I removed the factory battery, and went with a car battery under the seat for two main reasons. First I live in NH and it gets cold here in the winter and my 700 doesn't care for sitting in the unheated shed for a week sometimes then trying to start it. So I wanted the extra cold cranking amps to help here. Second reason is because while plowing last year with the heater being used intermittently, the stock battery/charging could not keep up.I only had to stop once for a few minutes to let it charge, but I have heat and I want to use it. I have a stereo that is wired (for now) to shut off with the key so I don't really have a need for any accessories to be used while its not running, so for me a second battery is not needed. Plus I like to keep things simple, a single battery with as few connections as possible so minimal chances of failure out on the trail.
sorry about the crappy pics, heres the under view
I put some tabs on three sides (the fourth side is right next to the plastic side panel) for some 1/8" aluminum sides for stick/heat shields.
I thought I had some pictures of the battery installed before I put the side back on but I guess I didn't. I can say that this upgrade is well worth. I haven't had any problems starting it in cold weather,in fact I find it starts a lot easier this year and for the few times I have plowed with it this year it seems to not run the battery down that much with the tunes blaring and heater on.