I was a N.E.W. dealer back in the day and remember having to fix a few of the battery boxes. If you open up the big black battery box, you will see several smaller batteries in there. I'm pretty sure that they were just regular motorcycle batteries or lead acid or? I think we were able to find them pretty easily. You should be able to google the part number that's on them to find some. Of course, this was many years ago and I could just be crazy...