I've never had a battery do this, and it is not only weird, it is scary.

I threw out the suspected bad cell, and just for grins soldered the pack back together as a four cell pack. I put it on my Accucycle Elite charger. It quickly rises in voltage, and peaks out over six volts and the charger turns itself off and makes the sound letting you know the pack is done and ready.

I then put it on "discharge", and you can watch the voltage rapidly drop, until it shuts off after having pulled out about 50 (fifty!) mah. I've done the process several times and it does the same thing each time. Each cell checks out within .02 volts of the others.

This really scares me, because since the charger seems to charge the pack normally, one could easily assume that the battery was charged, ok, and ready to go. And then go lose a plane just as I almost did.

Any battery experts here in this group care to comment? I've got a good number of planes, and now I'm "battery scared." Yeah, I know, battery backers, etc. But I want to know more about the "hows and whys" of this pack going wacko, and how one might predict and/or prevent it.
Thanks,
AV8TOR