urban- i ordered a battery kit (Taylor) that came with 2 gauge power wire. after driving around for about a week, my stock battery dosent have enough juice to reach all the way to the front. what do you suggest i do? my buddy's at the warehouse told me to just go ahead and order an optima battery. one of the techs at mitsu said the stock battery is crap if your going to do that kind of stuff. any input?

 

I believe the M3 also has a trunk mounted battery for the record. Weight distribution is generally the primary issue when relocating to the trunk. It removes from weight from in front of the front axle and puts it behind the rear axle, thus counterbalancing some of the weigh from the engine. Also it's usually put on the passenger side to make up for the weight of the driver as Brian mentioned.

I had mine in the trunk for 6 mos before I blew a piston, and it's going right back in now. And similar to what was mentioned on the first page, my intake filter from my turbo side right behind the passenger side headlight, which is easily removable for track events if I wish to take it out.

 

I don't think it would fit in the spare tire well, but you could possibly do that if you removed the tire and used a smaller battery (not recommended unless you only use the car for racing). BUT, it is a good idea to put it on the passenger side to counteract the driver's weight. That's where I have mine, on the right side just behind the wheel well.

.L. I have the stock battery in mine still and after about 10,000 miles it's running just fine. I think my kit used 0 guage wire and I do not run any extra electronics (no fog lamps, amps, subs, etc.) if that helps. But Optima batteries are pretty good.

 

I just did my battery relocation and i used 1 gauge wire. Your problem might be that the wire is too thin so your getting a bit of a voltage drop and the charge from your alternator isn't getting to the battery.
I say you should grab an optima yellow-top battery because i heard that the fumes from the stock battery are toxic. The stock batt is not a sealed battery so it gives off fumes plus it can spill and leave a nasty mess in your trunk!

 

great, thanks for all the info guys. the tech at mitsu told me that the stock battery has very low cranking amps. basically just enough juice to get your car started. he said its very possible that the stock battery drains after a while being in the trunk and having to "work" its way up to the front. like i said before, maybe its because i have 2 gauge wiring.... so it needs to work a little more. i'm going to buy a yellow-top battery and see how it goes. thanks again.

 

While you brought the subject up, did he say how many CCA (cold crank amps) the stock battery has? My next battery will be a lightweight one, but I don't know how many CCA I need to keep reliable starts.

 

^you know i honestly forgot how many he said. somewhere in the realm of 70-80ish. well at least i think thats what he said. i dont even remember the CCA of the optima yellow top, but i think its around 150-160ish. i'm probably wrong though. but those numbers do sound familiar.