Running roof air

[cody]

A couple of nights ago I found out I could probably run a roof air off my alternator using my new inverter, I wasn't feeling good enough that night to understand what I was told, hoping for a replay?  I've got a magnum 2812 inverter thats pure sine wave and 2800 watts continuois with a surge of 3900 watts, a 4 battery bank with AGM's and the original huge alternator that looks like a 30 gallon drum lol, it's not made of wood so I'm cornfused as usual, I'm not even sure I heard it all correctly so if I didn't then we'll all laugh over it and at some point I'll glue your cabinet doors shut lol.

[Lin]

As I understand it, 2500 watts should keep one rooftop going safely.  If you have the original 250 amp/24 volt alternator, that will give you about 6000 watts to your inverter which, at 2800 watts, should be fine.  I like rounding things off.

[JackConrad]

Cody,
  Look at the specification tag on you AC and see how many amps it draws. Multiply those amps X 120 (volts).  This is the watts required.  Remember most inverters have an efficiency of 85-90%.
 Divide watts required by 12 (battery voltage) to determine alternator output required to "keep up" with the AC.  Maximum alternator output is probably at and engine speed of 1800-2000 RPM?  Jack

[Nick Badame Refrig/ACC]

Hi Cody,

Maybe I missed something. You said you have a 2812, that's 12v. Your bus alt is 24v.  If you have a vanner that will have a 12v tap but, only 50amps output.

What's your plan?

Curious
Nick-

[JackConrad]

I thought tjhe Iggles used  12 volt sytems?  Jack

[cody]

My bus is 12 volt. Lin mistakenly posted the voltage at 24 volts.

[Lin]

My bad.  The numbers would still work though since a 12 volt 50DN alternator would still be putting out around the same wattage.  Remember Abbot and Costello, "Watts are first."

[Jerry Liebler]

Lin,
   The 12 volt 50DN puts out about 3600 watts while the 24 volt is good for about 7,000 watts. 
Regards
Jerry 4107 1120

[Lin]

So the 12 volt 50DN is still only giving 300 amps?

[luvrbus]

Lin, My 12 volt Eagle with a 50dn has 300 amp max at 2100 rpm 200 amp at idle (650 rpm)     good luck