Another battery question

Submitted: Wednesday, Jul 03, 2013 at 21:07
ThreadID: 103084 Views:1857 Replies:6 FollowUps:12
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Hi guys and girls,
I have a question about battery's which I'm sure have been covered but I can't find any real info about it.
Question: am I better off running 1 large battery, 2 medium or say 5 small AGM battery's? What is a better way to go about it? I basically only free camp and have solar to well and truly keep the power up.
Any info would be great thanks.
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Reply By: olcoolone - Wednesday, Jul 03, 2013 at 21:17

Wednesday, Jul 03, 2013 at 21:17
It comes down to price and physical size...... two 50ah batteries would cost more and take up more space then one 100ah battery.

In some applications you may have to run two 50ah batteries as you can not physically fit one 100ah battery into a particular location...... or you may have to go to two different size batteries to satisfy you power needs.

Having said that I'm a big fan of multiple batteries....more to do with capacity and reliability then anything else.

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Follow Up By: allanw - Wednesday, Jul 03, 2013 at 22:39

Wednesday, Jul 03, 2013 at 22:39
I was having a few issues with my battery set up a while back and enquired about some 200AH batteries and they only came in 6v form because of their weight and size. I ended up getting a 150AH battery but its about 30% longer than the standard 100AH battery and a mother of a thing to lift out of the camper.

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Follow Up By: olcoolone - Thursday, Jul 04, 2013 at 12:20

Thursday, Jul 04, 2013 at 12:20
We do a far bit with the Powersonic range of batteries due to their quality and they come in over 50 different combinations of ah and size across two rangers.

When running 6v batteries you only get the ah rating of one battery if using in a 12v application.

Weight can be a big problem especially lifting them in and out of tight spots.
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Reply By: Member - PJR (NSW) - Wednesday, Jul 03, 2013 at 22:27

Wednesday, Jul 03, 2013 at 22:27
Another option Jason.

We have three 105AH "Allrounder" batteries under the bonnet. They are separated with one as a crank/main battery and the other two paired for camp accessories and any "extras" that we put in the car. We have a 200 amp Redarc isolator between the crank and other two paired batteries.UHF radio, inverter and any charging plus the fridge/s and any camp lighting etc is run of the accessory batteries.

For short trips we install a single 40L in the car. For longer trips we add a 21L as a freezer. This gives us at least two days stationary running off the paired accessory batteries.

Cost was not considered as the trip was more important.

We do not tow anything.

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Follow Up By: Ross M - Wednesday, Jul 03, 2013 at 23:05

Wednesday, Jul 03, 2013 at 23:05
G'day Phil

3 x 105 ah under the bonnet, that is in the realm of a Hybrid vehicle. Do you use a dc motor just on light cruising? Just joking.

I'm just envious as I can only fit the OE battery under the bonnet. Maybe only a small sealed battery somewhere.


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Follow Up By: Member - PJR (NSW) - Thursday, Jul 04, 2013 at 06:57

Thursday, Jul 04, 2013 at 06:57
Mate, there isn't room left for a toothpick. But at least we can still get to things. ARB had a carrier that fitted just in front of the firewall on the left behind the electronics. And the Redarc and fuel filter mounted on the side of it. Just lucky. They did a mates, who also has a 100 series, as

Nothing like pulling a chocolate coated ice cream out of the freezer at Poeppel corner and watch the reactions. Love it!!!

It also means that we can go bush for four weeks and not worry about fresh (frozen at least) food. We could never get the cryovac stuff to work for us.

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Follow Up By: Member - Frank P (NSW) - Thursday, Jul 04, 2013 at 11:56

Thursday, Jul 04, 2013 at 11:56
We do it slightly differently in our Prado and Karavan.

There's a conventional cranker and an Allrounder 105Ah under the bonnet. The Allrounder runs the car fridge, which we use as a freezer (the Karavan has the fridge). It is charged by a DC-DC fully programmable smartcharger (Ranox) with max current set to 10 amps (10% of C).

There is a Redarc SBI to isolate the Allrounder and its charger when the engine is off and also a load-switching relay that switches the freezer to run off the alternator when the engine is running, and off the Allrounder when it is not. This allows the Allrounder to be charged at its ideal rate with no load connected.

