second battery

Hi all,
I am about to have a second battery fitted to my 120 series prado and have been advised by some to fit a deep cycle and by others to fit a starting battery.The battery will be required to run a 50L waeco fridge.I have held the belief that I require a deep cycle ,however I'm beginning to doubt myself.What type of battery should I instal?
kman
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Reply By: MEMBER - Darian, SA - Wednesday, Mar 25, 2015 at 14:18

Wednesday, Mar 25, 2015 at 14:18
I'll leave those 'in the electro-know' re the best battery type, but keep in mind that if it is going in the engine bay, some deep cycle makers class their warranty as void if you put it in that very hot environment....the case can bulge !
AnswerID: 551586

Reply By: Glenn C5 - Wednesday, Mar 25, 2015 at 14:39

Wednesday, Mar 25, 2015 at 14:39
Is it going under the bonnet or in the cabin somewhere.
AnswerID: 551588

Follow Up By: kman1 - Wednesday, Mar 25, 2015 at 17:56

Wednesday, Mar 25, 2015 at 17:56
hi Glenn,
Battery is to be fitted under the bonnet.
kman
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Reply By: Rod W - Wednesday, Mar 25, 2015 at 15:24

Wednesday, Mar 25, 2015 at 15:24
A starting battery is all that is needed
AnswerID: 551590

Reply By: vk1dx - Wednesday, Mar 25, 2015 at 15:37

Wednesday, Mar 25, 2015 at 15:37
Fit another identical to the first.

Then you can swap them around if one goes belly up. As we did and we didn't replace the broken one until we got home. The corrugations shook the plates loose on it.

Amusing though because until it twigged. Every time we slowed or stopped we would look at each other and blame the other for the stink. Had to laugh though. Five minutes stop and we were away.

But then again we have three Allrounders under the bonnet because we sometimes like to camp for a bit every now and then and don't carry generators or solar cells. The two fridges work fine with no charging for up to three nights.
AnswerID: 551591

Reply By: Athol W1 - Wednesday, Mar 25, 2015 at 16:11

Wednesday, Mar 25, 2015 at 16:11
kamn1
As the second battery is going under the bonnet, and is going to be running a fridge, then the only choice is a flooded deep cycle as these are the only type of battery that will withstand both the heat AND the cycling that is required for the fridge and survive. It can also be used as a starting battery if the need arises.

Starting batteries will not survive with continuous deep cycle applications, and some will not operate your fridge for more than a couple of hours (if that) as they are designed to give that BIG INSTANT current flow that is required for starting purposes, not the slow continuous current flow that a fridge application requires.

Hope this helps.
Regards
Athol
AnswerID: 551594

Follow Up By: Member - Bigred13 - Wednesday, Mar 25, 2015 at 18:23

Wednesday, Mar 25, 2015 at 18:23
Yes agree with Athol ,deep cycle will stand being discharged more often than starting battery,a few times discharging and their life is shortened,so may not be reliable as a spare start battery just when you need it
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Reply By: HKB Electronics - Wednesday, Mar 25, 2015 at 16:41

Wednesday, Mar 25, 2015 at 16:41
I would suggest you use a marine pro as it has some deep cycle ability, should handle corrugations reasonable well and IMO is very good value for money.

Another Option would be an Optima but they are expensive for the money.

Other deep cycles that will tolerate under bonnet temperatures are around but you'll have to do some research.

One thing to keep in mind if your going to use a VSR setup is that a lot of deep cycles don't like high charge rates so again do some research before buying.

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AnswerID: 551595

Reply By: Member - Kevin S12 - Wednesday, Mar 25, 2015 at 21:29

Wednesday, Mar 25, 2015 at 21:29
Hi kman, I installed an 80amp deep cycle battery under the bonnet of my 120 and it is working perfectly after about 25,000k. It is hooked to a redarc solenoid to protect the crank battery. Will run 38litre engel for about 30-40 hours. Hope that helps
AnswerID: 551612

Follow Up By: Member - Paul B (WA) - Wednesday, Mar 25, 2015 at 23:24

Wednesday, Mar 25, 2015 at 23:24
I have a deep cycle under my bonnet as a second battery which generally runs flat overnight, even with the fridge turned up to around 5 or 6 degrees.

An autosparky mate told me its a waste of time if the alternator is charging the two batteries together as the deep cycle needs more volts going into it that the cranking battery, so once the cranking battery is charged, you won't get any more into the deep cycle, and therefore it never gets fully charged.

He reckons you either need a more sophisticated system that takes account of this, or a far simpler manual one, involving a boat switch, so that you're not charging the two different battery types together. Can anyone verify this?
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Reply By: oldtrack123 - Wednesday, Mar 25, 2015 at 23:42

Wednesday, Mar 25, 2015 at 23:42
Hi Paul
The Auto sparky does not know what he is talking about
I fthe batterries are both the sameTYPE Ie floooded wet cell batterries there is no problem with charging them both aFlooded wet cell LA starter & aFlooded wet cell LA deep cycle at the same time
In fact that is the way most are set up
What iisimportant is to have goos connections a heavy cable to the 2nd batterry
Also to protect the crank battery from discharging when the engine is not running & the fridge is, you should fit EITHER a VSR or an igntion contolled relay in the pos line to the 2nd battery
The size of the 2nd battery will need to be considered
That will depend on how long you hope for the fridge to run without the battery needing to be fuly recharged
Two question:
What TYPE of battery is the crank battery ?
Do you know what peak voltage the alternator charges to?


PeterQ
AnswerID: 551622

Reply By: Member - Crocles - Thursday, Mar 26, 2015 at 02:08

Thursday, Mar 26, 2015 at 02:08
Hi Kman1,

I think I heard somewhere that the later Prado's have a Smart Charge alternator, if so you may need a DC/DC charger to get the most out of your system and keep your auxillary battery charged fully.
Although I may be wrong. lol
AnswerID: 551625

Follow Up By: HKB Electronics - Thursday, Mar 26, 2015 at 10:25

Thursday, Mar 26, 2015 at 10:25
Prado's have a high compensation type alternator fitted, installing one of my booster diodes overcomes the problem of low charge voltage on these vehicles.

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