Motor melt down...

[Panic]

Hello guys,

Could someone tell me how can i solve the problem as my title says?

I m running a reedy kr 12x1 motor in my lazer zxr with mrt pro esc and nosram 3700 mah cells + 4200 ib cells . All the soldering iron which holds brushes, capacitors and wires on the motor after 2-3 minutes of running is melting. The strange part to me is that it is happening everytime i use the intellect cells . Motor was recently skimmed and fresh lay down brushes were installed, I dropped from 19t pinion to 16t but problem continued . For some reason though all previous mentioned is not happening when i m using my 3700 mah Nosram cells and i m able to empty a whole pack without a scratch. Is it possible that batteries might be the problem???If yes how can i fix it ?.?

Any advise will be highly apreciated,

Thanks