REFLECTOR: A/C (was Re: GRT Displays overheating - Anyoneelseseethis?)

[Lawrence Epstein]

Toyota makes a fully electric 12V A/C unit for the Prius (Ford has 1 as
well). I am planning on adapting it for the Velocity. I am pretty sure it
has a 20 Amp fuse in the Prius (I will look when I get home). Considering
that my panel will be fully electric, that probably means a 2nd Alternator.

Larry Epstein

On Wed, Jul 11, 2012 at 4:10 PM, Mark Magee <edjonesbrady at gmail.com> wrote:

> Sid,
> Here is the specs on the unit I discussed. I have run it on a 500w sine
> wave inverter (1000w surge).
> I pulled it apart and the critical parts weigh about 7 lbs.
>
> http://www.toyotomiusa.com/products/portableairconditioners/TID-1200.mv
>
> Can you tell me from this data that it requires 100amps VDC via 92%
> efficient sine wave inverter?
> My calculations are I/2 that, yet I don't claim to be an EE.
>
> Mark B. Magee
> Sent from IPhone 4
>
> On Jul 11, 2012, at 1:45 PM, "sbjknox" <sbjknox at earthlink.net> wrote:
>
> >
> > ----- Original Message ----- From: "Mark Magee" <edjonesbrady at gmail.com>
> >
> > Subject: Re: REFLECTOR: A/C (was Re: GRT Displays overheating -
> Anyoneelseseethis?)
> >
> >
> > [snip]
> >> I pulled apart a small roll around 4,000 BTU A/C that pulls 4 amps on
> the AC
> >> I Used camping with the kids. I think 4000 BTU's of A/C would
> marginally cool
> >> an XL cabin on a 100F OAT day. The good part is the whole unit can be
> run
> >> on an inexpensive 1000W sine wave inverter that factoring in 8%
> efficiency
> >> loss it would still only pull about 50 amps on the 12V. I'm hoping a
> second
> >> alternator, possibly a  supplenator would fit the bill and double as a
> back
> >> up alternator. As well I might install some 110V outlets for use in
> flight
> >> after the A/C was shut down in the cool air.
> >
> >
> > Some rather creative math going on here...
> > Strictly speaking, you can't equate BTU and Watts but common useage of
> BTU when refering to air conditioning actually is BTU/hour so that 1000
> Watts = 3415 BTU/hr and 4000 BTU/hr equates to about 1171 W.
> > But the real issue is with the current at 12Volts.  Even if you had a
> sine wave inverter with 92% efficiency (which I believe is overly
> optomistic) the current at 12V is
> > (1171W)  /  (12V) / (.92)  =  106 AMPs!
> >
> >> I think the whole arrangement with alternator might add 12 lbs.
> >
> > For 4000 BTU/hr, not likely...
> >
> > However,  your 4000 BTU roll-around unit could not have produced
> anywhere near 4000BTU/hr if it was only pulling 4A from the 115VAC line.
>  (4A)  x (115V) = 460 W.
> > (460W)  x  (3.415BTU/hr/W)  =  1571 BTU/hr  at 100% efficiency.
> >
> > So, IF your roll-around unit would   "...marginally cool an XL cabin on
> a 100F OAT day.", then a much smaller (than 4000 BTU/hr) A/C might work and
> your current draw at 12V would perhaps be acceptable.
> >
> > Sid Knox
> > Oklahoma
> >
> > Velocity  173 RG  N199RS
> > Starduster  N666SK
> > KR2         N24TC
> > W7QJQ
> >
> >
> > _______________________________________________
> > To change your email address, visit
> http://www.tvbf.org/mailman/listinfo/reflector
> >
> > Visit the gallery!  www.tvbf.org/gallery
> > user:pw = tvbf:jamaicangoose
> > Check new archives: www.tvbf.org/pipermail
> > Check old archives: http://www.tvbf.org/archives/velocity/maillist.html
>
> _______________________________________________
> To change your email address, visit
> http://www.tvbf.org/mailman/listinfo/reflector
>
> Visit the gallery!  www.tvbf.org/gallery
> user:pw = tvbf:jamaicangoose
> Check new archives: www.tvbf.org/pipermail
> Check old archives: http://www.tvbf.org/archives/velocity/maillist.html
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://www.tvbf.org/mailman/private/reflector/attachments/20120711/b3b1cdc1/attachment.html>