Ok so I am using the standard NiMH battery that came with my recently purchased slash 4x4 and I can see that it is becoming increasingly hot after driving. I can tell that it is beginning to melt and want to stop it to avoid purchasing a new one and doing the same thing. I typically drive it on road, and through grass a couple of times. I also drain the batteries before recharging. Also, when should I throw it in the trash and buy a new one? How bad does it have to get?