Dual battery confusion

Submitted: Thursday, Jul 15, 2004 at 12:14
ThreadID: 14681 Views:2446 Replies:12 FollowUps:11
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Users have heard the question one million times but here goes.

I have a 98 Prado and am going to run a 40 litre engel fridge, I have been given a pefectly working gel type deep cycle battery, the problem is I have contacted the local ARB to fit it and he says that I dont need this type of battery. He told me that they are fitting cranking batteries instead of deep cycle.

I have a mate that swears that a deep cycle is the go.

I dont know what to believe, the mate or the arb dude, is that just a way to sell me another battery or what?

What are other 4wders using. I will be only running a fridge and some lights off the 2nd battery.
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Reply By: madcow - Thursday, Jul 15, 2004 at 12:30

Thursday, Jul 15, 2004 at 12:30
Gee it would be safe bet to say that the deep cycle battery is the most suitable for what you say you are going to run off it. If you had a winch i would look at a cranking battery instead of a deep cycle. You have gotten it for nothing and have nothing to lose and might as well use it!

AnswerID: 67886

Follow Up By: steve75 - Thursday, Jul 15, 2004 at 12:40

Thursday, Jul 15, 2004 at 12:40
The only problem I got is its pretty big, they might charge me an arm and a leg to fit it.
I wont be running a winch.
FollowupID: 328575

Follow Up By: bruce - Thursday, Jul 15, 2004 at 13:07

Thursday, Jul 15, 2004 at 13:07
Why not get a quote from them and someone else first on just how much to fit that battery...it sounds the way to go in my opinion...dont let them sell you something you do not really need just because they reckon every one else is using it...cheers
FollowupID: 328576

Follow Up By: Bonz (Vic) - Thursday, Jul 15, 2004 at 18:10

Thursday, Jul 15, 2004 at 18:10
or...fit it yourself
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FollowupID: 328596

Follow Up By: Brew69(SA) - Thursday, Jul 15, 2004 at 21:14

Thursday, Jul 15, 2004 at 21:14
Simple to fit yourself mate
FollowupID: 328628

Reply By: Member - Jeff M (WA) - Thursday, Jul 15, 2004 at 13:51

Thursday, Jul 15, 2004 at 13:51
If you are mainly doing weekender then the deep cycle is the best IMO. You can run it down more on the weekend, then during the week of driving it get's a good chance to charge up ready for the next time.
Basically with deep cycles, you can flattern them more without casuing as much damage as you would to a cranking battery.
This is because the deep cycles has less plates and they are thicker so are a little stronger. It means you cannot draw as much current and it takes longer to charge. From my understanding the more cells a battery has, the quicker it charges.
Also with most dual battery setups you will never get the deep cycle to 100% charge. It'll just linger a little lower than that. But it doesn't really matter as you can run it for longer even if you take that into account.
AnswerID: 67895

Reply By: crowie - Thursday, Jul 15, 2004 at 14:23

Thursday, Jul 15, 2004 at 14:23

I think this is an ARB policy. I'm just been looking at an article in the July 2002 4WD Monthy magazine relating to this subject. The author was John Vanc den Eynden who at that time headed up ARB's NSW operations at Moorebank.
Quote: "Deep -cycle batteries are designed to be discharged and then fully recharged on a regular basis. Unless your a National Parks ranger or a tour operator, your second battery is likely to spend most of its life doing basically nothing - and that on of the best ways known to kill a deep-cycle battery"

I fall into the category of occasional camper. Around one long trip away and a few weekenders through the year. Despite this, I run a deep-cycle but use it constantly. My UHF CB is hard wired to it and it is runnning basically all the time with the volume turned down. I have power points around the vehicle and charge my phone, digital camera batteries and run a small cooler fridge at least once a week off it just to draw power. You can also wire the car audio system to run off it." Don't even consider connecting a winch to a deep-cycle however.

It basically depends on the type of use your going to put the battery to. eg bushbashing and lots of winching on a weekend mixed with the occasional weekend of camping you might be better of with a second HCD (starting battery). If your retired and intend spending lots of time camping, running lights, fridges etc the deep-cycle is the way to go.


AnswerID: 67896

Follow Up By: V8troopie - Friday, Jul 16, 2004 at 01:50

Friday, Jul 16, 2004 at 01:50
Cowrie, that quote in your first paragraph is utter nonsense. That author ought to read a bit more about deep cycle batteries before printing such rubbish.
FollowupID: 328658

Follow Up By: Member - Jeff M (WA) - Friday, Jul 16, 2004 at 12:43

Friday, Jul 16, 2004 at 12:43
Sorry Crowie, I've got to agree with V8troopie, complete crap.
Any lead acid battery being constantly charge with no load will eventually dry out and needs to be regulary topped up with distiled water. (they all should be anyway). But my deep cycle works everyday anyway! It runs the car stereo, internal lights, air horns, CB, GPS etc etc etc.
FollowupID: 328675

