Hey guys, I just purchased 2 HPI Sprint 2 sports for my boys (6 and 8) for Christmas. I am getting out of nitro so I had 2 batteries left over from the bump box. I also purchased 2 Trinity Reference 6C 5000mAh Pack Tamiya batteries as well as my neighbor gave me 2 venom 3000 batteries. So i felt pretty covered on the battery end however last night as I was preparing the cars for the boys I tried each batter. I held each car up and gave throttle forward and reverse. Only 2 of the 6 batteries held power for more than 20 seconds. 4 of them would give a high beginning 3 seconds and then noticably come down as I held the throttle. Neither of my new batteries were the ones that were working well.

So my question is could I have done something to them during charge? My neighbor is in the hobby and he helped me charge these.... some of the charges are going up to 8.2 and one even to 9 before saying charge complete.

Any ideas? Those new batteries were $44 per and I wouldn't even get 45 seconds out of a run with either of them. That would've been a disappointing christmas If I hadn't checked them.

When you charged them did they get hot? NiMh peaks at 120-130F and if they didn't make it to that kind of temp, they didn't get much of a charge due to something called a false peak. I asume your friend is using a peak type charger, that's the best for NiMh.

Voltage on a NiMh pack means little since the cells recover voltage pretty quickly, its when you put a load on them like you did in teh car that lest you know whats there.

NiMh packs can wind up sitting on a store shelf for a long time and the batts self discharge so there's nothing there. They can be brought back by cycling - repeated discharge/charge cycles if they're not so old that they're compromised.

I called him last night and told him my problem before posting here. He said that he'd grab the batteries from me today and try cycling them today.... so I think he's on it! Thanks for the info.

That should wake them up, sounds like he knows what he's doing.