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Mick-Kelly
6th June 2004, 11:25 PM
G'day all
Ive just been poking round in te engine bay again and now have some quetions regarding my dual battery system. From what i can tell ive got two regular (cranking type) batteries with all the relevant solenoids etc. the wiring from the second battery runs along the chasis to the rear where it terminates in a fitted plug, presumably for a fridge.
My understanding is that most dual batteyr setups run a standard and a deep cycle and have a monitoring system of some kind. My system was installed by the PO so im not to sure what his goals were. Is there anything there in the way of a monitoring system I just havent foundyet and will it create problems if I run a deep cycle as the second battery.
cheers
Mick

drivesafe
7th June 2004, 04:16 PM
First off, you can use a cranking type battery or a deep cycle type battery as your second ( auxiliary ) battery.
The use of a solenoid, by itself, to connect the auxiliary battery to the charge system is a BIG mistake.
The problem is that solenoids can pick up from a supply voltage as low as 8 volts so if your main battery is on it’s way out or worse has already lost a cell or two, the solenoid will still operate and you actually start the vehicle using the power from the auxiliary battery and you will have no idea that the main battery is in need of replacing.
Not only are you now starting using power from the auxiliary battery but until you are running the motor with some revs, the alternator will not be putting out enough amps to charge the auxiliary battery while trying to charge the main battery so more power is pulled from the auxiliary battery as it also tries to charge the defective main battery.
The end result is that the life span of the auxiliary battery is dramatically shortened and it too spits the dummy. This is usually when you are in the middle of nowhere because you have been driving through rough country at slow speeds and low engine revs.
There's lots more to it but I hope this will be a start and is of some help!
Regards.

tdi130dualcab
7th June 2004, 08:22 PM
I agree with drivesafe

a second battery needs to be properly "isolated" from the main battery. Idealy the "second" battery should be a deep cycle. this is very important to keep the beer cold!.

I make my own isolators for aux batteries but there are a few available on the market that do a good job. 8)

Mick-Kelly
7th June 2004, 09:04 PM
Thanks guys,
i'll try and sortout some pics of what ive got then see if we can figure out how to sort it. It looks like a very proffesional install
cheers
Mick

tdi130dualcab
7th June 2004, 09:13 PM
"professional" does'nt always mean they knew what they were doing.

simonit
8th June 2004, 07:49 AM
Hey tdi130dualcab,

You say there are some good ones on the market, could you give some examples. Am going down this path at the moment.

Cheers.

drivesafe
8th June 2004, 01:55 PM
Hi simonit, I manufacture auxiliary battery charges and have a web site. I would obviously like to sell you one but that’s not the reason for this message.
If you go to our web site, there is a Q & A section. If you go through that you will have a better idea of what you will need.
If you still have any questions email me or post it here and I will do my best to help you and you don't have to buy any thing.
Regards. 8)
traxide.com.au (http://traxide.com.au)

simonit
10th June 2004, 07:57 AM
G'day drivesafe,

Had a look at your website. I noticed on the SC40, that it doesn't isolate the main starter battery until it drops to 12v. Isn't this a bit low? Other ones I've seen do this at about 12.7v.

Shifter
10th June 2004, 08:40 AM
Just a couple of points for clarity: Don't deep cycle batteries require a higher charge rate to keep them fresh? Don't you really need a "smart" charging device to keep the voltage correct when charging a deep cycle and a standard lead acid battery? Don't deep cycle batteries dislike being disharged more that 50% for longenvaty.
I have a deep cycle battery in my motor home and treat it very carefully, with "smart" charging and increased voltage charging, never allowing ti to discharge more than 50% and it has lasted for years. They are an expensive item and require care and attention. From my experience it is normally charging devices, or lack of them, and care and attention that let them down!

Shifter.

