Mounting the BAFANG battery was a bit tricky. The battery is designed for mounting on the down tube using the water bottle cage mount. However, my 48V 17.5Ah Jumbo Shark Pack Battery is so large that I would have to give up both water bottle cages.
Instead, I mounted the battery on a rear rack. Although they make rear racks especially for e-bike batteries, my battery is so large that I couldn’t find an e-bike specific rack the battery would fit on. As a result, I had to repurpose an old touring rack for the job and make my own mounts for the battery.
While I like the battery on the rear rack there are two drawbacks to carrying the battery on a rear rack. First, it puts the battery weight (approx. 9 lbs.) high on the bike. And second, it places the weight directly over the rear axle. Ideally you want the weight lower and centered with a more even weight distribution on the bike for better handling. Nevertheless, carrying a battery on a rack is not uncommon and I will ride it this way for a while to see how I like it.