It seems like there may have been a bad batch of the 4s 4500's going around. I have two of them that each have a low cell.

One of them had a cell go almost to 0v. I did the nimh charger trick on that cell and it's been running OK ever since. That's a weak cell and it always discharges first. I set my cut off on my esc to like 3.4 and only run it for 8 min max in my buggy during practice. The battery does work but I'm waiting for it to burst into flames.

The other 4s 4500 battery I have was fine for about 10 charges and now it also has one cell that likes to go lower than the rest. I treat it the same as the above battery but I've never had to do any charger tricks to it. I also expect it to burst any day now.

With that said I had 1 2s2p 5200 hard case that I used for about 200 charges without a problem. It still works fine but doesn't have the punch like it used to.

I also had 3 2s1p 5000 25c soft case turnigy's that I used about 50-100 charges. Those batteries worked fine but eventually felt a little soft. I don't have them anymore but to my knowledge they still work.

I have 2 2s 6000 25c-50c- nanotech's that work great. I belive I have about 100+ charges on them and they're awesome. They're just starting to get soft now but they're totally fine.

I just recevied 2 Gens Ace 4s 4c hard case last night. They balanced flawlessly and performed perfectly. I'm really happy with them in the 1 charge I ran on them. However, my friend has 1 2s that had 1 cell die and 1 2s that the case cracked open. The 2nd battery is nothing a little glue won't take care of. I did see another Gens Ace 2s that had 1 cell die. When they tried to open it they punctured the cell and it went up in smoke. I think their good batteries if you don't mind fixing stuff. The cells are solid, just the soldering or something might need some work.