Wiring car sound system to a SECOND battery

>>1180510
just body ground it

>>1180511
Care to elaborate? I'm full retard when it comes to this shit.

>>1180510
You bolt the negative to the chassis of the car. Moat of the cars electricity flows through the chassis. Look at the existing battery's negative terminal. It is bolted to the chassis.

>>1180518
Ground it to the body. Doesn't matter where, as long as it is metal.

>>1180523
>>1180525
The sub has a ground cable that is currently connected to the chassis, so if I connect the negative terminal from the battery to the chassis in the same way, that should work?
That being said, the positive terminal is currently only running to the sound system, will that also need to go to the chassis?

>>1180510
How are you going to keep this battery charged up if it is not connected to your alternator? Do you plan on pulling it out and sticking it on a maintenance charger every night or something?

>>1180543
Essentially yeah, which is why it's been impossible to find guides on this lmao.

What you're looking at is exactly the same as the main speaker system in my car, which goes like this:

Body ground -> battery negative -> battery positive -> fuse -> speaker system -> body ground.

To answer your positive terminal question: positive battery terminal is connected to the positive on the speaker system with the fuse in between, everything else is grounded.

Just replicate that system with your second battery and you're golden. The only difference here is that you're going to not have this second battery also hooked to the alternator so you will need to recharge it using your charger. The fact that you have two electrical systems in your car running through the chassis will NOT cause problems UNLESS you short them out, which could destroy your car's sensitive electronics.

Quick question, why are you doing this? Do you sit for long periods of time in your car with music but without the car running? It might be easier to just let your main battery die and then jump it with a portable battery when it dies, although either this option or yours will kill the battery pretty quickly after a few 100% to 0% to 100% cycles if this is a daily thing.

>>1180545
have you considered something less retarded, like upgrading (more ah) existing battery?

>>1180591
Thanks for that, this makes sense to me.
I've had issues with my main electricals in the past, so i've decided to separate this system. I'd much prefer having a secondary battery for the sound system die while the car is idle, then have to jumpstart the main battery, especially with the state of my alternator lol.
How quickly do you think the battery will last? It's just one scrapped from a totaled pulsar, nothing special.
>>1180604
I've got the biggest battery possible in the engine bay currently and having everything hooked upto it still drains it quicker than i'd like.
inb4 put a truck battery in the trunk.

>>1180527
Yes, ground cables can use tge same mounting points.

Positive and Negative can never touch. That's how fires start.

What is the wattage of the amplifier if it's anything less than a competition setup you can just use a capacitor (1farad for every 500 watts) in line with the positive going to the amp it will take the strain off the main battery and you won't have to deal with all the charging the second battery fuckery

There's no reason you can't just attach the two batteries together via a (fused) line to their positive terminals and share a common (body) ground. Wiring them in parallel will cause them to balance each other, and your vehicle's charging system will keep them both topped up.

However, it will be more strain on your alternator when both batteries are drained by your need to make pointless thumping noises.

Consistent high loads from the vehicle's charging system trying to fill a sulphated battery is a common cause of alternator failure. Both batteries should be in decent shape.

File: dual_battery_system[1].jpg (35KB, 780x536px) Image search: [Google]

35KB, 780x536px

>>1180870
>There's no reason
Theres a few, actually.
IF you gonna go dual, throw in an isolator - could be as simple as a switch that will let you select which battery you using, but, a proper one will switch electronically, depending on voltage sensed. Assuming you mounting it in the boot, you also need heavy duty cable wiring, fuses, etc. - at which point, you may as well just swap for a single heavy-duty boot mounted battery anyway, but, just throwing in another non-alternator circuit connected battery, one you need to charge seperately? - this is 'Hell, No!' retarded. As are 3000W worth of car amps and shit, but, whatever.

>>1180883
An isolator is nice, but not necessary. It would prevent the stereo from depleting the vehicle's main battery, but it would also prevent the second battery from stabilizing voltage drop from the amplifier.

Get a god damn capacitor you fuck wit


GOD DAMNIT OP YOU MAKE ME SO FUCKING ANGRY

>>1180527
>the positive terminal is currently only running to the sound system, will that also need to go to the chassis?
Yes
Otherwise you'll get far to much faraday resonance.

>>1180527
https://www.youtube.com/watch?v=wmin5WkOuPw
on the stereo, loud, first, using the first battery. Then, connect everything on the second battery to your chassis and connect + & - with a brass bar at the terminals. Just to make sure. Then, jump in driver seat, and tear off down the highway in a blaze of glory. Otherwise, nope, do not connect live to chassis, ever.