Charger in the charging time is a bit hot is normal, as long as there is no smell do not care about it, but the best place in the ventilation, because the heat will accelerate the aging of electronic components.
So there is basically no PFC circuit, so the power factor is only less than 0.7, the rest of the energy is basically converted into heat.
This is unavoidable, AC and DC in the conversion of the existence of loss, the general use of more efficient charger charger switching power supply, but limited by the volume.