drivesafe
10th June 2004, 04:41 PM
First cab off the rank, Sinomit you are comparing our system with a battery isolating type system.
The SC40 and SC80 are designed to do a lot more than just isolate the battery but in brief, they are designed to extend the operating time of your auxiliary battery by using the surplus power available from your main battery but at the same time they will monitor the common voltage and will disconnect the main battery while it still has enough power in it to start your vehicle a few times.
Next, after more than 15 years of designing these devices, working experience has the cut-out voltage at 12 volt as this is more than high enough to start a diesel and a petrol engine can go even lower.
Now Shifter for your query, deep cycle and cranking batteries charged in the same manor. The difference between them is that a cranking battery is made so that it can regularly support a very large discharge for up to 30 seconds at a time and would not be discharged bellow 80% and not be harmed, whereas a deep cycle battery would be damaged and it’s life span shortened if you were to do the same thing to it on a regular basis, but a deep cycle battery can be discharged well below 50% and still come back to full storage capacity after charging while a cranking battery would be damaged if you took it down anywhere near 50%
The trick to good health for both types battery is that you store they fully charged. In other words, no matter what you use, when you are finished, get them charged up again at the earliest possible time.
Now for charging either type battery. Here the main thing to attcheive is to have a high charging VOLTAGE and don’t wary about the charging current. The charging current can be as little as 1 amp , as long as the charging voltage is as close to 14 volts as you can get it.
At 1 amp it will take a long time to charge but by charging at 14 volts, the battery will hold more charge for a longer time.
Here is a simple and relatively cheap way to give you battery the best chance to charge properly. Use at least 8 B & S cable to connect between the main battery and the auxiliary battery and remember that’s for the NEGATIVE as well as the positive wire.
Regards. 8)

tdi130dualcab
10th June 2004, 06:30 PM
Hi simonit, sorry I havne't had time to find the one's I like on the marketplace at the moment {been working close to 24/7 reciently}. I agree with Shifter where the best way to go is to get a "smart charger", Ideally one that will charge to approx 14.5 volts untill the carrent dropps off, then maintain at 13.8 volts. Another thing to do if you are running a fridge (important to keep the beer cold) is to put a changeover relay on so when the vehicle is running the fridge is running off the vehicle system and the battery is left to charge without a load.

I go a little overboard with my system. One battery in the camp trailer for running lights and fans, one in the tray of the truck for running the fridge (for beer of course) backed up by a solar panel, one in the truck for lights, fans and radios etc and of course the one to run the landie.

The chargers I use are "smart chargers" as mentioned Shifter, that I built my self, but as with any tinker'r it is a constant work in progress and I don't have a finalised design, but even if the wiring is not perfect, (I.E. in removable batteries in the tray and on the trailer) the smart chargers will compensate for the loss in voltage in the wiring and boost the voltage accordingly for ultimate battery maintance.

Hope I havn't waffled on too much but for the best battery life and support going bush (we go for a few weeks without mains power at a time and I try to put my feet up and not move for a few days at a time......with cold beer) a "smart" charger is the way to go.

If you find something you are looking at let us know what is is and I'll have a look

Cheers

drivesafe
10th June 2004, 07:47 PM
Shifter I forgot to ask you, is your motor home used all the time or just for now and again trips. The reason I asked is that our Smart Chargers were designed for heavy duty use, although they will fit any monitoring situation and when we started the Smart Charger range years ago, one of the things we came across was the better makes of 12v fridges that had automatic low voltage cut-outs, were all set to 10.5 volts which is way to low for a cranking battery if you want to start something afterwards, but continually discharging a deep cycle battery down to this level is not a problem, whether it is to run lights or as tdi130dualcab puts it “to keep the beer cold”.
Our smallest Smart Charger, the SC40 has a programmable cut-out voltage which is set ex the factory at 12 volts but the customer or installer could change it to 10.5 for use with a fridge that does not have auto low voltage cut-out and we know that many of our customers have used cranking batteries as there auxiliary battery and we never received any feedback that indicates anybody had had any problems.
So it it depends on how you use and maintain the batteries as to how they will last and Shifter what ever you have been doing seems to work so keep it up.
One point I would like to raise about the charge voltage. When the voltage applied to a lead acid battery goes over 14.2 volts, a chemical reaction starts and this reaction has a type of cleaning affect on the battery’s plates ( this is a crude by simple way of putting it ). It is a good practise to do this to a lead acid battery for about 2 to 4 hours every 30 days but to do it continually will have an adverse affect on the battery.
By the way, if you go to some of the major battery manufacture’s web sites, you can get a wealth of info and also try the VW web site. They don’t make batteries but there web site used to have some great data relating to car batteries.
regards.
PS. Smart Charger is the trade name we you for one of out range of products that's why is used in the text above. 8)

Shifter
11th June 2004, 06:51 AM
Thanks for all the useful and discriptive discussion.
A bloke who lives in the NT - Broome, has written a couple of books about Motorhome / Caravan / 4x4 electrics, 12 & 24 volts stuff, which are excellent. I think his name is Collyn Rivers. He goes in to great discriptive length about "smart" chargers, regularors, batteries of different types, the whys and wherefores. If you plug in Collyn Rivers to Google he will appear as if by electricary! Well worth the read and purchase. some good Solar stuff in there too.

