Running a/c off inverters?

[mymyst]

With the large AGM battery bank and 4.8kw available power off the inverters on the Anthems, has anyone run ONE of the house a/c's off the inverters while going down the road? It seems one of the house a/c's would help supplement the bus dash air just fine, running all three off the generator is overkill for us and 'underloads' the genset most of the time. and I have yet to see a coach where dashair alone will keep the bus comfortable going down the road, especially in the more humid climes we travel. Anyone done the electrical math out there, or just 'tried it'?

[DebbieMH]

The a/c will not operate w/o shore power or generator power.

[mymyst]

hmmmm..DebbieMH, can you elaborate? what precludes one from doing so?

[DebbieMH]

When I am not plugged in or have the gen on - if the a/c is set for cool and auto - it won't turn on. At least mine won't. The washer dryer won't work either. If yours will - more power to you!

[brobox]

The A/C are not wired to the inverters, nor are the washer and dryer. Too much demand that would cause damage to an inverter. We have been running the generator with one roof air ever since we moved to FL years ago.

[docj]

First of all, your MH probably isn't wired to power the A/C off of the inverter because it isn't practical. So you'd have to do a major rewiring in order to try it.

But, if you do a few simple calculations you will see that simply isn't a practical solution. An A/C will draw ~13-15 A when running (not even considering starting surges.) That translates into >130-150A at 12V, not including losses in the inverter. Assuming the inverter is 80-90% efficient pushes these numbers to well over 150A. At that kind of discharge rate even the best 6V AGM battery isn't going to have much capacity. You probably could get it to work but I doubt that it would even last an hour.

I'm not sure why you are concerned about "underloading" your generator. A diesel genset isn't going to be all that upset by having to run just one A/C. That's what the rest of us do with ours.

[Knightab]

I don't see why it wouldn't but without knowing how large your bank is and the amp hours available it's hard to say. If the ac draws 10amps on a 120 circuit you will be drawing approximately 100 dc amps plus inefficiencys.

[MRUSA14]

Not only would it discharge your batteries in well less than an hour, but after several such uses the batteries would be ruined.

[mel s]

Originally Posted by mymyst

With the large AGM battery bank and 4.8kw available power off the inverters on the Anthems, has anyone run ONE of the house a/c's off the inverters while going down the road? It seems one of the house a/c's would help supplement the bus dash air just fine, running all three off the generator is overkill for us and 'underloads' the genset most of the time. and I have yet to see a coach where dashair alone will keep the bus comfortable going down the road, especially in the more humid climes we travel. Anyone done the electrical math out there, or just 'tried it'?

mymyst
I would not attempt run a RV roof air conditioner on inverter power.
If you want more A/C on the road than your dash air can provide use your generator to power one or more of your roof A/C units.
Mel
'96 Safari

[dusty56]

MyMyst has a point. The king aires are designed to run one ac without the generator on while going down the road. They also have 16 batteries. So the answer is it can be done. I guess load mgt, inverters and alternators can do it. Oh yeah they have 600 watts of solar panels on the roof. What it would take is a math question for volt doc.

[MRUSA14]

Originally Posted by dusty56

MyMyst has a point. The king aires are designed to run one ac without the generator on while going down the road. They also have 16 batteries. So the answer is it can be done. I guess load mgt, inverters and alternators can do it. Oh yeah they have 600 watts of solar panels on the roof. What it would take is a math question for volt doc.

They are running that AC from the engine alternator, not the batteries. The batteries are the weak link here. Running off the engine alternator is similar to running the AC off your Onan generator.

[RAM427]

Re running an A/C on an inverter. The rough calculatons were correct re 120-150 dc ampdraw for one a/c but the poster was assuming running down the road supplementing the dash a/c with, therefore, the engine alt putting out a (granted, near max) 150 amps as well. The batteries should maintain, not considering the a/c is not currently wired to the inverter.

Re poster's concern about generator "underloading". Most generator manuals advise against diesel or gas underload running as is very inefficient and not "good" for the generator engine.

[docj]

Originally Posted by RAM427

Re running an A/C on an inverter. The rough calculatons were correct re 120-150 dc ampdraw for one a/c but the poster was assuming running down the road supplementing the dash a/c with, therefore, the engine alt putting out a (granted, near max) 150 amps as well. The batteries should maintain, not considering the a/c is not currently wired to the inverter.

Re poster's concern about generator "underloading". Most generator manuals advise against diesel or gas underload running as is very inefficient and not "good" for the generator engine.

My understanding is that if you draw ~150 continuously off the alternator you probably will cause its early failure. Many of us use our generators to recharge house batteries after boondocking rather than letting the alternator handle the large load.

As for the harm done to a diesel generator by partially loading it for a few hours, rarely when anyone runs one is it fully loaded, anyway. Even if you have two or three A/C's on they rarely will all have their compressors running at the same time. I'm really not worried about the harm done to the Onan.

[DMTTRANSPORT]

Oh! Don't run the dash A/C as I have been told it takes 60 HP to run the Hyd motor that turns the fan......