarc but what set up I am still to determine.

He is advising this unit with a 100-120 ah closed cell battery.

I will be running fridge mostly and was thinking about putting the winch on the auxiliary as well.

I wanted it to isolate from the main when the main battery drops below a certain level.

What are your thoughts on set up and what batteries and units are you running.

Cheers, I look forward to your replies.

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[drivesafe]

Hi Babs and this will probably start the usual debate, but Babs, what do you think you will gain by fitting a DC/DC device?

Because what you have posted up about what you want to do with your vehicle, means you are actually creating a lot of disadvantages by fitting one.

[Babs]

Hi Babs and this will probably start the usual debate, but Babs, what do you think you will gain by fitting a DC/DC device? Because what you have posted up about what you want to do with your vehicle, means you are actually creating a lot of disadvantages by fitting one.

Drivesafe I have no idea whatsoever when it comes to electrical. I have no idea what the unit is that I took the photo of, he is proposing this and I'm not doing anything until I get some advise of the forum here.

My last battery setups were done through the mechanic and trusted him to give me the right setup.

Please feel free to give me your thoughts on this, I appreciate all input. Cheers.

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[Homestar]

Hi Babs, there has been much heated discussions on this topic, but if you listen to the people that actually do these things for a living and understand batteries and how they charge - not just your local Autolec or Mechanic who are generally just dealers for these devices, then you will find that not only don't you need one, but you will also find that your auxiliary battery will take longer to charge. Your cars alternator is the best device to do this, and it's already there.

Do yourself a favour, have a chat to Tim (Drivesafe who answered your first post) - click the link in his signature - his number is there, then buy the system he recommends - he won't try and sell you something you don't need and his systems are unmatched in the industry. I run one in my L322 and it is brilliant, and does more than you might think. He backs his products and has first rate after sales service.

No, I have no association with him, but as an Electrician I understand more than a lot do on this subject and I've found his knowledge on the subject unmatched.

(Ok Tim, you can send me this months cheque now)... :D

[weeds]

I did have a traxide fitted to the fender......

Have now fitted 3 x basic rearc isolator a to the three work cars

[inside]

I did have a basic redcarc but the desert killed it. Now I use a Narva voltage sensitive relay , cost $44. This works fine for and keeps things simple.

[tonyf]

I was directed to Traxide (by Justinc) and from my experience with dual batteries in my TD5, fitted with a Traxide system, as well as from reading his posts in this forum, I don't think you can go wrong if you follow his advice.

[Babs]

Just waiting for Tim to recommend something.

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[drivesafe]

Hi folks, after a PM exchange with Babs, I'll post up the advantages and disadvantages of different types of Dual Battery Systems ( DBS ) for Babs, but this may be of assistance to others.

I'll will have to do it in sections as I am flat out filling orders, and if you have any questions or disagree with my posts, please feel free to reply.

DC/DC devices first. These devices are the most over rated form of battery charging.

The advertising for these devices claim they can charge a battery to 100%. They even imply or outright state that an alternator can not fully charge a battery to 100%.

While both claims are correct, both claims are an exaggeration, and for the very same reason.

If you have a low auxiliary battery, unless you drive long enough, then an alternator will not full charge that battery, but the same is the case when using a DC/DC device to charge that same battery.

Unless you drive long enough, there is also no way a DC/DC device can fully charge a low auxiliary battery. But this is something you never find in all the grossly exaggerated advertising and this is lying by omission.

The reality is that if you have a low auxiliary battery, you are highly unlikely to drive long enough to fully charge the battery, no matter what type of charging you use.

But depending on the type of battery and how low it is when you start your drive, an alternator can usually have a battery in a higher state of charge at the end of a drive than what a 20 amp DC/DC device can.

Using a 40 amp DC/DC device, then you can bring many batteries to a higher state of charge than an alternator can, but if the battery is something like an Optima, then an alternator will easily charge this type of battery up 40% quicker than even a 40 amp DC/DC device can.

If you are just topping up batteries, then a DC/DC device can in many cases, do it in a shorter drive time, but if you drive for periods of 3 three or more hours, an alternator will still achieve the same charging level.

The one situation where the use of a DC/DC device can be advantageous is where you have a setup that uses thin cabling for connection between the cranking battery and a battery in the rear of a vehicle, or in a caravan or camper trailer.

It would still be cheaper to replace the thin cabling with decent size cable but some situations do not allow for the changing of the cable size, so a DC/DC device can be a big improvement in charging capability.

[Babs]

Tim thank you for that.

So my next question is what do you recommend?

I'm still a little confused, do I get a 40 DCDC or do I connect to alternator?

What is BCDC I noticed the photo I posted was a BCDC not a DCDC?

Is there a device that connects up with alternator if that is the way to go?

Does it take charge away from main battery if hooked to alternator?

Oooh I am so confused ha ha ha

I want to run a fridge and winch and compressor, if I am camping for two days and fridge runs battery low will the winch still work?

What's the best way to set up to have a longer run time?

Signed, Hopeless clueless ha ha ha

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[weeds]

I want to run a fridge and winch and compressor, if I am camping for two days and fridge runs battery low will the winch still work?

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One would hope your winch would still work as its a general rule that your winch is wired to your start battery......if your winch ain't working than there is a good chance you engine isn't going to start......

Your fridge should be connected to your AUX battery which is separated from your start battery when you are at camp......this ensures you can still start you car.

Babs, where bouts do you live.....might be easier if somebody shows you there install......

[weeds]

If your last battery set up worked than install the same.

[Babs]

One would hope your winch would still work as its a general rule that your winch is wired to your start battery......if your winch ain't working than there is a good chance you engine isn't going to start...... Your fridge should be connected to your AUX battery which is separated from your start battery when you are at camp......this ensures you can still start you car. Babs, where bouts do you live.....might be easier if somebody shows you there install......

I think that's how all my last vehicles were set up, I'm just confusing myself.

I'm not using my old mechanic anymore so hence why I'm posting here.

I'll wait to see what Tim recommends

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[drivesafe]

Hi again Babs and my last post was part 1 of a 3 part reply to your questions.

The BCDC is just another name for a DC/DC device.

In Part 3 I will explain the best way to charge your batteries, all of them, and how the get the longest operating time for your fridge.

I will also give you details on the best way to setup for winching.

Sorry, I am a slow ( one finger ) keyboard typer so it takes me a while to get the replies typed and as posted, I am trying to get a lot of orders ready to go for Monday's mail.

[Babs]

All good Tim, I'll be patient

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[Blknight.aus]

I'll make it all simple

get a traxide from drive safe. prepare to hook it up.

fit the winch to the start battery with a good set of relays and a bypass solenoid for the traxide if you really think your going to torture it that much with the winch (you most likely wont).

get an auxiliary battery best suited for what you want to run off it,

Pick something deep cycle if you only want to run a fridge and some low wattage lighting
pick a dual purpose/hybrid if you're going to use inverters occasionally
pick a cranking battery if your going to use inverters a lot or expect to parallel them for winching


Hook your compressor up to either battery and always have the engine running when you use it, same for the winch. This is as much for the benefit of the batteries as it is for the winch and the compressor.

Thats it, as shortly, simple and cost effectively as I can put it for you.

some extra information for you...

the key difference and the new scenario where I might recommend a BCDC charger over a drive safe unit is this...

BCDC charges usually incorporate a solar input and regulator and allow, in some circumstances a significant cost saving over purchasing both a dual battery controller AND a solar regulator combined with the cost saving of lighter cabling and in some cases installation costs. Typically, in a situation like this the normal method of operation includes longer driving times and extended stationary times relying on the solar to top up the batteries which moots the 2 key difference between a traxide and a DC/DC charger

me Personally I wouldnt buy a BCDC or DCDC charger outside of 2 very specific sets of circumstances Id run a setup simlilar to a traxide (or get a traxide) and fit a seperate solar system, primarily because I get to the the install work my self my way and I can get the component pieces at a good price.

