You have to watch the NiMh packs, They are eaiser to overcharge than the NiCad are. The last batch of NiMh batteries I got warned about leaving them on a trickle charge as they will continue to take a charge and start overheating. I'm not sure about your charger, but you want one that is peak detecting and as soon as reaches the full charge, take the battery off. Also don't "peak" the battery per the instructions with my charger. They tell you to charge it, and then after it goes to trickle, hit the charge button again to "peak" it. I blew one pack apart trying that, and got a second so hot I couldn't hold it.

I've finally decided that a cheap charger usually turns out not to be so cheap after all when you consider battery damage and in some cases loss of your plane.

Don

PS, your charger is a Peak Detecting charger so the trickle charge is what did you in.