I bought a 48V 20Ah Unit Pack Power triangle battery for my 500W Bafang geared rear hub conversion. No complaints, and I added a note when I bought it requesting the correct connector for my controller. They included an adapter, so no soldering. They don't use the best name brand cells however, so longevity is an unknown. They state that they use "powerful Chinese cells", which I found slightly comical. I get ~50 mile range if I pedal and keep speed below 20 mph except on downhills. YMMV