OK, I bought one of theses batteries

https://www.alibaba.com/product-detail/Free-shipping-Unitpackpower-U009-hailong-super_1600645736732.html?spm=a2747.manage.0.0.31de71d2FHqTcV

However, in my excitement, I ordered the biggest size wanting more range, but didn?t think about the size.  So, bummer, it doesn't fit between the two down frames where the factory one fits.  I did test the battery and it plugs into the existing socket and the computer accurately reads the charge, so all good there.  I?m making a mounting plate and will mount the new battery on top of the top down frame.  I?ll send pics when it?s done.  Saved LOTS-O-MONEY and now have plenty of range for my Sunday rides.

I have another lithium ion battery charger from another e-bike manufacturer.  Same plug, same polarity, but rated at 54.6V and 3 amp as opposed to the Rad battery charger rated at 48V and 2 amps (labels on the chargers).  Does anybody know if the higher voltage and amperage charger will work without damaging my battery (RadWagon 4)?

While looking for a replacement battery for my RadWagon, I found a vendor that rebuilds e-bike batteries.  Does anybody have any experience with this kind of product?