Cleaning up and upgrading the batteries for a friend's Tidalforce S-750X

Rick dropped by over the weekend to have his S-750X upgraded from the dead front hub battery to the 16 or 20 Ah battery. He had it in storage for a while so it was a bit grungy. I've got quite a bit of work to do on it. Building the 36V pack, installing the Topeak rear rack and bag, installing the Cycle Analyst...