Battery?

I have electronics in my car that drain the battery. I want to add a marine battery in the trunk seperate from my car wiring, just to power the stereo and what not. I would just charge this marine battery with a charger every couple days. Has anyone heard of this, and know if this would work or not? I just want to be able to run the electronics without having to worry about killing my battery. This way even if i kill the marine battery, I will still have the main battery to power the car. Anyone? Thanks.

You wouldnt be able to go but MAYBE a day.

Look into getting a Cap, it will take the strain off your battery. Even with a LOT of electronics, you still shouldnt be doing that much damage to your car, you might need to replace the battery with something a little better such as an Optima Yellow Top.

What exactly does a cap do? Would that keep the electronics from killing my battery. And say I could go a day with that marine battery setup. That would work though right? Your just sayin it might not last too long? Thanks for the help.

I just had a friend figure this out for me (electrical engineer major) a 720 amp battery, with 120amp-hours, will power a 1600watt amp at full power for only 54 minutes. And thats draining the battery down to 0 volts, an electronic device (12v) probably wont function under 10.

A capacitor is almost like a battery, it saves up power for when the amp needs it. Like if your subs hit a really loud, deep note, that would take more power, so the cap helps lessen the sudden power draw from the car by supply the power the cap has saved for such an occasion.

exactly.

I have electronics in my car that drain the battery.

when does your battery drain? when the car is running? when the car is off but you're playing the stereo?

if the car battery is dying when the car is running/being driven, then you most likely have a problem with your electrical system in the car- either a (going) bad alternator, or a bad battery; a bad ground or power connection could cause the same symptoms.

if everything looks okay on your electrical system, you are probably drawing much more then your alternator can put out. my suggestion is to turn off that silly-ass 15" sub in your back seat and build a system that sounds good and draws less :grinno: if you are drawing that much, then you can install a larger alternator in your car, along with something like an Optima battery. this should hopefully alleviate any problems you have with your battery draining.

as far as a dual battery setup goes, the only long-term viable option you have is to tie the second battery into the main electrical system. run very heavy gauge wire from the power side of the second battery, and ground the second battery to the frame. put a heavy switch or relay between the two, so you can isolate your battery in the trunk from the one in the engine bay.
when you hook up your stereo/amplifier/etc..., tie your distrobution block into the battery in the back. this way, if you want to isolate it, flip your switch, and all your auxilary electronics will be run from the battery in the back. flip it again, and it's tied into the main system.
if you feel really energetic, you can build a circuit that moniters system voltage and automatically breaks the bridge between the two batteries if the current reaches a level where the car will not start- some cars have something like this for if you leave the headlights on.

i've used a system like this successfuly in large commercial tractors, and will have a system like this in my car. i'm installing a computer, and like you, i don't want to have to call AAA to get my car jumped because i left my wifi up :lol:

Think about leaving your lights on overnight, that kills the battery. Now imagine a powerful stereo and do the math.

but... but... i'm bad at math! you do it!