I collect vintage non-digital camera gear, which means on occasion I find an old battery still inside. Usually, if the corrosion isn't too bad, I can clean the

I collect vintage non-digital camera gear, which means on occasion I find an old battery still inside. Usually, if the corrosion isn't too bad, I can clean the piece up and replace the battery with a standard 9v or AA battery, because those things haven't really changed for a long time. Once or twice I've had to make a little patch with a bit of tin foil. I'd hate to be completely dependent on something I couldn't fix.