I have this super brain959 and also a duratrax ice and a duratrax piranha and a super brain 977 and the 959 never over heats a battery and you can set the peak voltage to what you want so it will never over charge only if you set the MV setting really high...and that would be from your fault.

Also MRC has it's own patented micropeak tecnology it's supposed to be better than zero delta peak.

heres my radio shack battery are you sure you got the one with the GP cells?
mine is just a hair longer than the stock tank 2000 batery it's almost the same exact size?