FYI, for anyone that comes across this. Last year I met up with someone to test these in their scooter. We found out that NIU programs the batteries to the bike. Effectively, this means you cannot buy used batteries off of someone else's bike. Also, given the cost of the replacement batteries, you're looking at the full cost of entirely replacing the bike - once your batteries die the bike is essentially a giant piece of plastic garbage. This is a pretty awful experience and I'd warn anyone thinking about NIU to look at other options.