Replacing lead in a Chinese scooter bike

These little bikes are everywhere in China, they are made by the millions, and they have lead acid batteries.  This one had a set of four 12 volt, 12 amp hour units to make a 48 volt pack. The bike looks to be basically brand new.

The large plastic battery box almost fit a 48 V 20 ah pack made from Sony 18650 V3 cells that I had on hand.  Almost of course would not work.  After removal of the plastic box, the space in the frame was a good size, and fit the pack nicely, but these naked packs need to be protected from rain and physical damage.

I took the battery to Adrian at Islander Sheet Metal and he was able to fabricate a very neat box from galvanized steel sheet.  I painted it, then  bolted the box on using the original mounting locations. A little packing foam protects the bottom and top of the new pack, and I changed over the power connectors to 30 amp Anderson Power Poles, to match the pack. The bike is now better than new, with a healthy range of about 50-60 kilometers.

The leads on the battery were bought out of the box through keyhole slots that I cut in the top rear lip of the box, and protected from the sheet metal with rubber grommets.