Additional Battery Setup - Not your usual system

[101RRS]

My 101 has a dual charging system for batteries. There is the main 24v alternator that charges the two starting batteries and runs truck electrics and there is a second 12v alternator that is used to power 12v stuff like LPG, radios, GPS and other 12v systems. Currently I just have an old 12v lead acid starter battery connected to take the load from the alternator. I need to set this 12v system up properly to run my fridge and maybe a portable winch.

So this is not the usual dual battery system in that I do not need to protect the starter batteries from discharge by the fridge.

So the questions

Should I just get one AGM or deepcycle battery to run the 12v side or split them across two batteries run in parrallel. All up I will be looking at something like 200Ah either in one battery or in two.

If I do run the two batteries in series should I draw power from both all the time or run on one and then switch to the other - in this case would it be worth while using a battery management system to keep usage and charging optimised in each battery. Will I get more out of the two batteries running on them individually or as a pair.

The 12v alternator is an old older type - probably about 40amp and I will be upgrading this to about 100 - 120amp later.

So you know, I have looked at removing the second alternator and using a reducer or battery charger off the 24v system but to get electronic equipment to do this is very expensive due to the high amps required and the current system is there, wired up and works - in addition I can jump start myself if the starters get flat. So I will stay with this 12v system.

Thanks

Garry

[bee utey]

A modern 12volt 85 to 130 amp alternator can be sourced relatively cheaply from 90's Commodores, all you need to do is swap the pulley. I personally have been using a semi-deep cycle Besco Extreme battery, part no. N70EX, it has been in continuous service for nearly 8 years. It may not be the most suitable for frequent deep cycling but is very robust and capable of being topped up. If I had 2 new batteries I would leave them in parallel permanently. The amp hour rating of any lead acid battery is highest with the lowest current draw. Also the lifespan is best with a lower total depth of discharge, so drawing both down at once gives the longest life.

[Blknight.aus]

Im a big fan of a lot of smaller batteries of the same type in parallel. Its usually cheaper in terms of the batteries and if you kill one you can easily drop it out of the system and still maintain some functionality.

Dont forget to make sure you have isolation of the right type on the new alternator when you get it and dont make it too big if you are going to run pure deep cycle batteries, While they can take a high current charge they last a lot longer with a lower current.

[101RRS]

I bought a single SuperCharge 105 ah dual purpose cranking/deep cycle battery. It will be charged by the spare alternator when in the vehicle and a 2600mah charger/trickle charger when at home. The only hard wired appliance is the analogue clock. Plug in appliances will the camping usuals - fridge, lights etc.

So the question is - when out camping etc what is the minimum safe voltage I can let the battery go down too before either switching appliances off or recharging the battery. Also any idea what sort of Ah would have been used from fully charged to the safe voltage.

If this battery works out I will get another and then work out the best way to connect them together.

Thanks

Garry

[Tombie]

Garry

Look into CAT 6v batteries and run them in series.... You'll get a ridiculously long run time from them :cool:

[drivesafe]

Hi Garry, and to start off, your 40 amp 12v alternator is the equivalent of a 60 amp alternator in a single alternator set up because yours is not power the vehicle’s fundamentals.

So you may not need to be in too much of a hurry to replace it until you see if it will or will not meet your needs.

Next if you are considering using an electric winch, if it draws more than 30 or 40 amps ( not sure about the current draw of your portable winch ) you need to fit cranking batteries.

Under normal use, dual purpose type batteries are an excellent choice but when high current winching is going to be done, deep cycle batteries can’t be used and I would not even use a dual purpose battery.

For the best all round life span of your batteries, permanently parallel for all the reasons bee utey posted and it doesn’t matter whether they are the same size, brand or age.

If you use a deep cycle battery, you can safely take them down to 30% SoC and as long as you charge them as soon as possible, they should give you a good operating life span.

With Cranking batteries, you can take them down to 30% SoC but they will have a shorter life span so it’s best not to take cranking batteries much below 50% SoC.

This chart will give you the voltage reference to find out the rough SoC of your batteries.

https://www.aulro.com/afvb/images/imported/2016/06/640.jpg

[simonmelb]

Garry

Look into CAT 6v batteries and run them in series.... You'll get a ridiculously long run time from them :cool:


Tombie - CAT have a 6V Calcium battery rated at 100AH that is very compact.

So if I join 2 of these in series I get a 12V 100AH battery ?

Cheers
Simon

[drivesafe]

Hi simonmelb, while using two 6v batteries in series will work perfectly, there are some potential drawbacks that you need to consider.

With a parallel set up, you can use any combination of similar or dissimilar 12v batteries to make up the amount of capacity you need and if any of the batteries play up, simply remove it. You can replace it when you get round to it or you can just leave the set up as is.

With a series set up, both batteries do need to be the same type, size, age and preferably the same brand.

In a series set up, if one battery plays up, you really need to replace both batteries or at least get exactly the same battery to replace the failed one.

Furthermore, while you source the battery, you will not have any 12v stored power and if you happen to be on that big trip around the paddock, you may find it next to impossible to get an identical replacement for some time.

Back to a parallel set up and if you do in a battery in, in the middle of the never, never, the first servo, K-Mart, Woolies or what ever, that you come to, you can buy ANY 12v battery and your up back to your normal capacity.

