So who relocated the battery to the trunk?
Reply #4 –
+1 to what BlackCardinal said.
These guys make a relocation kit to do what BlackCardinal suggested.
http://www.madelectrical.com/
I personally haven't dealt with them but they come recommended (for whatever that's worth)
Autozone carries "welding cable" that will work. The big hardware stores carry appropriately sized cable. Not sure which is cheaper.
Both of my birds have trunk-mounted batteries. I did one, the other came that way.
Since I've been digging around the trunk the last few weeks I've been looking at ways to maximize the trunk space. IF you want to get creative and are willing to spend (a lot) more money, it would be possible to mount two mini batteries over the wheel wells or in other out of the way places . I don't think a single mini-battery is going to be enough for our cars.
Optima makes a 3-core 6V battery. You could mount two of those in different places (eg outside the frame rails).
In any case where you have multiple batteries, you want to wire them a little differently than you would a single battery. A lot of diesel engines come with multiple batteries, you might check out how it's done.
For a std-sized battery, there are plenty of choices. If you look at Gumby's bird, he chose a pretty good place from a performance standpoint. Nestled up next to the rear seat, near the premium sound gizmo is out of the way, but you get a different flavor of weight distribution as compared to moving it nearer the bumper.
Some Mercedes Benz's have batteries mounted in wierd places - like under the passenger seat, and are really hard to access. So MB has some std. terminals conveniently located in case you need to jump the car. You might think about something like that when mounting yours if the battery is going to be out of the way and/or encased.