ashly95, I'm afraid you have been missinformed as to reverse charging due to to deep a dischargc resulting in heat, it just doesn't happen. It may ruin the battery by decreasing its ability to be recharged, but no heat. It also does not hurt a NiCad to be completely discharged to zero volts, in fact that is how individual cells can be tested for possible internal shorts; you discharge it to zero thru some resistance to limit current then remove the load. If the voltage immediately rebounds (open circuit) to .9 volts or greater, the cell is good. You do not want to reverse charge it though as that may ruin it. That is the reason for many saying to not discharge below 0.9 volts per cell. The keeps the possibility of the better cells reverse charging the weakest cell in the link near the end of the discharge cycle. As long as you never let the cell reverse charge, no harm is done discharging to near zero volts.