Teenhulk want's to relocate his two batteries to the rear right for better weight distribution in his '82 Audi. The car came with a big ass stereo system from the PO with it's own battery.
Right now the battery isolator is in the front and a heavy wire runs to the trunk for the stereo AGM battery.
I think it's just one wire so I guess he has to run a 2nd heavy wire to the back for the alternator? do I put the isolator in the trunk?
Trying to get my head around how to wire this....

Present set-up: 1st pic is the isolator in the blower area, 2nd pic is what's in the trunk for the stereo battery.

The isolator pic top two smaller wires it says is the main battery, middle alternator and bottom wire is the stereo battery cable that runs to the rear trunk.

What does the isolater do? Just a relay to isolate the stereo system when the engine is off (to not kill the main battery)?

If existing Big Ass Wire to the back is sufficient gage for what the alternator can output, then I suggest putting the main battery in the back, connect Big Ass Wire to starter battery terminal, and then wire the isolater in back.

If Big Ass Wire not big enough for the alternator, run a new one and then the above.

Edit: oh, and you'll need to find a ignition-on power source to activate the isolater.

If he's already got a ton of stereo gear in the trunk the 40lb battery isn't gonna make much of a difference.

Tell him just to buy a lighter primary battery for the front, it'll probably be cheaper.

You are correct, you can run a 0 or 00 gauge cable from the rear to the front to handle the starter duties and create a Jump point in the engine bay. To make it simple you can just leave the isolator where it is and connect the alternator to the same terminal on the isolator from the main battery or make a secondary positive post if you chose.

Keep in mind that car audio wire is not as good as they advertise so welding cable is usually a better alternative

That circuit breaker is within 6" of the rear battery, correct?

There should be a second unit up front also in case the main front to rear cable gets shorted (say a t-bone accident)

This will apply to the main battery cable now as well.

Would a lighter battery like an odyssey 925 for a main battery in the stock area work ?

It would be a lot less hassle.

'82 Audi what? Neither the 4- or 5-banger really need a lot of amps to start. I used to start my 1.8L Acura Integra race car with a Braille AGM that was around 6"x6"x3".

Plus, depending on how the stereo battery is wired (or wired with a manual override switch, that optional battery could be used for any additional safety "get home" amp-hours load in case of alternator failure.

Audi '82 coupe 5 cylinder, 2.1 100hp 8.5:1CR.
But he's looking for an audi 5000S 2.3 10:1CR 130hp NF code engine, it supposed to be a bolt in and work with the stock CIS FI.

I don't think this isolator has a manual override switch, I only see 3 posts.

Not a bad car for a 17 year old.

What all is in the Stereo? I rolled in a minitruck back in the day with just an Optima redtop and a few caps.

Unless he's doing SPL competitions.... different needs.

Car came with it, installed by the PO. 16 speakers, EQ, and this is the trunk....

Wife wants another newer TT, wonder if I can talker her into one of these...

I love those 5cyl quattro...yay!

I love driving it, it's a car you enjoy driving, even with the 100hp it's still sporty. Getting into the back seat is a royal PITA, but once in there it has incredible room. Trunk is a bit small.




Talked to the lad, this is the winner, Thank you saves him or I should say me a lot of work.

Hardest challenge I face is to keep the lad from doing stupid ricer shit to the car. He wanted to put 17" rims on it, but 15" is about all the short tires and small wheel wells can handle, stock is 14". He also wanted to do later head lights, make the front audi badge black, rear wing, etc...

I negotiated to euro short bumpers, tint, future 15" rims and paint the rear quarter vents black.
I get it, he's 17, hard to get into his head that it's a classic and he should't mess too much with it.
But it his car, he paid for it by slinging donuts at Timmy's last summer.