Thats a lot of power... and hair hum... all the lights I could add with 200 amps

 

Okay so I'm new to the whole "add a second or third battery" thing. I have a moderate sized sound system that I would like to use to its full capability on the beach or even upgrade larger. Problem comes in that I've got a single battery that lasts only like an hour with everything running. I'm looking at adding 1-2 batteries under the toolbox (would build a box around them) to run the sound system without leaving me potentially stranded. What would I need to accomplish this? I've looked many places and seen battery isolators, battery connectors, and now run throughs. I need some aux batteries so any help is appreciated.

 

FWIW I think the reason the late model trucks have large alternators is the electric power steering. I have no idea how much power it uses but I'll bet the fuse is huge.

 

High current isolators (diodes) are expensive. I would do this:


Contactors are $40 on ebay.
This way, when the truck is on, you are charging your aux. batteries. When the truck is off- the aux batteries can die and your main battery is left alone.
I would get some good deep-cycle batteries to do this, if you deep cycle a regular car battery it will just kill the battery.

 

Hmm.. on second thought- maybe that isn't such a great idea to use huge wire and gigantic fuses. There would be basically up to 300A going straight into the aux. battery bank (without some sort of current limiting element). It could explode.
It would be safe to use smaller gauge wire (4-8 AWG), a smaller fuse (~50A), and allow the aux batteries to charge slower.