New 18650 Charger not working, how to test?

I just received some protected 18650 cells and a charger. I hooked the charger up through a Kill-a-Watt meter, but it's pulling 0 watts and 0.01amps from the outlet. This charger is supposed to charge at 1A per channel (2 channels). How can I monitor with my multimeter while it's charging the cell? What setting to use on the meter?

Hello Superorb,

It looks like your charger is drawing 0.0012 kilowatts. Working backward to 4.2 volts, I believe that works out to a charging current in the 3 mA range.

If you connect your volt meter to the + and - terminals of the battery you should be able to monitor the charging process. The cell will read 4.2 volts when at about 85% full charge, all the way to 100% full charged. It usually takes 45 - 60 minutes to go from first reaching 4.2 volts to a full charge.

Tom

Thanks Tom. Since the input is 500mA max, shouldn't it be pulling more from the wall than 0.01 amps? I had the meter on it while charging and the volts looked correct, is there a way to measure charging current in mA with the multi meter vs. the wall meter?

P=EI; I=P (1.2W) / E (4.2V) = 0.286A or a bit under 300 mA. A 300 mA charging current at 4.2V only needs to draw 10 mA from the 120VAC. This doesn't take into account efficiency, but unless you have a very accurate meter, the 0.01A wall measurement is probably only approximate. The suggested 1 amp into the battery also may depend on the state of charge; the charger may be throttling back a bit if you put a cell into it which already had a good state of charge in it. It may be working fine. Try a nearly exhausted cell or two and see if you get .02 or .03A or a bit more from the 120VAC in that case.

tsmccull said:

The suggested 1 amp into the battery also may depend on the state of charge; the charger may be throttling back a bit if you put a cell into it which already had a good state of charge in it. It may be working fine. Try a nearly exhausted cell or two and see if you get .02 or .03A or a bit more from the 120VAC in that case.

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That makes sense as the cell was already up to 4.10v when I stuck it into the charger. I'll check once the cell is more dead.