2 batteryes management

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Aug 13, 2016
Hi guys, I have a problem and I don't know from where to start.
My 2002 hdj100 rig have from factory 2 battery and last night was cold, -3 degree celsius and the dude doasn't want to start. 2 varta batteries 95Ah....
I understand that I have a 2 battery management, original toyota and when you want to start the engine, will take energy from both batteries and in running mode 1 main battery will keep the energy only for the engine to start, and the other battery for auxiliary stuff. I check the voltage and both have same value....I recharge with a robot and after 1 hour both batteryes have same voltage, exactly.
Do i have to buy a battery management to can keep the fridge on when the engine is stop? to don't have surprise when I want to start the engine?
Thanks in advance
As far as my knowledge goes, the two factory fitted ones that you have gives you the 24V that the 100 series needs to start - both of them. If you want to run other auxiliary items like a fridge, it needs to run from a 3rd auxiliary battery which is connected with a dc/dc charger to the main batteries. The dc/dc will regulate the charging. During driving the alternator will first fully charge the main batteries and then divert the charge to the aux battery. It will also ensure that when the fridge "kills" the aux battery that it will not draw further power from your main batteries so that yiou do not have starting problems.
HDJ100 is a 12v system (Two batteries are connected in parallel - same voltage extra capacity)


This is how a dual battery setup on my HDJ101K-RNPGZ

I did not use the ironman brand but something similar from the marine dual battery setup (Other types of dual battery management)

You will need to manually switch your accessories to the Auxiliary battery and all new electrical like fridge to be wired to the aux. If you want to use the rear cigarette power outlet you will need this mod to keep it on after the keys are out.

Depending on the year of your Cruiser you have to find out which battery goes to the starter (make that your mains) and some electrical accessories are tie to the same starter battery.

More explanation here
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Thank you catz, amazing explication. But I can't acces that link, I don't have account and to make one, they ask me about invitation :(

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