Join Date: Nov 2011
Location: Glastonbury, CT
Just sit right back and you'll hear a tale, a tale of a fateful first battery purchased off eBay, that started from these very boards. Take from it what you will, and make your own decision:
Seller advertised a 36v 10Ah LiFeP04 battery kit for a remarkably good price. I ordered. It arrived from Canada quickly. So far, so good. I did notice the packing material inside the box was newspaper over 3 years old, but, meh, packing materials don't necessarily equate to manufacture date.
Over the course of the next month, I built up the bike and took it for a test ride. According to my calculations, I should have gotten about 24 miles out of the battery on the 250W front hub motor set up I built. I barely got 12 before the battery cut out. This happened several times. I decided to take the battery apart and test the individual cells. The cells tested all over the place: from 3.97 volts to 4.23 volts, and every reading between. Several of the connectors between the cells were cracked, the wires connecting the cells to the balancer looked to have been soldered by blind drunken monkeys, and the internal date stamped on the battery showed it was indeed over 3 years old.
The best part, though, was the battery was clearly LiMnO2, not LiFePO4. Oh, wait, no, the best part was by the time I figured this out, 2 months down the road, the seller was long gone, no longer registered on eBay, and PayPal's response was "sucks for you, doesn't it?"
So this is the tale of a cheap castaway eBay battery. IIWY, I'd save myself time and aggravation and buy a quality battery from a reputable dealer who stands behind his/her products. Grin, Ping, BMS - they're all mentioned on this forum and on Endless-Sphere over and over again for good cause.
To finish my tale and be quit with it: I ended up spending an additional $250-ish and bought 4 x 24v 5Ah LiPos from HK to make a 48v 10Ah pack. With a quality charger from Progressive, it makes a nice set up with which I'm very satisfied. It was, however, an expensive lesson to learn.