[Babs]

Still waiting to find out about these Traxides ???

I'll wait for Tim's next part reply.

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[Blknight.aus]

traxides?

best dual battery manager for more than 90% of situations.

in a nutshell in most circumstances they will get you the longest draw duration out of a pair of batteries and give you the shortest possible recharge time off of running the engine.

They have a few configuration options that are dead simple and are compatible with pretty much every vehicle from the T ford through to next years whatever they come up with.

if you have nothing to start with get this kit

Def-USI-FPC Kit | TRAXIDE - RV | Traxide - RV (http://traxide.com.au/complete-diy-dual-battery/land-rover-dbs-kits/defender-dbs-kits/def-usi-fpc-kit.html)

then its just a case of if desired adding aftermarket solar to the anderson plug or as I would recommend fitting the solar gear to your camper trailer and using that anderson plug to hook directly into the campers battery if fitted.

Just remember that for the very best results all your batteries should be the same technology or if your going to be using one in the camper that it should be the same type of battery as the aux battery in the vehicle.

about the only thing that drivesafe does different to me in his setups is his fusing and circuit breakers. I tend to use more of them and to use both fuses and circuit breakers. Double edged sword, My system is safer in a small percentage of worst case scenarios his system provides more flexability in about the same number of cases.

Everyone picks up on the fact that none of my vehicles have traxide units in them and thats because my battery system is setup to allow me to relatively easily provide 24v and his units cant handle what I have to do to achieve that.

[Blknight.aus]

heres how most dc/dc and BCDC chargers work.

you put it in wire it up and when the engine is running and the voltage is high enough it starts sucking down amps and doing white man magic to pump the voltage up to the charging voltage of for the aux battery at the limit of the unit, say 40A.

Remember entropy, it works for electricity every time you step it or conduct it you loose a little bit of the overall input.

at the end of the day with just a 10% loss you need 44A of draw to produce 40A of output (Its more complicated than that but that will do for here) and a little bit for the smarts.

a traxide doesnt do that fancy stuff and its also not limited to a paltry 40A it is for want of a simpler better explanation an exceptionally smart relay. what you put in on one side comes out the other. you still need a little bit for the smarts.

what a traxide does better than most DC/DC units is make use of the main battery. it leaves everything hooked up with essentially no losses and splits the load between the 2 batteries taking full advantage of peukurts rules on battery discharging. then it disconnects the main battery letting the aux battery take over. At this point compared to a DC/DC unit you're in front. not by much, maybe 10AH over a 24 hour period for me thats an extra 3 hours of cold beer potential. But Its still in front and at this point for the cost of a good 40A dc/DC you jsut bought the entire kit from my previous post. Thats Everything you need to install it to be able to run your frigde for an extra 3 hours.

so now lets get onto charging and here is where traxides shine.

your alternator can produce 100A and your 40A DCDC can push 40 to the aux battery, lets say its dead, and needs 100A to charge. the main battery is at 70% and needs 40Ah worth to charge it.

for the first 15 minutes the traxide will dump most of the charging current to the dead battery and some into the main battery this will taper across untill the charging current is equal to an even split and then it will stay evenly split but taper off. while the aux battery is flat the alternators output will be pegged at maximum wattage output and therefore maximum amps. lets say thats 100 amps and that your vehicle always draws 20 so you have 80 amps to charge with. To start with your charge might be 70A going to the aux and 10 going to the starting battery, they then balance down to 40A each and as the system voltage rises the amps drop off because thats how alternators charging batteries work. just to make up a time for the first hour your aux battery was getting more than 40 amps. a lot more to start with but then it tapers back.

lets look at DC/DC

you start up and the alternator starts to charge the main battery, its at 70% so its going to draw 40 Amps which is the same as the previous example, thats what it needed, thats what it took. Then after a minute or 2 the battery voltage comes up and the DC/DC kicks in (sometimes immediately so lets just say that it did that in this scenario) and begins to draw its 40 Amps from the main battery to put 40 amps into the aux battery (I'm being nice and ignoring entropy here in reality its drawing 44 to deliver 40 which means the main battery is now only getting 36A but I digress) 15 minutes later when the main battery is partially charged it doenst need 40A it wants 30, the DCDC is still working its guts out against the still nearly flat aux battery so is still pulling its 40Amps. the Main is pulling 30A, the aux 40. thats 70.

heres the stakes after 15ish minutes.. the traxide system still has the alternator pushing its limits 20amp to thevehicle and 80 to the batteries for charging. the DCDC has the same 20 amps going to the vehicle but only 70A going to the batteries. the bigger the alternator and the bigger the batteries the more pronounced the difference becomes.


Drivesafes goign to hate me for it but here it is..

these are the 3 circumstances when a DCDC or BCDC is better than a traxide.
1. when you need to shape or current limit the charge going to the aux batteries
2. when you need to step across voltages (12-24)
3. when you need to maintain a more stable voltage on the aux battery for sensitive equipment

if you're in one of those 3 catagories then you need a very specific DC DC charger and so far its been less than 10% of the cases ive ever had to do DBS installs in.

other than that... let your wallet make the decision for you.

from ebay for $460 (http://www.ebay.com.au/itm/Redarc-In-Vehicle-40A-DC-DC-Battery-Charger-MPPT-Regulator-BCDC1240-/201234514637?_trksid=p2141725.m3641.l6368) + postage you can have just the charge unit and then you have to pay for all the cable, fittings and installation.
From traxide for $445 + postage you can have the whole kit and then only have to spring for the install.

you might notice that the unit in ebay is also a solar capable unit. thats ok for the cost of the cabling, and the $15 difference you can buy a reasonable 10A solar regulator. which when plugged into the traxide system charges ALL of your batteries as opposed to only the aux battery. Before you note that you want more than 10A worth of panels, A, for just a car fridge no you dont and b, if your getting bigger panels than that most bigger panel setups you can get bundled with a regulator.

[weeds]

Still waiting to find out about these Traxides ???

I'll wait for Tim's next part reply.

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Search Traxide on this forum.....it will give you entry of reading.......Tim has probably explained it 100 times over

Or jump to the dark side and go with one of any quality products out there.......

[drivesafe]

Hi Dave and thanks for all that info, and while I agree with most of it, the difference between what you get in the way of available accessories battery capacity is quite a large amount more than you covered.

The advantages of using my systems is as you have posted, my systems are far gentler on the batteries, for the same amount of energy used, because my systems spread the load over at least two batteries.

But it doesn't end there.

Because my systems allow up to 50% of the cranking battery's capacity to be used to run your accessories, if you use the same amount of capacity as you would do with either a DC/DC unit or with Standard type Voltage Sensing Relay ( VSR ) Isolator, you will draw 50% less off both batteries and this has a number of very useful benefits.

Lets say you have a 100Ah auxiliary battery being recharged via a DC/DC device or Standard VSR.

You have a total usable capacity of 80Ah, which means your auxiliary battery will be discharged down to 20% ( the safe level for all types of modern deep cycle batteries ).

If you were to use the same amount of battery capacity with one of my systems, and say the cranking battery also has a 100Ah capacity, then the two batteries will only be discharged down to 60%.

Because all alternators in late model vehicles can easily charge two or more batteries at the same time, this means that when you do start your drive, you will need 1/3 less driving time to fully charge the two.

Plus each battery will not be charged with as high a current, which again, is kinder on the battery.

