General > General Technical Chat
Power supply power factor
raptor1956:
I just picked up the new DJI Mavic Air 2 drone and since I plan on charging my batteries in my car using an inverter I wanted to know what the power draw of it is. So, I plugged the little power brick for the drone charger into a Kill-A-Watt and saw that the charge power was around 36W, a bit less than I guessed, but the VA was over 70VA making the power factor pretty bad at not much more than 0.5. That seems really low, what might be the reason?
Brian
NiHaoMike:
Not much point having PFC for small loads. See what voltage the power adapter is and you might be able to find something like a laptop adapter for a more elegant solution than an inverter, or even power the charger from a larger battery out in the field.
themadhippy:
--- Quote ---but the VA was over 70VA making the power factor pretty bad at not much more than 0.5. That seems really low, what might be the reason?
--- End quote ---
more than likely there using a capacitor dropper instead of a more expensive transformer
srb1954:
A power factor of 0.5 is fairly typical for a simple power supply without power factor correction.
raptor1956:
I didn't expect the PF to be over 0.8 but I wouldn't have expected it to be under 0.6 either. Now, add in the losses with the inverter and to get, say, 40W out I'll need to source right at 100W or 8A -- within the range of the cars outlet.
Brian
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