Running roof air

cody · May 17, 2009, 07:57:12 AM

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 · May 17, 2009, 08:48:45 AM

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 · May 17, 2009, 08:50:37 AM

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 · May 17, 2009, 02:18:48 PM

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 · May 17, 2009, 02:28:17 PM

I thought tjhe Iggles used 12 volt sytems? Jack

cody · May 17, 2009, 02:43:43 PM

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

Lin · May 17, 2009, 03:56:37 PM

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 · May 17, 2009, 04:55:48 PM

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 · May 17, 2009, 04:59:56 PM

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

luvrbus · May 17, 2009, 05:34:24 PM

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

Running roof air

cody

cody