And if you need more capacity, you have the added bounce of having 130Ah available verses just 80Ah with the DC/DC or Standard VSR setup. And the additional battery capacity available at no extra cost and no extra weight or space lost.

Next, and Dave, this is one I disagree with you on. You can use dissimilar batteries in a parallel DBS setup and you will not have any problems that are different to problems you can have when using identical batteries.

Furthermore, my system can actually take advantage of different battery types and put that to use.

If you have a rapid charge battery like an Optima as your auxiliary battery, every time you turn off your motor, because the auxiliary battery is always going to be in a higher state of charge than the cranking battery, and because of the unique way my isolators work, the higher charged auxiliary battery is able to back discharge into the cranking battery.

This feature, over a short period of time after one of my systems is fitted to a vehicle, actually increases state of charge of the cranking battery. And this in itself has lots of benefits, like a healthier cranking battery, which makes it easier to start your motor and helps to increase the cranking battery's life span.

Babs, this is just the basics but as you can see, there is no other DBS that can match the benefits my systems offer. And this is not unsubstantiated sales hype, it's based on more than 25 years that my isolators have been in use.

[Jimmy93]

Battery wise, I have been looking at replacing my second battery and after talking to someone at batteryworld I am considering getting a Century Marine pro 100ah.

Basically he suggested that as my battery box vents to outside that an AGM is unnecessary, it will charge faster but at double the cost.

And they are a bargain at the moment, $183 at BCF.

[drivesafe]

Basically he suggested that as my battery box vents to outside that an AGM is unnecessary

Hi Jimmy, and I wouldn't be taking too much notice of someone who tells you that sort of dangerous crap.

AGMs vent gas and should only be fitted in a well vented are, just like wet cell batteries.

When a battery is being charged by an alternator, no matter what type is is, it is highly unlikely to gas.

The most common situation where batteries can be caused to gas, is when charging with a battery charger, or DC/DC device.

With this type of charging, many brands of AGMs batteries can actually start to gas at a lower voltage then wet cell batteries.

As for the type of battery you can fit in your battery box, well your expert should have already known the cranking battery is a wet cell anyway.

[Kumo keith]

I'm looking into dual battery-ing the truck (pretty keen on a Traxide unit now), and looking at the cranking battery it has a piece of small diameter tube that vents under the truck directly from the interior of the battery (vent port shown here)

https://www.aulro.com/afvb/images/imported/2015/12/770.jpg (http://s1356.photobucket.com/user/kumocycles/media/20151208_104915_zpszmsuq0og.jpg.html)

Does anyone know if any suitable aftermarket deep cycle batteries have a similar vent port?

[drivesafe]

Hi Keith, you may not need the vent tube, it depends on the mounting location of the battery.

Where are you planning on mounting your second battery?

[rovernutter]

Now I use a Narva voltage sensitive relay , cost $44. This works fine for and keeps things simple.
I have found this the best. Something simple and not much to worry about.

You are going to get voltage drop no matter how thick a cable you run. The longer the run, the more voltage drop. DC/DC chargers are good for were the auxiliary battery is some distance from the main battery. You really need them if your battery is in a camper or caravan. Of some benefit if the battery is in the rear of the car. Of little or no benefit if the battery is under the bonnet.

In 99.99% of cases a AGM will never expel any gases. They have a safety valve that will allow gas to escape only in the cases where the battery is about to explode. This would only be in the case of some major fault with the battery, which is a very rare occurrence.

Vehicle manufacturers only put in alternators that just cover the peak voltage load of the cars electrical system. The larger the alternator the more expensive it is and the more power required to drive it. The amount of amps available to charge the battery will depend on how much other power is being used at the time. If you are driving at night time with the headlights on high beam, the air-con going, and listening to your favourite tunes flat out, there is probably little power left to charge the battery. If on a nice day with the windows down and taking in the quiet serenity, there is probably quite a lot of power to spare to charge the battery.

[jackdef90]

The optima (deep cycle) I have doesn't , and the varta (cranking and accessories) which is same as original on a 2.4 tdci but with higher Cca and ah rating doesn't either.

[Kumo keith]

Hi Keith, you may not need the vent tube, it depends on the mounting location of the battery.

Where are you planning on mounting your second battery?

I was hoping to fit the aux battery in under the passenger seatbox next to the cranking battery if I can find the right option

[drivesafe]

Hi again Keith and any battery will be fine there.

If you were going to mount the battery in the cab, then it's best to mount it in a plastic battery box.

[rovernutter]

I'm looking into dual battery-ing the truck (pretty keen on a Traxide unit now), and looking at the cranking battery it has a piece of small diameter tube that vents under the truck directly from the interior of the battery (vent port shown here)

https://www.aulro.com/afvb/images/imported/2015/12/770.jpg (http://s1356.photobucket.com/user/kumocycles/media/20151208_104915_zpszmsuq0og.jpg.html)

Does anyone know if any suitable aftermarket deep cycle batteries have a similar vent port?
An AGM does not need one and is fine to mount there. It is only the flooded lead acid batteries, like your standard starting battery, that need the vents.

[drivesafe]

You are going to get voltage drop no matter how thick a cable you run. The longer the run, the more voltage drop. DC/DC chargers are good for were the auxiliary battery is some distance from the main battery. You really need them if your battery is in a camper or caravan.

Hi rovernutter and while there is always going to be a voltage drop in long runs of cable, particularly when it's to a caravan or camper trailer.

But if you run decent size cable, like 6B&S twin ( 13.5mm2 x 2 ) between the cranking battery and the house battery, if the house battery is low, the voltage drop is more likely to be greater at the battery when using a DC/DC device than it is when using decent cable.

And no that is not an error. Most people think that because a DC/DC manufacture states that their DC/DC device can charge at say 14.4v, that that is the voltage it will charge a low battery at.

The reality is that because these devices are current limited, they will actually be pulled down to a much lower voltage when trying to charge a low battery and will not get the battery terminal voltage to 14.4v until the battery reaches around 80% SoC.

Where as, because an alternator has a much, MUCH high current capacity, it will charge a low battery with both a higher voltage and higher current and the battery will reach the 80% mark much quick, which means the battery is always going to be in a better state of charge, when using an alternator.

Also rovernutter, I think you also need to check the current capacity of new alternators. They are a LOT higher than you think.

[rovernutter]

Hi rovernutter and while there is always going to be a voltage drop in long runs of cable, particularly when it's to a caravan or camper trailer.

But if you run decent size cable, like 6B&S twin ( 13.5mm2 x 2 ) between the cranking battery and the house battery, if the house battery is low, the voltage drop is more likely to be greater at the battery when using a DC/DC device than it is when using decent cable.
From comments posted, it appears that this subject gets debated on a regular basis. So I will try and keep this brief.

There is a formula that calculates voltage drop. Voltage drop equals the length of the cable in metres multiplied by the current draw in amps multiplied by copper resistance of 0.017. This is then all divided by the cross sectional area of the copper part of the cable in square millimetres.

What most people do not take into account is that the length is the total length, there and back, of the cable to the main battery.

From what I have found is that by the time you weave the cable around the engine bay, down to floor level, to the back of the car and then back up to the battery, you at looking at a bit less than 4 metres. So there and back is 8 metres in total.

As people were talking about a 40 amp charge rate. I will use this in the formula and the 6B&S cable diameter.

So the voltage drop will be (8x40x0.017)/13.5 or .4 volts.

If you were running it to a caravan, you can easily double the length of cable and the voltage drop would be (16x40x0.017)/13.5 or 0.8v.

I simply gave up on trying to run a cable big enough to my camper to charge the battery is any sort of reasonable time.

