Thread: second battery under the drivers seat - has anyone done this?

Optima batteries can be mounted laying on their side, would there be enough space by doing that. I’m sure there will be something that fits without having to do mods to the body.

Originally Posted by rijidij

Optima batteries can be mounted laying on their side, would there be enough space by doing that. I’m sure there will be something that fits without having to do mods to the body.

Yes, not keen on having the battery on its side, but you comment made me think if a lid modification would be an option.

Probably not unless you ditch the metal lid for the seat box. And even then, you'd be lucky to gain 30mm before you hit the underside of the seat.
The optima is a gel cell, so no liquid sloshing around inside like typical lead acid batteries. On their side is perfectly OK. A few mates with rock crawlers have them mounted in all sorts of orientations in between barwork etc. It's a non-issue.

There are a large number of battery size formats (group sizes), so you can choose one to fit the space, but might take a concession on AH rating, CCA or some of the other performance metrics of the battery. So your buying decision may be dictated on what application yo want your battery to meet.

As far as wiring goes... you'll have no issue running some leads thru the tin metal, over the TY case, and into the primary battery compartment.

Originally Posted by Toxic_Avenger

Probably not unless you ditch the metal lid for the seat box. And even then, you'd be lucky to gain 30mm before you hit the underside of the seat.
The optima is a gel cell, so no liquid sloshing around inside like typical lead acid batteries. On their side is perfectly OK. A few mates with rock crawlers have them mounted in all sorts of orientations in between barwork etc. It's a non-issue.

There are a large number of battery size formats (group sizes), so you can choose one to fit the space, but might take a concession on AH rating, CCA or some of the other performance metrics of the battery. So your buying decision may be dictated on what application yo want your battery to meet.

As far as wiring goes... you'll have no issue running some leads thru the tin metal, over the TY case, and into the primary battery compartment.

I hear what you are saying. Unfortunately, my marine Optima is almost brand new. So, I'd like to keep it. Also, I always used aux batteries that were capable of being used as starter batteries as well as powering my compressor, winch and fridge.

With the last 2 Counties & now my Defender I have removed the whole seatbox ( usually when I soundproof them) and turned it upside down, angle grinded off the existing base where it tapers down & extended the base about 100mm with steel sheet welded on. It then sits level with the chassis bottom rail. It sounds a lot more work than it actually is, this gives ample room for 2 x 100 amp batteries and storage above them. I can post pics of the finished result if you are interested.
David

Originally Posted by DeeJay

With the last 2 Counties & now my Defender I have removed the whole seatbox ( usually when I soundproof them) and turned it upside down, angle grinded off the existing base where it tapers down & extended the base about 100mm with steel sheet welded on. It then sits level with the chassis bottom rail. It sounds a lot more work than it actually is, this gives ample room for 2 x 100 amp batteries and storage above them. I can post pics of the finished result if you are interested.
David

Hi DeeJay.
Pics would be great if you don't mind.

Just make sure it can vent outside the vehicle if it boils. Even supposedly sealed batteries can vent if they boil. You don't want to fill the cabin with toxic fumes. Defenders have a vent for the battery under the front passenger seat.

Originally Posted by jbe

Hi DeeJay.
Pics would be great if you don't mind.

OK, Hope you can make sense. The compressor is basically sitting over the chassis rail if that helps orientation. Spares & tyre repair aerosols are towards the rear, next to the full river battery. Bit of spaghetti like but has worked fine for 6 years, although I did wreck a century battery but it was a warranty job. Basically I use a marine 3 way switch with the isolator at bottom right for a 3rd battery under driver side ( also enlarged) I have done serious 4wds stuff with no clearance issues.