Yes, I tan them. But ewww?? I haven't heard of using battery acid. I got my initial supplies from Fur Harvesters Trading Post:
http://www.fntpost.com/Categories/Fur+Handling/Tanning/Tanning+Kits+Supplies/
Even if you don't order from them, the site gives you an idea of what is out there. All my rabbit pelts are rolled up in the freezer right now. But I have tanned squirrel, racoon and deer. Oh, and one copperhead skin I turned into a hat band. There is a way you can use egg yolks, have not tried it yet. Not adventurous enough yet to try the brain tanning.