Chargers and Amp Draw - not output

[konakid]

I'm confused and curious. Does the amp meter on the front of a charger indicate the amp draw or the amp output???

Reason for asking --- The older PowerWise 36v charger for one of my carts shows the meter going up to 25 amps (in the red) and it will stay there for 10-15 mins sometimes, before dropping below 20.

But I have it on a 15 amp circuit, and household plugs (what I charge from) are rated 15 amps. So, if chargers draw more than 15 amps - why are they all using plugs and receptacles rated at 15 amps?

[Volt_Ampere]

It is battery Amps not wall Amps. Chargers will draw less out of the wall in Amps than they deliver to the battery. (120V to about 36V conversion is either done with a transformer or a switching supply).

[trainsafe]

Wall amps will be about 1/3 your output amps.

[konakid]

Thanks Guys - the quick advice I get here is always appreciated.

[j.p.f.]

has anyone put a kill-a-watt on their charger to test it?

[Clemsoncartguy]

Originally Posted by j.p.f.

has anyone put a kill-a-watt on their charger to test it?

No, but I have thought about it and would if my cart were togeather. But you can figure it out. Watts equals amps times voltage.

[Volt_Ampere]

Watts only equals amps times volts if they are exactly in phase. On AC they often are not.

[Clemsoncartguy]

VA , you kind of lost me on that?

[JohnnieB]

Originally Posted by j.p.f.

has anyone put a kill-a-watt on their charger to test it?

Yes, but not recently and I didn't keep any records.

The branch circuit feeding the sub-panel in my detached garage is about 50' of 12Ga cable and I was looking at the drop in AC line voltage when the air compressor came on while a PW-II charger was pumping out about 20A and all the lights in the garage were on. If the drop was excessive, I was going to run a 10Ga cable, but it wasn't, so I didn't.

IIRC, the charger's AC amp draw was more or less what was stated on the label.

[JohnnieB]

Originally Posted by Clemsoncartguy

VA , you kind of lost me on that?

VA is referring to the Power Factor of the load. If it is purely resistive, then Volts times Amps equals Watts. If the load is inductive (Motors, transformers, Fluorescent light ballasts, etc.), then the Amps lags Volts, so Watts equal Amps times Volts times the Power Factor. Without the Power Factor, the apparent power usage is higher than the true power usage.

Needless to say, the electric power providers bill their customers for the apparent power usage rather than true power usage.


If you want to do some reading, here is a fairly decent overview of Power Factor: https://en.wikipedia.org/wiki/Power_factor