Right now I am running a group 24 deep cycle 12V lead acid battery. Its rated for 80ish amp hours.
I agree, it'll be interesting to see how much it'll actually regen. I think I may pick up a 100a ammeter so I can see what is actually going on. I did some rough calculations that showed I could possibly regen roughly 2-3Ah per commute. My commute would use about 8Ah though (again guesses as I don't know my current draw).
The main reason I'm considering it is I have a few fair size hills on my commute. Both have stop signs/lights at the bottom. So, I have several opportunities to regen brake a bit.
I also just want to try it.
It sounds cool to have a normal car with regenerative braking.