[ILLusion]

Dischargers work by converting the electrical energy in to another form of energy - typically as heat.

Depending on the discharge rate of your discharger, the heat will vary. Most "intelligent" chargers discharge at a rate of 4A with moderate heat. Some cheaper unmonitored ones could discharge at a much higher rate which will drain your battery quick, but will also become very hot. Another negative side effect is that discharging at such high rates is harmful to your battery pack.