This is just from my experience. It will vary from vehicle to vehicle. It will depend on whether you have an old type alternator or the newer variable voltage ones. It depends on what voltage you are getting at the main battery, etc, etc.

The new style alternators only run at 14.4 volts for a short period of time after starting the car. They then drop back to around 13.5 volts. This makes charging aux batteries a pain. I think this is why DC/DC chargers are becoming more popular.

There are just too many variables to give a simple answer that will cover all vehicles. So I am not about to recommend any particular setup.

[drivesafe]

Hi again rovernutter and you, like most people, have fallen for the supposed voltage drop advantage DC/DC devices are claimed to resolve.

You just posted up some nice math but you only gave half the story.

I have carried out test on my own vehicles and on other, and with low batteries, usually two and sometimes three, there will be more than a 1.0 volt drop.

But these same tests have in excess of 60 amps being drawn by the low batteries and the high amperage is the reason for the large voltage drop.

If batteries are drawing 60 plus amps, the amount of voltage drop becomes irrelevant.

As for how alternators work in deferent vehicles. Here is a testimonial from one of my customers, and it covers the three main types of alternator operations found in Land Rovers, plus what happens when you use a DC/DC device in similar circumstances.



This is an E-mail I received late last year and demonstrates the need to get RELIABLE info for equipping a vehicle with a DBS that actually works and not rely on what so called experts in this field claim.

These guys fitted their own DBS and had no problems yet the fifth guy got his DBS "professionally" installed, and look at the results.

Note, the D2 has a constant voltage alternator, the D3 has a variable operating voltages, and the D4s have Regenerative Braking Voltage operation.

This covers just about every type of alternator operation.

--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

Hi Tim

Sorry for the long email ? in the second half of the email my mate with a 200 series wants to know if you can help him

It seems like only yesterday that we installed your dual battery kits in 4 vehicles (D3, 2 x D4, D2) ready for a big trip. We've been back a while so I just wanted to give you an update on how the battery kits went.

In short, they were brilliant. We installed all 4 kits you sent us in one day. Aside from the fiddly process of removing trim pieces and working in the tight confines of a Land Rover engine bay the installation was straightforward with your instructions.#
Throughout the trip the kits never missed a beat, and others on the trip had lots of electrical issues.

On a few occasions the battery guard did it's job cutting out the fridges, but this was usually when we were camped in one spot for a few day (very little or no driving) in very hot weather (making the fridges run almost non-stop). It took surprisingly little driving to provide a good bulk charge back into the batteries.

We travelled the Tanami Track, Gibb River Rd, Kalumburu Rd, Mitchell Falls NP Road and the Great Central Road and nothing rattled loose or played up in any way.

Our friends in a 200 series Land Cruiser, on the other hand, did not fare so well when it came to electrics. Following local advice he had a Ctek DC-DC charger installed professionally by a very large and well known auto electrician here in Newcastle. They also installed an auxiliary circuit for his fridges and accessories etc connected to the aux battery.

In short the system never worked properly. Initially the DC-DC was installed in a very hot part of the engine bay making it cut out once the engine warmed up. We repositioned it behind his grill but even then he only got a useful charge on big driving days. On days were we did short trips around camp he was always having problems with a flat aux battery (including the extra aux battery on the trailer). To further add to his woes the auto elec did NOT install any form of low voltage protection on the circuit for his fridges and accessories. He ran his batteries far too low a few times and it didn't take long for the aux in the engine bay and the aux on the trailer to both die completely.

He couldn't believe how well our systems worked. So he was wanting to find out a little more:

Feel free to use my feedback as a testimonial if you wish.

Thanks


NOTE, the Toyota now has one of my systems installed and all is working properly.

[rovernutter]

Tim, I have never used your products and therefore cannot comment on them. I am in no way commenting on your products or knowledge.

I can only comment from my own experience. It is not from information from people trying to sell their products.

The thing that killed me most was the ECU controlled alternator. With the relatively low voltage they switched to, combined with the voltage drop to the camper, there was no way that the camper battery was going to charge in any reasonable timeframe. I doubled the size of the cable and it made bugger all difference. That is when I started to do the calculations to work out what size cable I would need. Just was not practical.

DC/DC charger works well and will charge the battery during a normal travel day, with the fridge running.

Obviously you have had different experiences, I can only comment on mine.

In regard to your email from your customer, it should be noted that the Toyota had a voltage variable alternator, I do not believe that the Discos do. Therefore, the DC/DC charger would offer no benefit to the discos. The issues they appeared to have was with the unit failing to work rather than the concept of the DC/DC charging system. Maybe the unit didn't like the heat, that it was installed badly, or it was a rubbish brand. I do not know why it didn't want to operate, so can't comment.

[drivesafe]

Yep correct, Toyotas have a basic variable voltage system, and this one had an Alternator Voltage Booster Fuse installed when my kit was installed.

Also, Land Rovers not only have variable voltage operating alternators, they will operate even lower than any Toyota does.

This does not alter the fact that you still do not a DC/DC device in these vehicles and with more than 4,000 D3, D4, RRS and quite a few L322 RR plus a very large number of Defenders equipped with my gear, and no one has the problems you are having.

[rovernutter]

Yep correct, Toyotas have a basic variable voltage system, and this one had an Alternator Voltage Booster Fuse installed when my kit was installed.

Also, Land Rovers not only have variable voltage operating alternators, they will operate even lower than any Toyota does.

This does not alter the fact that you still do not a DC/DC device in these vehicles and with more than 4,000 D3, D4, RRS and quite a few L322 RR plus a very large number of Defenders equipped with my gear, and no one has the problems you are having.
I suppose I should be more specific.

The Toyota Land Cruiser had a Temperature Compensating Alternator. It just works off the engine temp. While the motor is warming up it puts out full voltage. Once it is at running temp it cuts back on the voltage. It is not that smart, like the one on my car. So while it is at running temp it only puts out the lower voltage and therefore takes considerably more time to charge the battery. Such systems can benefit from a DC/DC charger.

The LR3/LR4/RRS have a Regulated Voltage Control (RVC) alternator. It is a lot more sophisticated and monitors the load on the system, voltage, and a number of other factors. It will therefore take into account the extra draw of the auxiliary battery when working out its output voltage. Therefore this system should charge both batteries quicker than the old style alternators and should not need a DC/DC charger for batteries, particularly those under the bonnet.

I am also aware that people make units to trick the temperature type alternators to put out a higher voltage when the motor is warm. I did not use one of these as I was unsure of any damage that adding the extra voltage to the higher cold voltage would do. It also runs the higher voltage when the batteries are fully charged. I only need the extra voltage a few weeks of the year when the camper is on the back of the car.

But it is all about horses for courses. What suits me will not suit many others. I do not believe that there is a one size fits all solution.

But I do not wish to turn this into another debate about batteries, so I will leave it at that.

[Babs]

Well that was a very interesting read, thanks Boyz.

Don't worry too much about it being a debate, I think it's really good you both listed all the Pro's & Con's

Sent from my iPhone using Forum Runner

[Blknight.aus]

Hi Dave and thanks for all that info, and while I agree with most of it, the difference between what you get in the way of available accessories battery capacity is quite a large amount more than you covered.



Next, and Dave, this is one I disagree with you on. You can use dissimilar batteries in a parallel DBS setup and you will not have any problems that are different to problems you can have when using identical batteries.



for the first snippit...

Agreed, but I didnt really need to see the point in delving any further into it than just the simplest benefit in the simplest perfect world environment assuming that the DCDC allowed the batteries to remain connected down to the 50% threshold on the main battery (most dont), its still going to burn amps shunting the power across. when I sat down and did the numbers across an amps meter the calculated amps that most DC/DC chargers burn up in a 24 hour period is enough to run my engle for 3 hours. by comparison the milliamps an SC80 burns in the same 24 hours might run a a pair of my pole marker leds for a couple of hours.

