Reply to thread

Watts = Volts * Amps

If the input is 6V and 3A is flowing, the power is 18W

If the output is 4.2V and 0.5A, the power is 2.1W

The difference is coming out as heat due to inefficiency and is the difference = 15.9W

Actually how hot it gets depends on how well it can dissipate the heat, typically through a heat sink and maybe forced air cooling from a fan. You need to know the C/Watt rating of the device and heat sink to calculate that.

Brian.