running a/c on inverter

[Al]

David,
I agree with you... It is easy to tell where a bird is located by
this type of question. In the deep South, my bird does not start up
and go unless the generator is running powering two a/c units on the
roof and the one in the dash. Or I can arrive baked to a crisp in an
37' oven. The dealth of a diesel engine is not using it.

Al Johnson
'96 BMC B100
Mandeville, Louisiana

--- In WanderlodgeForum@yahoogroups.com, David Brady
wrote:
>
> From what I can find, running the genny should give us around
> 75% electrical generation efficiency at a powerfactor of around
> 1. Of course almost everything we power is inductive, including
> the AC's, so the powerfactor is probably closer to .8 which gives
> us an efficiency of around 65%.
>
> With the engine alternator, the alternator has an efficiency of
around
> 50% and the inverter 80% (probably optimistic) for a combined
> efficiency of 40%.
>
> If we assume the AC runs for an hour and is off for an hour, 50%
> duty cycle, then the alternator will consume 50% more fuel to
> power the AC's when the AC's are running, then the genny. When
> the AC's are not running, the alternator has a free ride, while the
> genny is still running.
>
> The question then becomes: during the free ride, is the genny
burning
> the extra fuel that the alternator required during the AC run time.
> Probably not. Also during this AC off time, the genny can provide
> power to other 120V loads, personal computers, refrigerator, etc,
> so the spent fuel is not a total loss.
>
> David Brady
> '02 LXi, NC
>
> Wilhelmus Schreurs wrote:
> > David:
> > Are you sure that running your big generator is more efficient to
run
> > one a/c, from the standpoint of burning fuel to the output of the
a/c?
> > With your engines you have two alternators, so each one would put
out
> > 50 percent only and then have 50 percent left over for other
items.
> >
> > Bill 84 FC 35 SB "$quanderlodge"
> > Terrace, B.C. Canada
> >
> >
> > ----- Original Message ----
> > From: David Brady
> > To: WanderlodgeForum@yahoogroups.com
> > Sent: Tuesday, July 1, 2008 8:25:03 PM
> > Subject: Re: [WanderlodgeForum] running a/c on inverter
> >
> > My LXi is set up to run one AC off an inverter and the
alternator, but
> > conventional wisdom is that you shouldn't do it. Steadystate
current
> > draw from the alternator is 150Amps. I want to preserve my
precious
> > alternator, so I always run the generator when I need my AC's.
> > Another point of view to consider the inefficiencies of the
alternator
> > in generating DC and to add on to that the inefficiency of the
inverter
> > to convert to AC to run the air conditioning. The generator is
more
> > efficient at generating the needed AC.
> >
> > David Brady
> > '02 LXi, NC
> >
> > coreyg67 wrote:
> >
> >> I'm trying to figure out a way to run 1 of my A/C units on the
> >> inverters and alternator. I
> >> would think with the two 2500 watt inverters, and the 300amp
> >> alternator, this would be a
> >> doable venture. Can someone tell me if, and how to do this task?
> >>
> >> Thanks
> >> Corey & Jenni
> >> 1996 PT42'
> >> Prosper, TX
> >>
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