Shifter.

simonit
11th June 2004, 09:51 AM
Hey drivesafe,

I was intending on running 6 B&S cable (next size up from 8 I'm told) to a deep cycle in the back of the disco, but then run from the negative terminal through the floor to the chasis. Are you saying you should run both cables from the front?

Simon.

drivesafe
11th June 2004, 02:52 PM
Hi Simonit, yes and although it sounds like a good way to get a good earth, it's surprising how many vehicles have poor returns through there chassis because of paint or insulation or any number of other things that can reduce the conductivity. Most vehicles use the body work of the vehicle for a earth return for lights and other low current accessories and you may be ok using the chassis, but to guaranty that you will get the best possible control over the power supply, both when charging and when using the auxiliary battery,what ever size cable you use for the positive, use the same size for the negative. If you use the chassis you may find that although you have used 6 B & S, which has an 80 amp rating, for the positive cable, because there is the slightest bit of resistance through the chassis, you may only have a 10 amp return so your 80 amp wire will only be able to supply 10 amps. And another point to consider is that as the current requirements go up so does the resistance.
You can do a rough test to see if there is a resistance problem.
Take the leads off your auxiliary battery and connect a large load to the leads, say a few driving light globes. The measure the voltage between the main battery positive terminal and the end of the positive wire where you have the globes connected. Note the voltage. Next repeat the teat this time from the main battery’s negative terminal to the point where you have connected the earth to the globes.
If it is a good earth then the second reading should be lower or the same. If it is higher then the earth is no good.
If you do this test when there is both a positive and a negative cable then the readings should be the same.
Sorry I waffle on a bit but I find it is best to start how to do something and the REASON why.
Regards. 8)
One more point when running battery cable through a vehicle or to a caravan or trailor, put circuit breakers at both bettery positive terminals to prevent a fire in case of an accident.

Pedro_The_Swift
12th June 2004, 07:15 AM
Did I count right, Tdi130dualcab?
4 batteries? and solar!


what, no wind generator?
:wink:

and to keep this "technical"

what size batts for which purpose?

drivesafe
12th June 2004, 12:57 PM
With batteries, unlike a woman's view, the size does NOT matter.
When you are planning to add an auxiliary battery ( or 2 ) to your vehicle and/or caravan or trailer first decide where you are going to fit the battery and more importantly, how much space you have at the location where you want to fit it. The space alone my rule the size of battery.
If you have ample space then the next question is what type of battery.
Using a cranking type battery as an auxiliary battery under the bonnet when a winch is fitted the the vehicle is probably better as you can parallel the two batteries to use when wincing.
If you fit the auxiliary battery somewhere else and /or you will only be using it for house keeping operations, fridge, lights etc., one 12 volt deep cycle battery is better suited to this type of use, and if you have the room and need to run off the auxiliary battery for long periods of time you are better off fitting two 6 volt batteries wired in series.
Another consideration is what power will be available from your alternator.
That is not how BIG is your alternator?
If you know that you will be able to keep revs up above 1500 RPM ( this figure will very slightly from one type of vehicle to another ) for most of your driving time and most of the travelling is going to be in daylight hours then the good old 45 amp alt will work fine.
If you are going to be travelling at night with a few driving lights running and a fridge but you are still likely to be travelling at a good speed then it would be better to have a larger alternator.
If you are in a special situation where you know you are going to be travelling through rough country requiring low speeds for long periods and worst still doing it at night then it will not matter how big your alternator is, it will not be turning fast enough to cover the power that you are using let alone trying to charge either of the batteries.
A common situation that occurs in the Golf country in the wet, is for a vehicle to travel for hours and when it stops, the battery is flat.
At low revs and under load, an alternator will not be producing a high enough voltage as well as low current.
Good alternator voltage is 13.8 to 14.2. Lower voltage will not charge the battery ( s) properly and continuously high voltage will cook the battery ( s ).
You should work out these and other factors before doing any thing.
Regards. 8)

Shifter
12th June 2004, 07:20 PM
Your right on the money mate. Excellent advice. When my motor home is not in use I remove the house battery - deep cycle, and trickle charge with a smart charger. I made up an attachemet for a standard 12/24 volt battery charger. it keeps it fresh and in good nik. I need to add a higher charging alternator and a "smart" regulator and all my electricary problems are over. Same same for a 4x4 witha dual battery system.