I've just gone back and re-read the post. I made an absolute lunch out of writing out what I was trying to put across... I left out the bit about "assuming the DCDC remained connected for the same length of time as the traxide"... I'll go back and edit it in in blue, on an edit no I wont, I made the post 2 days ago so its locked


for the second snippit

as for the battery thing. I wont deny that you can do it without problems but there are minor benefits that can be had if you stay on the same tech type for the batteries and there are some drawbacks if you regularly push the limits of friendship on the batteries of course theres some majorly huge pitfalls to fall into if you go wildly dense about crossing technology platforms in batteries without taking into account the variation in the optimal charging and discharging requirements. Call it me being lazy, easier to advise that the best results can be had if you stay on one platform.

[DiscoMick]

People who know much more than me have already posted, so I'll just support some things from my experience.
Starting batteries are designed for quick bursts of power, which is what you need when winching, whereas second batteries such as deep cycle and AGMs are designed for slow draw down for a fridge and similar demand.
Connect the winch to the starting battery, which will be a wet cell, because it will provide large bursts of charge in a short time. Keep the engine running while winching and you won't have a problem.
Install an AGM second battery (mine are 120 in the vehicle and 100 in the camper) for a slow drawdown to run your fridge.
You probably don't need a DC-DC charger in the vehicle. After all, an alternator should make at least 80 amps, and then its a matter of how much your wiring is rated to send power from the first to second battery. Mine has 60 amp fuses. Most DC-DCs only power to 20-30amps, so its only a gain if there is a lot of current loss. For example, I did install one in the camper, simply to boost the power running all the way down from the front of the vehicle through the trailer plug and into the camper.
If you want to go Redarc they have a simple dual battery isolator for about $150 from memory. We had one in the Disco, which died in the desert, and bought another one in Alice. Cheap, simple and does the job.
If you want something better, the Traxide seems to be unusual in that it allows the fridge to draw on both the second battery and part of the starting battery, but ensures it still has enough to start the vehicle, so that gives more available battery reserve and so more running time.
We have a Traxide in the Defender and its great. Our first and second batteries are connected with dual 60 amp fuses, which seems to work fine, but I know Drivesafe says you can go higher if its is done correctly.
As for solar, most solar kits come with a regulator, so you don't also need a solar DC-DC to charge off solar, as the regulator does the job. Just fit Anderson plugs and charge the battery directly.
Carry a 240 volt multi-stage charger if travelling and, when mains power is available, hook it up and give your system an overnight boost, which should see it become fully charged (about 12.9 volts).
I hope that helps and I have got it right. Seems to work for me.

Sent from my GT-P5210 using AULRO mobile app

[inside]

Just to post my thoughts on this as I went through it some time ago and did a bit of research and why I went Narva VSR.

Pros of Narva:
Small - In a defender you can fit 2 optimas and one N70 plus Narva VSR in the battery box
Water resistant - IP65 (defender drivers need to worry about this)
Narva brand name - they make quality gear
Cheap - $42 on eBay. The $150 you save will get you at least half a 120AH deep cycle battery. Or you could go from 120AH to 260AH. $150 is also a 120W solar panel.

Anyway Narva VSR for me, simple and cost effective.

[drivesafe]

Hi inside, you have missed one of Babs requirements. He wants to set up for winching.

All these basic isolators do not have that ability and while there are a few that can have a switch added to allow them to link batteries for jump starting, they have a major potential drawback, when doing so.

Some isolators do have the ability to link batteries using a switch, but in most cases, this is only to allow the batteries to be linked for jump starts, not for winching, because the isolators are not designed to carry high currents for more than a few seconds.

For this reason, the instructions that come with these types of isolators usually specify the use of a PUSH BUTTON type switch, and this is not much use when you want to link batteries for winching.

Of the isolators that are able to carry the higher currents required when winching, they use a standard toggle switch to link the batteries, but this then adds another problem.

These types of isolators use the switch to bypass the VSRs electronics and just turn the solenoid on. Great while winching or for jump starting, but if you forget to turn the switch off after you have finished, you now have the potential to flatten both your auxiliary battery and your cranking battery, when you turn your motor off.

With my USI-160, if the motor is off and you select Jump Start, the switch does not bypass the electronics and just turn the relays on.

With the USI-160, the switch tells the microprocessor that you want to jump start, and the microprocessor then turns the relays on, and if the motor starts, the isolator stays on. But if the motor does not start in 20 seconds, no matter whether the switch is still in the ON position, the microprocessor turns the isolator off.

If the motor is running ( and the isolator will already be on ), and you want to link batteries while winching. When you set the switch to WINCH mode, the microprocessor, sensing that the motor is running, keeps the isolator on but resets the CUT-OUT level from 12.0v to 10.0v so that the isolator does not turn off while you are drawing high currents and dragging the batteries lower than they normally would be operating at, that is unless the batteries are being dragged too low, then the USI-160 protects the auxiliary battery.

If after you finish winching and you forget to switch the isolator out of WINCH mode, 5 minutes after you turn your motor off, the microprocessor automatically resets the CUT-OUT level from 10.0v back up to 12.0v. So you will not risk ending up with two flat batteries.

Also, the USI-160, when in SHARED mode, allows for additional capacity from the cranking battery to be used to run accessories while you are parked, and if you have solar or connect a battery charger to the auxiliary/house batteries, the USI-160 allows reverse charging of the cranking battery.

All these features are not available with the cheap standard VSRs, so as the saying goes, you get what you pay for!

[numpty]

Just my twopence worth. ;)

I have just fitted a large switch (marine type) connecting my two starter batteries. It has provision for OFF, BATT 1, BATT 2 and BOTH. Switch is mounted on the front of the Seat box (passenger side) and it's a simple matter of switching it over regularly eg after refuelling. About $50.

Same system I had in my Stage 1 for 20 years and the same in my 110 for the past 9 years. It works for me and I have never had a problem with it. Everything works off the battery which is selected.

When using the winch, switch to BOTH.

I know Tim is not a fan, but it works.:)

[inside]

Tim, well maybe not a case of get what you pay for but if you pay more you get more features. It's not like a Narva VSR is cheap and nasty, it is very simple in operation so therefore cheaper.

People will have varying requirements, for me I winch with a PTO and I jump with jumper cables.

Different products for different requirements.

[Toxic_Avenger]

I'm trying to get my head around the science (and scientific responses) of how one can reasonably expect to choose a dual battery controller for use when winching. I think I got my selection right in my setup (albeit probably overkill), but my question aims to answer 'what's the minimum I can get away with'.

So I have some questions that I might pose to the masses.

1) My understanding is that if 2 batteries are combined, for say, a winching operation, then 2 x 12V batteries with a load of say 400A, will draw 200A from each battery, when they are connected in parallell. If 1 battery is connected, then this battery is required to supply the entire 400A. Is this statement correct?

2) What sort of current draw could one expect from an average winch at a average pull weight, on a reasonable number of winch rope layers? I'm led to believe a ball park figure for 9500lb at first layer could be 350A... and higher when we start talking about 4th layer on the drum, larger HP winch motors, and larger weights to move. Is this correct in other's opinion? (Has anyone put an amp meter on a winch under free-spool conditions?)

[Blknight.aus]

I'm trying to get my head around the science (and scientific responses) of how one can reasonably expect to choose a dual battery controller for use when winching. I think I got my selection right in my setup (albeit probably overkill), but my question aims to answer 'what's the minimum I can get away with'.

