By The Way JZE.... I must say I like your Avatar.. I guess you are a resistor (Cause in that diagram that's the part that gets hot.
By the way did you know electric space heaters are a very rare device, They are 100% efficient. . Why is this? Well first.. that is what your Avatar is, an electric battery operated space heater,, but more importantly.. IN an electrical system, all losses are expressed as HEAT, and since HEAT is the desired product, thus losses are recovered.