Shifter.

tdi130dualcab
14th June 2004, 02:47 PM
Originally posted by Pedro_The_Swift
Did I count right, Tdi130dualcab?
4 batteries? and solar!


what, no wind generator?
:wink:

and to keep this "technical"

what size batts for which purpose?

O.K. to give a brief on the "4 batteries"

battery 1: stantard battery for the landrover.

battery 2: 28 Ah SLA (sealed lead acid) fits in standard battery compartment next to main battery. Used for light in tray of vehicle, running fans and charging torches and battery showers whilst at extented camps.

battery 3: 75 Ah deep cycle, backed up by a 60W solar pannel. The sole purpose in life of this battery (and pannel) is to keep the beer (I mean fridge running). This battery lives in a box in the tray of the landy....next to the fridge.

battery 4: 65 Ah deep cycle. Lives in the camper trailer and only gets charged while driving (or at home in the garage). This battery purpose in life is for lights, fans and (hevan forbid) portabile DVD in the camper.

Thats my little setup, gets well used....

Cheers

tdi130dualcab
14th June 2004, 04:12 PM
P.S. I'd fit a wind generator if I could, but I have enough height clearance problems as it is!! style_emoticons/<#EMO_DIR#>/laugh.gif

Pedro_The_Swift
14th June 2004, 07:15 PM
Not sure on the nonclementure Tdi130dualcab???

my battery is measured in hundreds of cca's
and you are talking about little numbers,,, 7.9 ,,,,,
are these amp hours?


this is interesting,,,,,
style_emoticons/<#EMO_DIR#>/biggrin.gif

tdi130dualcab
15th June 2004, 06:45 AM
Originally posted by Pedro_The_Swift
Not sure on the nonclementure Tdi130dualcab???

my battery is measured in hundreds of cca's
and you are talking about little numbers,,, 7.9 ,,,,,
are these amp hours?


this is interesting,,,,,
style_emoticons/<#EMO_DIR#>/biggrin.gif

Cranking batteries are usually measured in CCA (cold cranking amp's) and this is an indication of the instantanious cranking output power of the battery.

Deep cycle batteries are measured in AH amp-hours. they are not designed for cranking a vehicle over, but for running accessories. (example if you have 1 camping light that is rated at 1amp current draw, you could runit for a period of 55hours on a 55AH battery. 2 lights will run for half that time etc.)

Does that help?
cheers 8)

Mick-Kelly
16th June 2004, 03:56 PM
Rightio,
Took me forever but here it is.
Ive had another squiz under the bonnet and it turns out ive got a YUSA 67 525CCA's main battery with a DC 65, 65ah second battery. Now i assume that the DC stands for deep cycle. beside the second battery is a solenoid? with ST80 12V marked on it. The wiring runs from the second battery along the top of the chassis to the rear where it terminates in a fitted plug and two cigar lighters.
Now it was my understanding that if a second battery was fitted that a management component was required ie. little black box. If this is the case i cant find one anywhere in the engine bay of the vehicle. Therefore how is the charging system to the second battery managed. Secondly what sort of power flow voltage wise would be coming through the fitted plug at the rear. It has one horizontal slot above one vertical if that makes sense. Id like to get to the bottom of this so i can propoerly manage it and maybe set up some form of solar charger before i start messing around with fridges etc.
cheers
Mick

Pedro_The_Swift
16th June 2004, 04:16 PM
Originally posted by Mick&#045;Kelly
Secondly what sort of power flow voltage wise would be coming through the fitted plug at the rear. It has one horizontal slot above one vertical if that makes sense.
Mick

The good news Mick is, thats a proper 12volt plug.
around 12 volts and whatever current the cable can carry should come out the end.
a 10-15 metre 12 volt extension lead is a good idea too.

style_emoticons/<#EMO_DIR#>/biggrin.gif

tdi130dualcab
16th June 2004, 08:26 PM
Originally posted by Mick&#045;Kelly
Rightio,
Took me forever but here it is.
Ive had another squiz under the bonnet and it turns out ive got a YUSA 67 525CCA's main battery with a DC 65, 65ah second battery. Now i assume that the DC stands for deep cycle. beside the second battery is a solenoid? with ST80 12V marked on it. The wiring runs from the second battery along the top of the chassis to the rear where it terminates in a fitted plug and two cigar lighters.