So I have some questions that I might pose to the masses.

1) My understanding is that if 2 batteries are combined, for say, a winching operation, then 2 x 12V batteries with a load of say 400A, will draw 200A from each battery, when they are connected in parallell. If 1 battery is connected, then this battery is required to supply the entire 400A. Is this statement correct?

2) What sort of current draw could one expect from an average winch at a average pull weight, on a reasonable number of winch rope layers? I'm led to believe a ball park figure for 9500lb at first layer could be 350A... and higher when we start talking about 4th layer on the drum, larger HP winch motors, and larger weights to move. Is this correct in other's opinion? (Has anyone put an amp meter on a winch under free-spool conditions?)

your assumptions are on the money at the level that you're needing to be worried about

point 1 is on the money
point 2 is also close enough. my aldi draws 50 amps on no load startup (my clamp meter doesnt register fast enough to capture the split second startup current, this is the number that the max hold setting captures) and settles at about 30 amps when winching in with just enough tension on the cable to make it sit nicely.

IF you want the cheapest and nastiest automatic dual battery system you can get go buy a 200A relay and wire its input to a circuit feed that comes on off of the VSR (voltage sensing relay) thats in the vehicle (controls power to things like electric window heaters and seat heaters) or off of the ignition. On the VSR The aux battery will only get connected once the main battery voltage is over ~13.2v and will disconnect at about the same point. Should cost you around $30 to build it all up including the cabling.

the winching thing. This is another one of those things that the traxide does that a DCDC cant. DCDC units are one way so the amps that are in the aux battery are not available to the main to share off of the winch.

IF you're going to winch (or use large inverters) through your DBS you are essentially cutting out the ability to use most stock Deep cycle batteries as the aux as while you may not draw all of the AH while you winch you're pulling them out faster than the battery is designed to deliver them. (sciencey blurb here about amps volts plate construction heat peukets law omitted) which shortens the life of a deep cycle battery if not killing it completely.

If you want to go utterly ghetto on your DBS.. just get yourself a battery isolator switch, fit it up and wire the 2 batteries in parallel through it. just remember that you have to turn it off manually or in 3 days you'll be up agaisnt 2 flat batteries.

[jc109]

A couple of comments here have said that using the Traxide unit you can charge all batteries via a cable to one of the auxiliaries. And I see the same on the Def-USI-FPC diagram linked to earlier.

I had thought that optimal charging for all batteries would be achieved by charging via the cranker first. Have I got it wrong? I hope I do, as it would allow a rewiring to a far simpler and more flexible set-up.

[Toxic_Avenger]

So how would a $30 200A relay job handle winching? I'd think a lifespan of minutes if batteries are not combined, marginally longer if joined.

How would a traxide unit handle 350A if the batteries are not put into 'winch mode'? Wouldn't a large load from a big winch under sub-optimal conditions put even the most esteemed product dangerously close to it's current handling limit of 160A continuous, or make/surge current lilmit of 240A (usually this terminology is referred to as current rating for ~10seconds) ?

I know everything has a lifespan under extreme use, but the trend I have seen in my research is that 160A/240A is pretty much the biggest rating you'll get on an automotive battery controller, hence why I went for a marine grade one. On paper the Blue sea ACR I have kicks ass at 2000A cranking current (10s) or 225A continuous (24/7).
I'm looking for reasons to assure myself that I didn't spend 2x more on that unit than I needed to :wallbash:

[drivesafe]

A couple of comments here have said that using the Traxide unit you can charge all batteries via a cable to one of the auxiliaries. And I see the same on the Def-USI-FPC diagram linked to earlier.

I had thought that optimal charging for all batteries would be achieved by charging via the cranker first. Have I got it wrong? I hope I do, as it would allow a rewiring to a far simpler and more flexible set-up.

Hi jc, once batteries are in a parallel setup, all batteries will be charged at the same rate, if charged by a battery charger, solar or by a DC/DC device.

All these devices are constant CURRENT charging devices

If being charged by an alternator, which is a constant VOLTAGE device, each battery will be charged at that battery's optimum charge rate, regardless of the type and state of charge of any other battery in the same circuit.

[drivesafe]

Hi Mitch, when I was developing the USI-160, I initially was going to produce a 240 amp isolator, but after quite a considerable amount of researching and testing, I found that the 160 amp version is more than adequate and to date I have never had one returned because the relays were burnout.

When you link an auxiliary battery to a cranking battery, for winching, the maximum continuos current draw from the auxiliary battery is less than 150 amps.

The actual total current draw of most winches is usually no more than 300 amps, unless the winch is forced into an overload ( stall ) situation.

My isolators will tolerate 400 amps for a very short time.

At 300 amps, the average alternator will usually provide around at least 50+ amps and the remaining 250 amps is provided by the two batteries. That means "roughly" 125 amps per battery.

Battery type and size, plus cable thickness and length, will determine how much current is drawn from each battery while winching.

[Blknight.aus]

A couple of comments here have said that using the Traxide unit you can charge all batteries via a cable to one of the auxiliaries. And I see the same on the Def-USI-FPC diagram linked to earlier.

I had thought that optimal charging for all batteries would be achieved by charging via the cranker first. Have I got it wrong? I hope I do, as it would allow a rewiring to a far simpler and more flexible set-up.

relay based systems that work on overall voltage on all the batteries for disconnect/connect by means of a relay you are correct, so long as the batteries are all connected you can charge from wherever you like. For things that automatically isolate or are one way only then its a different kettle of fish and your generally better off connecting to the aux battery as it will be the one that will be at the lower state of charge most of the time.


So how would a $30 200A relay job handle winching? I'd think a lifespan of minutes if batteries are not combined, marginally longer if joined.

How would a traxide unit handle 350A if the batteries are not put into 'winch mode'? Wouldn't a large load from a big winch under sub-optimal conditions put even the most esteemed product dangerously close to it's current handling limit of 160A continuous, or make/surge current lilmit of 240A (usually this terminology is referred to as current rating for ~10seconds) ?

I know everything has a lifespan under extreme use, but the trend I have seen in my research is that 160A/240A is pretty much the biggest rating you'll get on an automotive battery controller, hence why I went for a marine grade one. On paper the Blue sea ACR I have kicks ass at 2000A cranking current (10s) or 225A continuous (24/7).
I'm looking for reasons to assure myself that I didn't spend 2x more on that unit than I needed to :wallbash:

the traxide wouldnt be handling 350A it would be handling 175, actually less as the alternator would be kicking out its absolute limit so if you had a 100A alternator then youd realistically be taking 270 from the battery (assuming that 80A was available from the alternator) so now the traxides or the 200A relay is only dealing wit 135A.

at the end of the day the traxide is a relay based system putting one into its various modes just changes the voltages and timings at which it will drop out the relays.

when you take the vehicle fording or dunk it at the beach at least the ACR will stand up to that better than anything else thats been discussed here.

[Toxic_Avenger]

Gentlemen, the input has been very insightful.
I didn't consider that the alternator also adds to the power delivery equation, seems a very elementary mistake on my behalf. But I'm thinking how the setup is wired together influences how much current the ACR or equivalent is required to handle.

In my instance, I wired the winch to the AUX battery side of the ACR, so am I right in thinking that in this instance the alternator output + battery output still has to be carried through the ACR?

[drivesafe]

Hi again Mitch.

A winch's positive ( + ) cable should always be connected to the cranking battery, not the auxiliary battery.

There is a very good reason for this in that the cable distance from the alternator to the winch needs to be kept as short as possible, to gain the highest voltage possible at the winch while winching.

By connecting to the auxiliary battery, you not only increase the cable distance, which can demonically increase voltage drop because of the long cable.

