Wattage on a Converter

[Bob Landry]

How is power figured on a converter? For instance, a 45W converter, if it's figured on output, would only be putting out a little under 4Amp at 12V. Am I looking at this correctly?

[Festus2]

Bob-
My understanding is Watts=Volts X Amps. In the example you cited, yes it would work out to 3.75A at 12 volts.

[PARAPTOR]

Originally Posted by Bob Landry

How is power figured on a converter? For instance, a 45W converter, if it's figured on output, would only be putting out a little under 4Amp at 12V. Am I looking at this correctly?

Yes, if I had a box with a rating of 45W. I would assume it was the OUPUT rating and if box was 12Vdc output then yes little under 4 amps outpuT. MOST converters I have seen were rated based on AMPS (exp 45A) out. With under 4amps achievable with a simple output diode bridge.

[Bob Landry]

Thanks, I thought that's what it was. it just didn't seem like 4A was enough to power all of the overhead lights and controls for the appliances.

[Festus2]

Bob-
How did you determine that the converter had a rating of 45W? I'm with you, I don't see how, if its output is 3.75 Amps at 12 volts could possibly power all the lights plus other "stuff". Each one of those incandescent lights probably draws about 2amps ...

So you can see that 45watts won't get you very far. Surely, the converter puts out far more amps than 3.75. At this rate, it would take forever to even charge your batteries. If the converter's output is 3.75 amps, I don't see how any of the items that use 12v could possibly run.... lights, fridge, furnace fan, water pump,........

Something is amiss in the 45 watt converter rating.....??? I checked my WFCO manual and can't find any information there about its wattage rating.

[Bob Landry]

You'll get no argument out of me on that one. It seems a little light to me also. I'll call Monday and see if I can get some clarification. The main thing I want to know is how much AC current it's drawing and my EMS will tell me that. I'll just turn on everything I can and what ever it draws, I'll call max..

[Bob Landry]

Duh!!! <Slapping forehead> It's a 45 Amp converter, not 45 watts. I think I've got too many projects going on.. The input power is 780 watts, so at 115V, that would be a little under 7A.

[PARAPTOR]

When question came up I assumed Bob was working on some project Because of amperage capacity I assumed he was not referring to his rigs main converter His main converter has to be much larger than 4 amps

[Festus2]

Bob-
If the converter is rated at 45 amps which makes much more sense and you have 110v input, doesn't that work out to a maximum wattage output of 4950 ? (watts = amps x volts). I guess this would be its AC rating but not sure how relates to its DC output.
Perhaps someone with electrical expertise can figure this out for me and explain it in simple terms will chime in.

I realize the converter has two "sides" to it - one for AC and another for DC. How do you figure out the amp output for the DC side?

Please, no theories or speculating. Thanks.