We have another Ranox in the Karavan to charge it while travelling - that one is set to its max output of 25A. When we go bush we run the freezer off the Karavan batteries (320Ah). We have enough portable and fixed solar to run the Karavan and the freezer indefinitely as long as the sun shines, with generator backup.

Like Phil, we are self-sufficient for about a month and enjoy ice cream desserts for as long as the tub lasts :-).


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Follow Up By: olcoolone - Thursday, Jul 04, 2013 at 12:11

Thursday, Jul 04, 2013 at 12:11
Good to see someone using a Ranox...... the two Alans did a good job with them and IMO they are still the best DC-DC charger made, they had many good ideas and functions.

Sadly no longer available.
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Follow Up By: Member - Frank P (NSW) - Thursday, Jul 04, 2013 at 12:16

Thursday, Jul 04, 2013 at 12:16

When my original cranker died a natural death I was going to replace it with an Allrounder because I was happy with my Allrounder aux. I decided against it because it wants a high absorption voltage (15.5V) to get fully charged which the alternator cannot supply, and a low max charging current of 10A, which the alternator will exceed every time if the battery is down a bit.

I imagine your Allrounder cranker would be in a similar situation, so just wondering how long it's been installed and how is it faring?

If it's lasted three years or more I will re-consider my view.

Also, if you have a winch do you winch off the aux Allrounders or off the cranker?




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Follow Up By: Member - PJR (NSW) - Thursday, Jul 04, 2013 at 13:13

Thursday, Jul 04, 2013 at 13:13
Hi Frank.

I think the first Allrounder went in about two years ago. It replaced one of the twin batteries that came with the car. The next two went in 15 months back. They got almost fully discharges recently when someone left the positive feed off and it shorted to a clamp. Luckily the Redarc isolated the lead. They got down to 8V. I gave them a trickle charge overnight and they load tested okay last Monday.

When winching I plan to bring all three batteries in to play. I have a switch on the console to override the Redarc action.

I have not used the winch with any Allrounder battery installed. Just the original two that came with the car. I seem to find trees in the desert a bit hard to locate and it's a lot easier and neater with the Maxraxs. Haven't been stuck in the high country yet even though it has been close sometimes.

Frank you had me going for a while there. I even Googled "Karavan" to see if it was a special model or manufacturer of caravans. If that spelling was planned to trick me - well done. Gotta have a laugh mate.

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Follow Up By: Member - PJR (NSW) - Thursday, Jul 04, 2013 at 13:22

Thursday, Jul 04, 2013 at 13:22
I meant to add Frank that I am thinking of an alternator upgrade. Not convinced that we need it as yet.

The current setup has worked perfectly on two month long drives. One up to the gulf and back and another into the center and home via the Simpson.

Neither fridge voltage got below 11V. I have external monitors on both for internal temperature and a voltage pickup from the innards of the fridge's electronics package. We had a couple of three night stops on both trips.

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Follow Up By: Member - Frank P (NSW) - Thursday, Jul 04, 2013 at 14:06

Thursday, Jul 04, 2013 at 14:06
Krikey, Phil!

I just googled "Karavan" and got 10 pages of hits. The first relevant one I found is this one, on the 4th page. Did you find it? :-) Ours is an older model - doesn't have the bells and whistles of the newer ones, but we love it.

Re the alternator upgrade - A bigger alternator will pump out more amps to batteries that are well down. Your Allrounders really only want about 10A, three in parallel about 30A. They are probably getting more than that already. Also, the alternator voltage is below what the Allrounders want for a full charge (if available they like 15.5V before going into float). My feeling, FWIW, is that if you stick with Allrounders an alternator upgrade may not be the best thing for your batteries. The two auxiliaries in parallel could benefit from a 20A or 30A DC-DC charger with a calcium profile, though. Unfortunately those don't come in a toothpick formfactor :-), so perhaps it could fit under a seat, like my Prado's Ranox.

The problem with these batteries that like (and get) a low charging current is that it takes a lot of driving to charge them if they're down, so you might be better off with your present system - as you said, it has worked perfectly when called upon to do so. But the high amps and low voltage might be affecting battery life, and that's why I was asking about how long they'd been there.