You are right the DC 65 is a 65 Amp-Hour Deep cycle battery. Without more info i'd say that the ST80 is a standard 80 Amp sonenoid relay that is active when the engine is running. depends on how often you use the second battery as to weather you need to upgrade the system or not. My older rangie had the same system and it worked for me with my requirements then.

If you are looking at going solar there are otherthings to concider also. If your battery remains unloaded you can overcharge and cook your battery if you don't have a regulator on the pannel.

lots of things to consider..........

keep us informed as to where you are going with it all

cheers

Mick-Kelly
16th June 2004, 09:27 PM
At the moment the deep cycle dosent get used at all because im not running any accessories but i hope to change this with a waeco at some point after tax time. I was thinking of a solar charger as i am the type of person to go somewhere and set up a base camp and just go out in the boat leaving the vehicle with the base camp for up to a week. It seems a waist of all the available sun up here not to be doing something with it.
cheers
Mick

Mick-Kelly
16th June 2004, 09:30 PM
The suggestion of wind turbines earlier got me thinking about those spinning cooling vents you see on vans and dog trucks. Hmmmm a bank of for or so of them might crank out some power from an all day drive at highway speeds. :idea:

drivesafe
17th June 2004, 09:17 AM
Hi Mick-Kelly, before you do anything else, I would strongly recommend you put some protection on the wire running from the second battery to the rear of your vehicle.
This is a common oversight when so-called professionals wire up vehicles for dual battery operations.
Have a look at any vehicle on the road today and every single one has fusible links on the wiring coming off the main battery to supply power around the vehicle. Even though there is always one or more fuse boxes around the vehicle and many times one of the fuse boxes is located right next to the main battery.
The fusible link is there to reduce the chances of a dead short which can lead to a fire, occurring after and accident or if some does something wrong then working on the vehicle.
My own personal preference is to put circuit breakers on either end of the wire that runs between the two batteries but that's a personal choice and it also depends on the locations where the wire runs.
If you do decide to protect the wire coming of the second battery. Mount a circuit breaker as close to the battery as possible and then if you want to be sure, fit fuses on the other end of the wire. PS Use circuit breakers only on the wire running between the batteries because if you use fuses or fusible links, they will blow every time you start the vehicle.
You did not say what you intend to use the solar panel for or how big the solar panel is going to be.
If it is just for keeping the battery topped up then a small panel from one to 6 watts will do and you can make a great and cheap regulator using a diode and one or two festoon globes.
But if you are going to be using the panel to charge and supply power you will need a much bigger panel and a robust regulator.
BEFORE YOU DO ANYTHING ELSE put some protection on that wire.
Regards.
8)

Pedro_The_Swift
18th June 2004, 04:09 PM
Originally posted by Mick&#045;Kelly
The suggestion of wind turbines earlier got me thinking about those spinning cooling vents you see on vans and dog trucks. :idea:


and you all thought it was sarcasm! :wink:

fernockulated
18th June 2004, 09:34 PM
:? 8O dont ask me how they did it ,but was told of someone setting up a trailer with a rear diff housing with the centre still in it, hooked up via pulleys to an alternator in the trailer charging a second battery! 8O

drivesafe
26th June 2004, 07:21 AM
Hi fernockulated, that is not as far fetched as you me think. For many years old railway passenger carriages, when they had nothing more than basic lighting, had there lighting powered by a generator driven by a leather belt running around one of the carriages axles. So why not try it on a trailer, the technology is there? style_emoticons/<#EMO_DIR#>/laugh.gif
regards 8)

incisor
26th June 2004, 10:27 AM
Originally posted by fernockulated
:? 8O dont ask me how they did it ,but was told of someone setting up a trailer with a rear diff housing with the centre still in it, hooked up via pulleys to an alternator in the trailer charging a second battery! 8O

seen a heap of em over the years.

some even have a tailshaft that bolts directly to the drive flange and a housing over the alternator so it doesnt get full of crap.

one old guy i knew even had a dog clutch setup on his so he could have it spinning or not.

drivesafe
10th July 2004, 09:06 PM
On the subject of solar panels, can any one using them as a power supply for charging a backup battery post some details on how you have them mounted, how they are wired up and when do you use them, or if you prefer, send me a PM.
I’m interested in getting some feed back as I am about to start testing some new equipment and I would like to do it in as close a manor as it would be in the real world.
Regards

drivesafe
1st August 2004, 12:46 PM
Hi LandyAndy, I've just posted this to bring this to the top of the subject list and save you looking for it.
Regards. 8)