Can 20 year compressor overheat the 20V?

[Huw Powell]

So we are talking 2-3 hp depending on conversion efficiency.

On 7/30/2012 3:44 PM, Joshua Van Tol wrote:
> Most auto ac units are rated more like 15-20k btu. Heat gain is
> ferocious because of the windows, and poor insulation.
>
> Efficiency isn't a priority, and most systems run fresh air all the
> time, unless forced into recirc.
>
> Josh
>
> On Mon, Jul 30, 2012 at 2:03 PM, Huw Powell <audi at humanspeakers.com
> <mailto:audi at humanspeakers.com>> wrote:
>
>     Just to play with numbers a bit...
>
>     a 6500 BTU house window unit, recommended for a 250 sq ft room would
>     use about 50 amps on 12 volts:
>
>     5.7 a at 110 v = 627 w
>
>     627 w at 12 v = 52.25 a
>
>     To make a huge assumption, that running one off house AC is roughly
>     as efficient as running the compressor directly, that's like adding
>     "half an alternator on full load".
>
>     Plus whatever the interior fan uses on "high cool" mode.
>
>     So while it is certainly a load on the engine, it shouldn't feel
>     like towing a trailer.
>
>     Another random note, the numbers above are for a new, modern, Energy
>     Star* AC unit.  The 20 year old system under discussion is probably
>     less efficient to start with, and might be quite a bit worse by now.
>
>     *My new (ten years ago) Energy Star refrigerator was about 30%
>     larger than the late 70s era unit it replaced, and my electric bill
>     went down $20 a month (135 kwh at my nuclear rates).  Your mileage
>     may vary.  It might not be possible to match modern efficiencies of
>     that sort in an automotive system, especially a retrofit.
>
>
>     On 7/30/2012 2:35 PM, George Selby wrote:
>
>         At 01:56 PM 7/30/2012, you wrote:
>
>             Regarding the drag: my compressor is pumping fine, but when
>             it turns
>             on, it
>             feels like I'm hauling another type44 on my back. Any remedy
>             for this?
>
>
>         Double the boost?
>
>         In actuality AC is a huge drag on the engine (Maybe not in
>         Canada, but
>         down here in the southern US it is.)  Due to losses in converting
>         energy, the engine bay probably sees 4 times as much heat added
>         when the
>         AC is engaged as is removed from the interior.  And most auto AC
>         systems
>         do produce an icy blast, in fact the average car system would cool a
>         house quite well.
>
>
>         George Selby
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