super overheated batteries

[kyosho501x]

well i left my radio charging and went out for dinner then went to the mall. when i came back, my radio was melting, no kidding literaly it was melting. i forgot to unplug the wall charger, but it was supposed to stop charging. well i got the batteies out and tested the voltage and they were all above 1.2v. my question is can they still be used again?

here's the damage



some of the heatshrink came off of the AA batts

[Takedown]

1.2v per cell is nominal... My guess is that their is a bad cell or their is a short in your pack.

[BL-Power]

What loading current did you use?

[BrianG]

Those run of the mill cells don't like 1C charge rate from my experience. They heat up too fast and/or false peak when doing so. It seems they like a slower charge, so I usually charge at around 0.5C for a couple hours and they seem to like that a lot better. Also, I set the delta peak as low as possible (3mv/cell) - they just aren't as robust as normal R/C NiMHs.

Not that it is recommended, but if you must charge unattended, use the temp probe and set the temp shutoff value for something like 100*F. That way, if they aren't peaking right (from a possible bad cell), the charger will still shut off before you get melted parts.