But the setup, like yours, then needs to go though some form of switching/isolating device, and this just adds more voltage drop to the circuit.

[jc109]

Hi jc, once batteries are in a parallel setup, all batteries will be charged at the same rate, if charged by a battery charger, solar or by a DC/DC device.

All these devices are constant CURRENT charging devices

If being charged by an alternator, which is a constant VOLTAGE device, each battery will be charged at that battery's optimum charge rate, regardless of the type and state of charge of any other battery in the same circuit.

I've got an SC80 installed and for some reason I thought that the trickle charge running through the starter first would keep it in better nick than having the current come the other way via the aux and the DBS. I assume what you've said above is correct provided the starter's voltage is high enough to keep the DBS open to the aux. If it's low, as mine often is when I come home from FIFO, then how does the charge make it to the starter?


relay based systems that work on overall voltage on all the batteries for disconnect/connect by means of a relay you are correct, so long as the batteries are all connected you can charge from wherever you like. For things that automatically isolate or are one way only then its a different kettle of fish and your generally better off connecting to the aux battery as it will be the one that will be at the lower state of charge most of the time.

In my case it's usually the cranker that's lower. It always loses its charge very quickly if I forget to put the charger on before I fly north. Actually, I think it's on its way out but I've not been able to prove it. I do disconnect the relay when I go away, but it doesn't seem to make a difference these days.

[Blknight.aus]

In my instance, I wired the winch to the AUX battery side of the ACR, so am I right in thinking that in this instance the alternator output + battery output still has to be carried through the ACR?

correct.

3 sources of amps for the winch the allternator, the main battery and the aux battery.

your setup goes Alternator--main batt---ACR---winch---AUX battery all amps flow towards the winch

you should be looking at
Alternator-winch-main battery-ACR-aux battery

in reality you wind up with the alternator, main battery, the winch and the ACR all hooked up to the one "point"

Another thing worth noting, if you have a deep cycle battery and a cranking battery and you start putting huge load on the cranking battery is going to do more work initially than the deep cycle battery so if you have your winch hooked up to a deep cycle battery and the Main battery is trying to feed it through the ACR it may well be the case that the ACR is doing even more work than the simple maths makes it look like..

[Toxic_Avenger]

Hi again Mitch.

A winch's positive ( + ) cable should always be connected to the cranking battery, not the auxiliary battery.

There is a very good reason for this in that the cable distance from the alternator to the winch needs to be kept as short as possible, to gain the highest voltage possible at the winch while winching.

By connecting to the auxiliary battery, you not only increase the cable distance, which can demonically increase voltage drop because of the long cable.

But the setup, like yours, then needs to go though some form of switching/isolating device, and this just adds more voltage drop to the circuit.

So other than the battery type (cranking vs deep cycle or hybrid style- I have 2x optima blue tops), what I'm reading is that attaching to the cranking battery is to 'gain the highest voltage possible' at the winch motor. This is synonymous with voltage drop, right?).

I have run 70mm2 cable from the solenoid box to the battery, and 50mm2 from the solenoid forward to the winch motor. This is 2x the conductor area that was supplied with the standard cable.

Warn recommends <1V voltage drop, which IIRC, I shot for 0.3V drop based on cable run lengths, conductor CSA, expected cable / ambient temps etc. I reason that an extra 40cm of cable from the main battery thru the ACR and battery switch will not be a significant concern given the overall conductor length in the system.

I could have attached directly to the battery (either starting battery or aux battery), but this raised concerns with potential cable damage under the vehicle, which I wish to mitigate wherever possible.


correct.

3 sources of amps for the winch the allternator, the main battery and the aux battery.

your setup goes Alternator--main batt---ACR---winch---AUX battery all amps flow towards the winch

you should be looking at
Alternator-winch-main battery-ACR-aux battery

in reality you wind up with the alternator, main battery, the winch and the ACR all hooked up to the one "point"



I understand the differences between setups, but other than voltage drop (which I believe I've mitigated), what's the difference? Is it the limitations of the electrochemical reaction within the lead acid battery - ie make the connection to the winch one which is copper, not phase changing (for want of a better word) thru the battery electrolyte?

[DiscoMick]

As I understand it, starting batteries are designed to deliver a big burst of power in a short time, which is what a winch needs, whereas deep cycle batteries are designed for slow draw down and recharging, such as for a fridge. Therefore, the winch should draw on the starting battery. Is that correct?

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[Toxic_Avenger]

As I understand it, starting batteries are designed to deliver a big burst of power in a short time, which is what a winch needs, whereas deep cycle batteries are designed for slow draw down and recharging, such as for a fridge. Therefore, the winch should draw on the starting battery. Is that correct?

Sent from my GT-P5210 using AULRO mobile app

Correct, it the lead plate design which skews the battery towards rapid ability to carry current vs slow and low discharge. I'm running a hybrid style that is neither cranking nor deep cycle. But 750CCA and 55Ah rated... so best of both worlds.

I was led to believe that a winch needs a higher CCA rating... 200CCA wont do it... but if both batteries are the same, and within the CCA rating recommended by the winch manufacturer, and the voltage drop is within spec, then I still can't see where the problem is

[Blknight.aus]

the voltage drop that occurs is a natural P=V*A thing, as the volts go down the amps go up and as that happens all your nice "clacluated at 13.8V"numbers go out the window. Then things get hot and the "calcualted at 25 deg C" part of the numbers go out the window.

the wire on the alternator is the source of all your power ideally you want to keep the path from the alternator to the winch as short as feasible BUT you cant just hook the winch to the back of the alternator because the wire will not deal with 320amps coming back from the batteries to deliver the 400amps the winch wants when your alternator is pushing its 80amps worth to the winch.

And NO, you cant just fit a fat ass wire to the alternator, in some vehicles the wire size forms part of your current limiting and sensing.

Where you make the connection between the battery and the ARC for the winch, is in effect more or less irrelevant (assuming all cable is the same rating) its the side of the ARC that counts. Given your batteries are the same then the only thing that counts for you is where the alternator connects to the system while winching on one side the amps from the alternator will funnel down to the winch without having gone through the arc and on the other side the arc gets to carry the current. IF you're pushing limits that might be the difference between the ARC contacts getting hot and deforming or staying within operating tolerance.

Onto the Deep cycle VS cranking battery for winching thing. For this I'm just going to pretend that there is NO DBS and the batteries are just in parallel with the kind of cable that even I would hint at being probable overkill.

Oh, WARNING... sciencey blurby bit missing from post 45 of this thread approaching, I'll skirt it as best I can and try to avoid peuket and charging and surface effect and and and and I'll try to keep it as close to laymans while avoiding as many techy terms like thingy and insideoutsidemelty as I can. warning done with.


you're close, its not the electrochemical reaction, its the construction of the battery. Briefly yes, the electrochemical reaction does play a part but its Very minor, infact in almost but not quite all normal cases its so negligible its not even worth considering you're more likely to have more difference being caused by something else such as a pifling of an ohms worth of resistance from a bad batch of copper in a relay contact and you'll have an even bigger difference made just because no 2 batteries are ever physically or electrically identical. Thats the bit where me and drivesafe differ on the elctrochemical side of batteries, he works everything so you never have to be in the area that I'm usually getting roped into, the ragged ends of things being used to and beyond limit. where the unusual is normal and when a 1Ah difference in capacity is a big deal because your not looking at 1 out of 200 your down into the 1 out of 20 end of business. Also if you're worried about the electrochemical side unless you're being obfuscatingly difficult and trying to work out how to do it with obscure combinations like LiPO and NiCad when it comes to winching, stop. the realistic piffling of difference it does make is maybe almost not quite enough to power up the transmitter in the winch remote control.

