Battery relocation, some questions

[Scott]

Hi all,

I have never liked the location of the battery in elderly saabs, and periodically think I'd like to move it.

Have any of you relocated the battery on a car that is primarily street driven? The back seat makes sense on a rally car, but not on a street car. Where in the trunk is the best place?

How is the battery secured? Does it need to be vented?

How do you run the new cables through the car?

Sorry for all the questions, thanks.

[Geoff]

I did one on my daily driver '85 SPG. I put it in the trunk on the passenger side just behind the seat. At first I had it mounted on a regular generic battery tray but later went with a marine battery box. I didn't vent it but probably should have. I think you can use an Optima battery, which are sealed, and then you don't need to vent it.

Welding cable is a good source for battery cables. I ran mine between the trunk floor and rear seat, under the rear seat, along the passenger side carpet, and up through the big grommet in the firewall/side near the ECU.

There was someone I met who put a small battery under the rear seat. It was years ago and the battery was pretty expensive at the time but prices have come down. Check out dry cell batteries such as Odyssey. You may find something that can fit under the seat.

[SwedeSport]

I mounted a standard size battery to a frame I welded to the rear seat crossmember. I then secured a Summit plastic battery box to the frame. There is a vent that goes out thru the floor, and it's included in the kit. The box is big, and is exposed with no rear seat, and would not fit under the seat.

You can probably use the same setup in the trunkwell too, and keep your rear seating and interior intact. If you don't mind looking at it when the hatch is open, mount it right behind the seat, or you could put it in the trunk well where the spare and jack are hidden, but with a full size battery, you will have to cut the wood floor to fit it.

I like Geoff's idea of using the smaller dry cell battery, but your project cost goes up a bit.

Just make sure you use heavy enough wire. I run a 1 gauge ground from the battery to the frame, and 4 gauge wire to the front. If I were to do it again, I would probably go up to 2 gauge up to the front. Plus you are going a bit further, so heavier wire is a must.

There are some pics in my thread, viewtopic.php?f=18&t=1540&start=75

[hutch]

I have the same setup as Geoff in my 86 and to be honest for a DD ita a bit of a pain. You can still fit a large volume of items, SwedeSport can attest we fit nearly an entire c900 interior in the back of the car, but big things like desks, mattresses etc have trouble because the battery tray takes up an annoying amount of space. Not bad at all for a race car but it can be a pain for a daily, since that is typically something the c900 does so well.

If you're willing to replace the stock intercooler with a front mounted unit you can easily move the battery to where the stock airbox is and probably even keep the stock wires. I replaced them for good measure but if I were to do it again I'd probably not bother with it.

[DrewP]

A group 58 battery will fit in the right side trunk floor, under the floor panel and still let the spare tire trap door close flat. That's what I have in my cars. I just made sheet metal brackets to wrap up and around, and just screwed through the floor with rubber washers to seal out moisture.

I ground the battery to the body in the trunk, and just run a positive cable up under the carpet right to the alternator & starter. Leave the positive and negative cables in place, as they ground the engine to the frame, and connect the +12 lugs on the starter and alternator to the +12 distribution block on the right side inner fender. Just wrap the original + terminal up in electric tape or heat shrink.

The only time I move mine is to make room for bigger downpipes, though the argument can easily be made that shifting ~40 lbs from the very front of the car to the very back can only do good things for handling in a 99 or 900.

[Scott]

Thanks all, lots of different approaches.

I forgot to mention, I'm referring to my 74 99. I kind of like Drew's idea, as it seems the least intrusive.

Its probably overkill in my situation, but cooking the battery, and rusting under the battery shelf concerns me.

[DrewP]

I think the compartment in the trunk floor in the 99 might be even a little deeper than the C900. I like it there because it's out of the way of cargo. You have to run the wire a little farther though. I think I usually buy ~25ft of wire and have a little left-over after for if you want to make a nicer cable to connect the starter to the alternator, or something like that.

[99Super]

I used an Audi battery cable from the local wrecker, pretty cheap and already has ends on it.
I used a Sears battery box behind the seat (99 Sedan) and it does take up a lot of room, but I had no choice as I was installing a turbo in an N?A car and had to have room for the downpipe.

I think I'll build a box for under the back seat for the SPG

[Scott]

Why the Audi cable?

[Crazyswede]

Why the Audi cable?

I am guessing because many Audi's have the battery in the trunk.

[99Super]

Why the Audi cable?

I am guessing because many Audi's have the battery in the trunk.

Correct. Cheap and easily available from most any junker.

[Scott]

I didn't know that, pretty cool.