adreano17

what will i need to successfully do this? i already have a deka 9a31 under the hood, plan to get a deka 9a31 for the trunk. what will i need to successfully do this? i know i need to have an inline fuse, but what would be a sufficient fuse? to pull an amp draw from the back.....and do i need a battery isolator or anything like that? please help. thanks.

adreano17

Probably should have put this in electrical. My fault.

Pyroibw

all you need to do is run power cable from the front battery to the back battery, thats it . isolators are useless unless you plan on playing your system for long periods of time with the engine off. no need for a fuse between batteries, just before the amp.

Walnut

Depends if you don't mind having a massive electrical fire if you get in an accident then sure skip the fuse. And if you don't mind not being able to start your car cuz you pumped music at the beach for 3 hours then you can skip the isolator.

Walnut

That battery is going to gas into your trunk. So if you don't mind toxic and corrosive gas in your trunk...

adreano17

i was going to use a fuse regardless. i know enough about electrical for that lol. and it would be a AGM battery. 100%safe and dry =)

Walnut

Ok, sorry I wasn't familiar with AGM technology. Looks like a step better than gel. For either type I would recommend a Schottky isolator to reduce the charging voltage to the aux battery, unless maybe there is a 0.2-0.3 V drop in the cable to the trunk, could well be.

KLF

Tons of cars come from the factory with the battery in the trunk. Most BMWs are like this, the Mini Cooper, etc. Hell, my old VW had the battery under the driver's seat. That was... I think a '75?

Walnut

There is a big difference between an engineered installation and a DIY. There can also be varying qualities of engineering. A battery under a driver's seat would just be bad engineering. Or if you don't mind breathing acid and strontium fumes go right ahead

Walnut

To answer the fuse question...you need to start with a design...which is based on your design goals. There's two basic options. 1) Use an isolator and a small cable which is going to carry charging current only, in which case you can use small fuses. 2) No isolator, big cable, big fuses. Note that you need fuses on both ends of the interconnect cable.

KLF

Some BMWs have the battery under the back seat. I would think by now they would know a few things about quality engineering.

Walnut

I would trust BMW engineers to properly contain and vent a battery under a rear seat. Doing this properly under a driver's seat, dubious.

Walnut

Pyro is Latin for fire