electric bikes?

Anyone rock an E-bike? I was just offered one for free from a customer. I only saw the 20" front rim peeking out from under a tarp,, I thought it was an old moped. IT had a drum brake so I think it's an older commuter style, Not the cool modern style cruiser adaptation. Very lucky on my part as my high schooler was just asking g about making a hub motor E-bike out of his old cruiser...they guy said it was broken.." only had a 10 mile range". Well I can fix that with new batteries. Do lipo batteries retrofit to older GMA lead acid battery systems if the voltage is the same? I won't be able to pick up until June 26 so I have no specs on it yet.