Pingbattery used to be a lot better. Some of his newer batteries have had some problems. Not sure why. The Thundersky's are better batteries in my opinion. People seem to be having a lot of trouble with the ping BMS's.

The thing is that a lot of those ebay batteries are factory rejects I think. I don't have proof but how are they providing these batteries for so cheap. I think pingbattery.com might be also using factory rejects but he probably is better on the inspection but lately, I think he's been letting some bad ones through.