I try to keep my batteries above 12V - that's about 50% discharge on the Karavan's AGMs, similar but different for the Allrounder. Not always successful, but that's the aim.




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Follow Up By: Member - PJR (NSW) - Thursday, Jul 04, 2013 at 15:46

Thursday, Jul 04, 2013 at 15:46
Yep That link makes sense. I just googled "what is a Karavan". Totally different planet.

We got rid of our tow as it limited where we went and buggered if I am going to spend the day worrying about it still being there when we return after an uninhibited drive.

Maybe that's why I didn't even think of the Kimberley.

I will also leave all the stuff about batteries to you. I trust the bloke that we got the batteries from and that's good enough for me.

I am also of the mind to "leave it alone" as far as the alternator is concerned. The battery bloke said leave it and the auto electrician said it may be worth looking at. Which one will win? Maybe the battery bloke as that's more his speciality.

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Follow Up By: Member - Frank P (NSW) - Thursday, Jul 04, 2013 at 16:40

Thursday, Jul 04, 2013 at 16:40
Ok mate.

I didn't mean to lead you on a wild goose chase with "Karavan" but if you thought I did and got a chuckle out of it, then things aren't too bad, are they?

Agree re the tow. We love the van and although it goes a lot of places, it can't go everywhere we would like it to. But without it there would only be one or neither of us out there.

Have a good one.


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Reply By: Sand Man (SA) - Thursday, Jul 04, 2013 at 07:23

Thursday, Jul 04, 2013 at 07:23
As well as the physical size of batteries, you also need to consider the weight, especially for AGM type batteries.

I have 2 80Ah AGM batteries in the camper, one on each side, at the rear of each wheel arch.

I also have a 100Ah battery contained in a "Flyer" in the rear tub of my vehicle and boy, is it heavy. This one I don't regard as portable and it is my main auxiliary battery, tasked with running the Engel and virtually nothing else.
I can only image how heavy a 150Ah AGM battery would be!

Multiple batteries installed in a camper or van, make good sense, both in weight distribution and multiple cell capacity. If one battery has a problem and you notice it quick enough before it drags the other battery or batteries down, you can simply disconnect it and carry on with a diminished Ah capacity for a short time.


I'm diagonally parked in a parallel Universe!

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Reply By: Allan B (Member, SunCoast) - Thursday, Jul 04, 2013 at 09:20

Thursday, Jul 04, 2013 at 09:20
Jason, connecting two (or more) batteries in parallel is essentially OK.
There are some considerations however:
1) Two smaller batteries occupy more space than a single larger one. However they may be easier to stow and handle.
2) If one of the two begins to fail it will tend to discharge the other but that is no worse than a single larger battery failing. In any case there is an option to disconnect the ailing battery and continue with the good partner.
3) Balancing the charge to the two batteries is perhaps the biggest issue, particularly if one battery begins to age prematurely. In my setup the two auxiliary batteries are individually charged by two Redarc BCDC1220 chargers which attend to the needs of each battery, then when the engine is off, a relay places the batteries in parallel.

Certainly the two paralleled batteries should be of the same type and capacity. Having more than two batteries in parallel probably compounds the negative factors.

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Reply By: Jason S8 - Saturday, Jul 06, 2013 at 10:50

Saturday, Jul 06, 2013 at 10:50
Wow! thank you guys. Great info.
I think I have decided to go two 250a deep cycles in the van and I already have a 105 in the ute. Pretty sure this will keep us going lol
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Reply By: Daisy G - Thursday, Jul 11, 2013 at 16:08

Thursday, Jul 11, 2013 at 16:08
How much is the wattage of your solar panel? Do you mean that you are taking a solar panel as supplymentary. I recommend you to run the computer and light inside by the power generated by the solar panel. A 250W solar panel can provide 5 to 6 hours working of the lights insides, which will saving your battery. Off course what I mean it is you are using energy efficient lighting sources, like LED light. Go to korring lighting to see the camping light series, besides a lighting online store: which has the newly launch LED products in Australian market.
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