Reply By: Moose - Thursday, Jul 15, 2004 at 14:47

Thursday, Jul 15, 2004 at 14:47
Steve - you have a free battery so use it for now. If you find you don't like it you can always change to another sort later. Get a few quotes to fit them or have a go yourself and save a few dollars. Look on the net - you'll find wiring diagrams - it isn't that hard.
As for the cranking v deep cycle issue I have used deep cycle for many years now believing they were the best but next time I'm going to cranking. Why? Because the cranking battery can easily be recharged by the alternator whereas once you flatten a deep cycle they can't be recharged effectively by the vehicle. They can only be recharged by trickle charging over an extended period of time (ie days, not hours). This was directly from the bloke who sold me the latest deep cycle and certainly helped explain the problems I'd had with past deep cycles. Unfortunately I only found out after I'd bought it when I thought it was cactus and went back to see what was wrong. His words were along the lines of "mate once you've run that deep cycle down you could drive from here to Bourke and back and it still wouldn't be charged" (I'm in Brisbane). As I don't have solar panels to extend battery life I believe for my use a cranking as the second battery would be best.
There are many factors involved in having the most suitable battery and your individual useage pattern will determine which is best. But as I said you have a free one so use it.
AnswerID: 67900

Follow Up By: V8troopie - Friday, Jul 16, 2004 at 02:11

Friday, Jul 16, 2004 at 02:11
More myths about deep cycle batteries here. Consider all the yachties, having banks of deep cycle batteries on their boats. They recharge them by fitting a big alternator to the boat engine, capable of dumping lots of amps into the battery during the hour or so they run it daily while sailing. Yes, this current does drop off as the battery fills up and it DOES take a longer time (than with a starting battery) to put in the last 10% of charge but its not at all like stated above.
However, you have to make sure the aux battery gets the FULL voltage from the alternator, any drop via a diode or electronic isolator might lower that initial current considerably. A relay type isolator would be ideal, coupled with sufficient size wiring to handle the full alternator current.
You get 90% of the charging done in a reasonable time if you treat the deep cycle battery right.
That means NOT running it flat - ever -, charge it up when it gets down to 50% charge at the latest. That may mean a bigger capacity battery and I suspect there lies the main problem for most disappointed 4WD deep cycle battery users. Do your power consumption sums for not lower than 50% discharge and you'll get years of good service from the battery. In other words, for a 100Ah battery, treat it as if there were only 50Ah available for use before having to recharge it.
FollowupID: 328659

Follow Up By: Mick - Friday, Jul 16, 2004 at 09:20

Friday, Jul 16, 2004 at 09:20
Aimed at v8 troopie, and moose.
Most battery distributors - not sales outlets, tell us that you should only drop a deep cycle to 1/3 of its storage, otherwise they loose the capacity to recharge and sometimes need to be left on a charger for weeks at a time to bring back the efficiency.
We reccomend Cranking batteries, and if the battery is not used, then put a calcium cranking battery in to keep up the charge.
As moose says above the deep cycle cannot be recharged by avehicle alternator, well you can if you drive for 8 hours every day and camp overnight, but then if you stay in one spot, it becomes difficult to charge it, which is why people HAVE to carry solar panels to supply the trickle charge over a period of time.
A cranking battery can be charged within an hour or 2 depending on how much load has been on it with an automotive alternator, which is why we build our Outback Battery Chargers!!
Take it easy, happy camping.
FollowupID: 328667

Follow Up By: Member - Jeff M (WA) - Friday, Jul 16, 2004 at 13:12

Friday, Jul 16, 2004 at 13:12
I agree with V8Troopie again. I have an 80amp/h deep cycle and a 90amp alternator on the surf. The only problem I have is a .1 voltage drop from my electronic isolator. It stops my deep cycle from charging to it's full charge of 14v. It sits at 13.9V with my normal load. It will register 14v if I take everything of it and let it rest.
But he is spot on. It's not that Deep Cycles take longer to charge, it's just that they require more AMPS to charge. Because of the bigger plates in them you have to give them more oomph. If you don't, they will take a long time to charge. If mine drops down to about 11.5V and then I drive a couple of hours home, it'll be back to normal (or just under). Of course if I really hammer it, I can whip out the battery charger when I get home and give it a good oon. Then it will register 14-14.1 volts for about a week until it finally catchs back up and sits at about 13.9V no matter what I do to her.
If you have a good alternator, the deep cycle should not be a problem, my mate has a Ferzoa which probally doesn't have a 90amp alternator so he uses an Odesey and it work brilliant for him. I didn't want to spend $500 on a battery so I spend $100 on a powercrank deep cycle and am as happy as a pig in sht.
FollowupID: 328680

Reply By: Dave from Fraser Coast 4WD Club - Thursday, Jul 15, 2004 at 15:47

Thursday, Jul 15, 2004 at 15:47
I'll never fit another deep cycle again!!

Exide extreme is my choice.