Back to the physical stuff.

its plate surface size and acid quantity that make the difference a battery is only so big and you can either put a lot of plate surface area or a lot of acid into it.

IF you have a lot of surface area and a little bit of acid you get a lot of reaction but not for long
if you have a little bit of surface area and a lot of acid you dont get much reaction but you get it for a long time.
The voltage of the reaction is effectively the same regardless of if you have 400 molecules doing it or 400000000000000

when you dump the mass load onto your deep/crank combo the crank battery picks up the lions share of the load, that's what its designed for, the deep cycle battery does what it can and the acid start to turn back to water in both batteries. The crank battery chucks out all the magic in the acid really quickly because A, there's not as much acid to start with and B, there's more surface area for the magic to escape from.

ok So now the crank batteries running out of acid to make amps from. the deep cycle battery isn't so it starts to sacrifice itself because as the volts go down if the acid is still strong enough the reaction wants to continue so in order to produce the energy to maintain the volts the reaction happens faster, this creates heat and also damages the plates, in extreme cases it will cause the plates to buckle and can blow the internal links between the cells.

Clever people, who want to be able to winch and use a DBS that links a deep cycle to crank battery put a current limiting device between the DBS and the deep cycle battery. A short section of well protected but ventilated undersized wire will do nicely as will a handfull of other things.
I tend to use high wattage bulbs if I have to field bodge it.

Aint spark chuckin stuff fun...

[rovernutter]

Just a final note. Optima batteries are not the only choice for an AGM deep cycle battery. They actually have relatively low storage capacity for a deep cycle battery. There are a number of AGMs that have 100AH capacity or more out there and are often cheaper. So have a look around.

For example, this one has just as much storage as the most expensive Optima and is half the price http://www.ebay.com.au/itm/EXIDE-Leisure-Cycle-LCS24-86-Battery-/121716825504?hash=item1c56e35da0:g:aSEAAOSwI-BWQb2E

This one has 110ah and over 800CCA for just over $200 http://www.ebay.com.au/itm/EXIDE-Leisure-Cycle-LCS31-110-Battery-/121716825506?hash=item1c56e35da2:g:-1QAAOSwo0JWQb2F

[DiscoMick]

Thanks for the explanations.
I bought a Kickass 120 amp from Australian Direct for a good price, after seeing Nugget use one.
My winch is connected to the original LR starting battery, which is a big sucker and still going strong after 6 years.
So far its all good.

Sent from my SM-G900I using AULRO mobile app

[rovernutter]

I think that people are getting too tied up in how to wire up a winch.

Most people have a winch as an emergency device if they get stuck one day. It is not something they use on a regular basis, if at all.

So how you wire it up is not going to make a huge amount of difference for that couple of times you use it. The different wiring may mean that it takes a little longer to winch out. But what is 5 minutes over the life of the vehicle.

But if you want to get serious about the wiring, these are a few points you may want to consider.
1) Your main source of power is going to be the batteries, not the alternator. So wiring it to the batteries is better than the alternator due to voltage drop across the cables.
2) Voltage will determine how quickly the which turns. The higher the voltage, the quicker you will winch.
3) Batteries cannot produce high amps while maintaining voltage. Just check the voltage at your battery while you are trying to start the car. Typically it will drop to around 8 volts.
4) The less amps you draw from each battery, the higher the voltage and the quicker the winch will turn.
5) So if you can split the amp draw across 2 batteries, you will get a higher voltage to the winch.
6) The AH rating on a battery is typically calculated at what constant amps can be drawn from the battery over a 10 or 20 hr period. So if a battery can supply 5 amps for 20 hours, the manufacturer will typically quote it as being a 100ah battery.
7) The higher the amps you draw from a battery, the less total amps that batter can provide. If regard to Kickarse batteries, their 120AH battery can only supply 264 amps for 10 minutes, or a total of 44 amps. Reduce the draw to 73 amps, it can supply it for 1 hour, or a total of 73 amps. So by splitting your amp draw across two batteries, you will increase the amount of amps available for winching. This could easily be 3 times the winch time for doubling the number of batteries providing the power.

So I would wire the winch to the middle battery. That is, the one connected to the alternator and the one that the second battery is connected to.

Having two batteries running the winch will increase the speed of the winch through increased voltage and will significantly increase the winching time you will have.

The other thing to consider is how much power the alternator is actually providing anyhow. Those that have to winch will tell you that it is usually a wet miserable day when the tracks are slippery. So you are probably covered in mud and cold. So you will have the heater going flat out trying to dry out and stay warm. You probably have tried getting up the hill every way you can before winching, so the motor will be hot by now and the thermo fans are running on and off. It is usually the 5.00pm track that you get caught on, so it is now getting late and you have your lights on to see what you are doing. So how much power is left in the alternator to provide to the winch. The more amps the alternator has to put out, the lower the voltage it will provide to the battery or anywhere else due to the resistance in the cables. The higher the amps the less voltage gets through.

But all this does not mean much if you only winch for a short period once in a blue moon. I just would never wire it to the alternator as it is the lowest source of power when winching.

[dennisS1]

Why on earth would any one even consider wiring a winch to the alternator?
That is just silly on so many counts.
On a Defender getting back to the main battery isn't that easy, just wire it off the starter motor feed, the other big current drawer, have used this ever since I have had a winch no problem.
As already stated it's usually a short term run, I don't even start the car to pull-out Toyotas.

Dennis

[rovernutter]

On a Defender getting back to the main battery isn't that easy, just wire it off the starter motor feed, the other big current drawer, have used this ever since I have had a winch no problem.

But where have you put the earth?

People forget that the earth is just as important as the positive lead. Often the earth leads from the battery to the chassis and then the chassis to the motor are not brilliant and would hamper the winch if earthed out to either of these.

[inside]

Just a final note. Optima batteries are not the only choice for an AGM deep cycle battery. They actually have relatively low storage capacity for a deep cycle battery.
Good thing about the Optima is their short height of 199mm. A taller battery wouldn't fit in the Defender seat box for me as mine gets shorter towards the rear. Other Defenders might be different.

[DiscoMick]

Why on earth would any one even consider wiring a winch to the alternator?
That is just silly on so many counts.
On a Defender getting back to the main battery isn't that easy, just wire it off the starter motor feed, the other big current drawer, have used this ever since I have had a winch no problem.
As already stated it's usually a short term run, I don't even start the car to pull-out Toyotas.

Dennis

The alternator is already wired back to the starting battery, so just follow that route.
Also, I think it was pointed out earlier that alternators are not normally wired for the high current draw generated by a winch, which could have unpleasant results.
Is a starter motor wired to cope with the draw from a winch?

Sent from my GT-P5210 using AULRO mobile app

[drivesafe]

The reason for connecting the winches positive ( + ) cable to the cranking battery is that it is usually the centre point in a two battery setup, where the alternator and auxiliary battery meet at the cranking battery.

But far more importantly, in either a one or two battery winch setups, using the cranking battery is also a way of filtering current surges and voltage spikes.

As for voltage levels while winching.

You should not draw the batteries down below 10v while winching as this will be approaching the stall voltage range at the winches.

Regularly taking a winch motor down to a stall situation, while the alternator is unaffected, it is not good for the winch motor or the batteries.

If you use best practice while winching, you will use a winch in the manor Dave has already pointed out. This winch and rest cycle is going to demonically reduce the chances of a stall situation occurring in the first place, because this type of winch use helps to keep the operating voltage levels as high as possible.

[87County]

Very informative discussion - my thanks to the contributors. This post is to help me keep an eye on it :).