SunGoldPower 3kW 24V - how much power to run the charger?

[glock35ipsc]

I'm sure this is a simple answer, but I've probably overthought it to the point that I'm now confusing myself.

I have a SunGoldPower 3kW/24V inverter charger. I operate it as a battery backup, so the inverter only comes on when the mains go down. I also have 2500 watts of solar connected.

My question is...... when charging the battery from the on-board AC charger, either from the mains or a gas generator, how much power is required to operate the charger itself? It is using 120VAC to power the charger, but output is 24VDC (25.6V nominal, or up to 28.8V I suppose). So, is it using 120VAC * 40A = 4800 watts? Or would it be 25.6VDC * 40A = 1024 watts (+/ for exact voltage)?

I don't know if it's a simple as that, or if there is some conversion I need to take into account considering its AC in and DC out. I would like to know this to be sure my generator will handle it and that it's not being overloaded.

 

[DIYrich]

Watts in - conversion loss = Watts out. Watts out - battery loss = Watts stored in battery

 

[dahluwalia]

So can a portable generator power the machine up with to charge batteries or do you need a separate charger for thst

 

[MichaelK]

Why don't you determine this yourself, and then get back to us with the real numbers. Get a clamp meter that can read both AC and DC current. The one I like now is the Uni-T 216C because it can also read inrush current from starting electrical motors.

While charging, measure the incoming amperage on your AC line, and multiply that by your AC voltage. Then measure the outgoing DC amperage to the battery and it's voltage. Dividing what goes out by what goes in tells you what your efficiency is.

Remember, the inverter itself will be consuming power just being on, so you need to factor that into your efficiency calculations. I'd take the measurements in the morning after some overnight depletion, so you get the best answer. You are likely to get the least accurate number as the battery approaches full charge.