Dual Battery Setup

[Conrad]

Hi all,

Finally after a long time I have installed the rear storage unit in my JK and am about to palm out the cash for a second battery and dual battery system.



This is the battery I am thinking of, great amp hours to run accessories, easy maintenance and no gassing or leaking.


This is the dual battery system I have been looking at, 275amp so should be more then enough but am attracted to being able to crank the engine off the battery in the back if needed.
http://www.ironman4x4.com/html/motorised275amp.html

I am running an ironman 50L ice cube which pulls about .7 Amp/hr and will be running all the light for my camp sight off it. I will also be running an inverter to charge a portable vacum, air bed pump etc.

If you can see anything wrong or think I should do something different, let me know.

Conrad

[redfox355]

Wowsers, that's a big battery! Are you sure that the surrounding sheet metal that you've cut into can hold that much weight?

What gauge cable will you be running to the rear? It's a pretty long distance, and it'll have to be pretty decent especially if you want to jump start off it. You will want to make sure it's well insulated from rubbing through due to vibrations etc. If you are going to jump off it, you can't fuse it, so you don't want it to short out on the body. I'm going to go the dc-dc charger option when I install mine. Lower current thinner gauge wires which are easier and more safe to route to the back.

[aido_3927]

You can't fuse a starter lead at all? Surely there's some kind of protection available? I'd never feel safe without a fused power lead!

[MidnightMods]

The 13.7volt charging might be a problem, I dont think I ever see my JK get that high and stay above that voltage, normally sits around 13.5volts

[MightyMouse]

Just wondering..... these parallel battery charging systems, how do they cope with batteries that require different charging rates ?

I note the spec for the battery listed states less than 45A cyclic charging current.... and that may not be what the vehicle alternator and charging system provides.

From an outsiders perspective these solenoid based "dual Battery systems" seem cheap but offer none of the features required to properly charge a second battery.

[redfox355]

Originally Posted by aido_3927

You can't fuse a starter lead at all? Surely there's some kind of protection available? I'd never feel safe without a fused power lead!

Usually you don't fuse starter leads. If you really want you can try and fit a really big circuit breaker, but considering that you will be drawing in excess of 500A when cranking, that'll be a big breaker.

Generally if it's going to be a cranking assist battery, it's best to have it in the engine bay very close to the main batt and joined with heavy gauge high current leads/solenoid. If the leads aren't too long and well protected, then the risk is low. If you are really paranoid, fit a bit battery isolator switch to disconnect in event of short or fire.

[redfox355]

Originally Posted by MidnightMods

The 13.7volt charging might be a problem, I dont think I ever see my JK get that high and stay above that voltage, normally sits around 13.5volts

New dc-dc chargers can handle lower output alternators (they are usually an option offered by the charger manufacturer). They step up the voltage to get the charge into the battery, so you aren't just relying on the output voltage of the alternator to drive the juice.