One more point, if you find that your existing battery capacity is a bit small, it's a lot easier ( and cheaper ) to expand a parallel set up than it is to expand a series set up.

[simonmelb]

Thanks Drivesafe

Makes a lot of sense ! - Im just looking where I can store 100 or 150 AH (or more) in my D2a for a big trip. I havnt decided whether to use the rear storage bins, under bonnet. I do like the parallel setup idea. I have a small generator as backup.

Cheers
Simon

[Signal1]

Thanks Drivesafe
Makes a lot of sense ! - Im just looking where I can store 100 or 150 AH (or more) in my D2a for a big trip. I havnt decided whether to use the rear storage bins, under bonnet. I do like the parallel setup idea. I have a small generator as backup. Cheers
Simon

Hi Simon,

FWIW, I have installed 2x Exide Orbital 50Ah batteries in parallel in the right rear bin of my D2. Works well and don't need to worry about venting or excess heat killing the batteries. Understand though that deep cycle batteries may not be suitable for your needs. I've installed a shelf above them inside the bin where my fuse box and relays are mounted.

Peter Phillips

[Tombie]

Hi Simon,

FWIW, I have installed 2x Exide Orbital 50Ah batteries in parallel in the right rear bin of my D2. Works well and don't need to worry about venting or excess heat killing the batteries. Understand though that deep cycle batteries may not be suitable for your needs. I've installed a shelf above them inside the bin where my fuse box and relays are mounted.

Peter Phillips

Pics?

[Signal1]

They are on the D2au site - http://groups.yahoo.com/group/d2au/photos/album/369563642/pic/list

Not sure if you need to be a member of the group to see them. Tonight, I'll move them across to my AULRO Gallery and add a few extras of the wiring done.

[Signal1]

Pics?

I've uploaded some more photos. The install isn't complete. I still have to mount the relays and wire up my reverse light. I have five thin gauge wire taped up into a type of loom running from the fuse box under the rear door plate behind the left bin and up to the centre console to auxillary switches. This allows me to switch things on a off whilst driving i.e. amp, fridge etc.

Message - AULRO Photo Gallery (http://www.aulro.com/app/showgallery.php/cat/1057)

[alanw]

I have not seen anyone on this thread mention AGM or gel matt batteries.

They have an advantage that they can be mounted in any direction - upside down - on their end or flat or anywhere inbetween. So are much easier to fit in awkward spaces. And they come in a variety of shapes - much more than conventional vehicle batteries.

They are tolerant of vibration.

And electrically they have massave advantages. It takes less power to charge them ( ie more efficient when charging), they store more power (abt 20 to 25% more for the same size cf a conventional battery) and hence deliver more power. They also hold their charge for much longer than conventional batteries. They work very well with solar panels - need a much smaller panel to charge them simply because the battery is much more efficient.

And expected life if charged correctly is 8 to 10 yrs.

I have had one as a second battery - set up 'loose' under the rear seat of a defender where it charges whenever the vehicle runs but can be removed easily for other uses away from the vehicle. I would never go back to a conventional battery again.

alanw

[101RRS]

This thread was started after following a number of other threads on various battery types - this thread was initially set up just talk about my particular circumstances and battery preferences.

Do a search as you will find heaps of threads on the advantages and disadvantages of the various types.

Garry

[Signal1]

:unsure: Sorry for the hijack Garry.

[101RRS]

:unsure: Sorry for the hijack Garry.

Not at all - is all good stuff - I got what I was after early in the piece and the following stuff has been of great value. Was just wanting to highlight that there are some really good threads on various batteries and that is why the ones he mentioned had not been discussed.

For me a AGM was just too much hassle to manage (nurse) and people have been having problems. I have decided to go a single 105Ah Super Charge Allrounder which will recharge slowly on my standard charger (albeit slowly) when home and will recharge reasonably quickly on my alternator. It also has a 750 cca if I need that in an emergency. Later if this battery works out I will be in a better position to either get another to match it or go a different system altogether. If I get the same battery I will put in in parallel and run both together. I am going to Jaycar to get a digital voltmeter this afternoon and will print off the chart Drivesafe put up and stick it next to the batteries.

All aspects of this thread has been of great value to me and I hope to others too.

Garry

[drivesafe]

I have not seen anyone on this thread mention AGM or gel matt batteries.

They are tolerant of vibration.

And electrically they have massave advantages.

Hi alanw, Signal1’s Orbital batteries are not only AGMs, they are genuine Automotive grade AGMs.

Most AGMs in RV use are NOT automotive grade and contrary to your post, these non automotive AGMs are not as robust as the standard type batteries that garrycol is already using.

Most AGMs will not tolerate as much heat, vibration, over voltage or over current charging that garrycol’s battery will take.

There are only a few AGM batteries that are direct replacements for garrycol’s battery and they are Exide Orbital, Odyssey and Optima, but ALL of these are much MUCH dearer.

And you have also posted some pretty exaggerated advantages about AGMs.

So I’d say garry was on the right track.

One point of caution, NO AGM battery should ever be mounted upside down. All AGM batteries have vents around the top edge, fitting them on their side or ends still leaves a vent in a safe position.

Mounting them upside down means all vents are blocked and you now have a ticking bomb on your hands.