I have a second battery I would like to install in the trunk to power my system but was wondering how to hook it up to the front battery

 

here you go! also notice this pic includes THE BIG 3 mod. also!

 

midnightracer: some people hook up all battery's parallel some use isolator's or relay's to separate the starting battery when the car's not running.


crazy ken kid: You've got MAD MSpaint skillz

I'll also be throwing a old red top agm gel cell into the trunk.. even though I don't have a sealed battery box yet there is a vent in my trunk, i was going to get the borg warner r3098 battery isolation relay 200 amp I'll first try a glow plug relay that I have off a diesel engine. i think the back battery will get less charging volts but there might be a way to convince the alt to bump up another half volt i'll look into that if the volts get to low.

 

ya i divided on using a relay(soleniod) setup b/c it is to much hassel and i have never had an issue with mixing and matching batteries yet (knocks on wood) i believe the idea is when you play your music with the car off and what not, when the car is off the soleniod breaks the connection so when you start to kill the back battery it doesn't kill the front (starting your car) battery also.

also when charging and your car is off the strong battery will pull from the weaker one to keep my fully charged!!

also here is how to set up an soleniod (relay)

 

If your placing a battery in the trunk be sure that it is sealed and non-spillable. Many starting batteries release gases that you don't want to be near.

Other than that, just wire it in parallel like Ken has outlined. Big three is a must.

 

ya i forgot to point out always hook 12v batteries in parallel. the only time when i see batteries hooked up in series is when ppl have 6v batteries and want a 18v setup! lol! but for that you will need other special equipment lol!

 

I'll wire the solenoid either way not sure the condition of either battery ... the one in there is great, the one going in should be great but it would be good to have them disco'd I think. it would be good to see if the light's dim without it and then if they dim with it hooked up. I'll also be removing the 1farad stinger cap with digi gauge.

 

I might keep the cap just to use as voltage meter, this would be a better way to evaluate your charging system than your headlights. You could even use it to measure the resting voltage of each battery before you connect them.

 

I have multimeters around plus I'll prolly have to use a bunch of the spade connector's I used to hook up all the amps to the cap to get the other batt wired

 

keep the cap! it is helps to smooth out ripples and nice volt meter also!

Battery or Cap - SSA Car Audio Forum - Page 2