Then again, you may as well use the battery you have, until you kill it, then buy another!
AnswerID: 67906

Reply By: Magnus - Thursday, Jul 15, 2004 at 16:22

Thursday, Jul 15, 2004 at 16:22

Here is some homework for you. I suggest you search around on the site below


and then re-resd the various posts and draw your own conclusions.


AnswerID: 67910

Reply By: Member - Barry W (VIC) - Thursday, Jul 15, 2004 at 21:35

Thursday, Jul 15, 2004 at 21:35
Hi steve
We travel very often and have always used a cranking battery and prior to us now enjoying our 4x4 adventures we had a 33ft yacht which we cruised around on for several years again using cranking batteries never had any probs, having said that if you don't constantly charge the cranking battery it will die very quickly for our camping trips we use a christie Engineering 12 volt 55amp battery charger attached to a 50cc Honda motor a very good unit for those longer stays doesn't need to run long to fully charge the battery.
A good read regarding this topic is Collyn Rivers Motorhome Electrics check out
good luck
AnswerID: 67980

Follow Up By: Mick - Friday, Jul 16, 2004 at 09:07

Friday, Jul 16, 2004 at 09:07
Geeee those Christie battery chargers are good!!!
FollowupID: 328665

Reply By: Martyn (WA) - Thursday, Jul 15, 2004 at 21:59

Thursday, Jul 15, 2004 at 21:59
I've put a dual battery system on my GU I've gone for a hybrid battery which is supposed to be a compromise between the deep cycle and the cranking battery, I also run a winch, like others I've wired up a couple of my "normal" accessories to the auxillary battery plus when I don't have the fridge on I've wired up one of those old mechanical electric clocks that I plug into the back socket, I store it inside the side pocket, this keeps a very slight discharge load on the battery, it's worked for me so far. I got my battery and advice from the company you mentioned.
Keep the shiny side up

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AnswerID: 67983

Reply By: Eric Experience. - Thursday, Jul 15, 2004 at 22:05

Thursday, Jul 15, 2004 at 22:05
If the gel is good use it. the statement about a deep cycle battery needing to be dishcharged and then fully charged is incorect, a deep cycle lasts longer if it is kept charged all the time but it can be dishcharged if necessary. The ARB person who made the comment is confussing the gell cell with a nikad. It is important to remember that ARB agents are not all trianed technicaly they are sales people. Eric.
AnswerID: 67985

Reply By: mr diamond - Thursday, Jul 15, 2004 at 22:23

Thursday, Jul 15, 2004 at 22:23
gday steve.
i use a marine battery.
good for charging/discharging.
high amp.
great for cranking battery.
can sit around for ages doing nothing.
sorry it dosnt answer your question
but im thinking arb are full of it.
AnswerID: 67992

Reply By: Member - Ken - Thursday, Jul 15, 2004 at 22:25

Thursday, Jul 15, 2004 at 22:25

Moose and Eric are on the 'money'here.

Firstly - relating to size- (my favourite subject) this governs whether or not you can use the battery you allready have. (Gel type). You have to determine the max size battery carrier that will or can be fitted to your vehcle.

Ask ARB what is their standard/largest they can fit to your vehicle.

(I strongly suggest you get the biggest sucker of a carrier that will fit).

If your current Gel deep cycle fits - excellent. If not and you have to buy a different profile battery to fit, then you can make a decision on a 'whatever' battery that suits your needs.

Secondly - if you can ,use what you have (for free) and if required upgrade later.

Have a good one

Ken Robinson
AnswerID: 67995

Reply By: steve75 - Friday, Jul 16, 2004 at 09:21

Friday, Jul 16, 2004 at 09:21
Thankyou all for your help. I will add this battery I have, and see what happens.

As for fitting it myself, im a little worried that I could make a mistake and destroy something, im not the best when it comes to DIY electricals.

AnswerID: 68017

Follow Up By: -OzyGuy- - Wednesday, Jul 21, 2004 at 10:48

Wednesday, Jul 21, 2004 at 10:48
get a second oppinion from a qualified Auto Sparky - Who drives a 4x4 with a duel battery system installed......

There are plenty of sites on the Net about the good, bad and indifferent of various batteries...

The facts are ..
'High Cranking Amps' are used for specifing the power available for Cranking/Starting batteries ...eg '720CCA'

'Amp Hours' is used for specifing the power available for 'STORAGE Batteries' ...eg '80Ah'
Deep Cycle batteries also have their 'reserve Capacity' stated on the battery ...eg '145 Minutes' (Delkor 80Ah)

Both batteries look similar on the outside however are built different inside, hence the very different characteristics in the chemical release of the electrons causing the power to be sustained over a longer period of time in the Storage (deep cycle) battery and also longer recharge times, because that is the chemical characteristic of Storage batteries.

You will have no problems with your battery, IF - you keep it charged when not in use.
A good trickle charger (<$2oo) would be a bonus if you remove the battery from the vehicle and keep it on charge when not in use.
FollowupID: 329283

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