I have a QFZ 36v 15ah battery that is almost 3 years old. Same looking for whatever that is worth (maybe nothing). FWIW no problems and great performance from mine over many recharges and many miles of use on a couple different bikes. I'm interested to hear if anyone else has experience with QFZ as well.
What bike do you have that uses 24v battery? Years ago my wife had a IZIP 24v ebike with the side saddle rear wheel chain drive motor.