Quote:
Originally Posted by Marvin
Ok.
I am charging a 7.4V 5000mAh battery at 5A.
The Voltage supplied by the charger is 8.4V, and the current supplied is 5A (assuming that for the one hour charge, the current level remains the same, even though it doesn't). 8.4 x 5 = 42W.
Most chargers are about 80% efficient so 42 / 0.8 = 52.5W drawn from the power supply. The power supply provides this power at 13.8V, so 52.5 / 13.8V = 3.8A.
However, the power supply is also not 100% efficient, more like 75%, so 52.5W / 0.75 = 70W.
70W is drawn from the mains. 70W/230V = 0.304A.
70W are drawn from the mains in that hour, so 0.07kW. Which, assuming electricity costs 5p per kWh, is 0.35p. So not too much really.
|
it costs me, squeek, bubble, the monk, matty,t speed turner and who ever else scabs a supply off the genny a fiver a day
between us all