<VV> 12v A/C

[James Davis]

A couple of observations.
12SI Delco alternators can be modified to produce 140 amps @13.7 volts.  I
had a 120 amp 12 SI on my Corvair powered Ultravan #388.
The alternator was rated 120 amps @ 6,500 alternator rpm (about 4,500
engine rpm).  At 3,000 engine rpm, produced about 70 amps  The halogen
headlights, windshield wipers and defroster fans draw around 60 amps in the
Ultravan.  The system worked well except you had to change the fan belt
about every 6,000 miles.  The same is true with my 1961 Rampside with A/C
and gas heater.  The 120 amp 12SI eats fan belts.

The UltraVan 8'x8' x24' can with a 1968 Coleman mach 10,000 btu roof A/C.
It had no trouble keeping the coach cool at rallies in Christmas,
Zephyrhills and Avon Park, FL during April/May and Sept/Oct.  I admit to
avoiding the Jul/ Aug time frame.
Jim Davis

On Tue, Dec 2, 2025 at 3:24 PM Frank DuVal via VirtualVairs <
virtualvairs at corvair.org> wrote:

> I'm also very skeptical that 12 K BTU would do anything in Florida heat
> and humidity! At least in the daytime.
>
> Solar loading of a hardly insulated car is a LOT!
>
> The belt wrap of the Corvair alternator limits the output to under 100
> amps, even if the alternator is capable of more. Corvair generators top
> out about 35 amps unless some very rare high output model.
>
> Frank DuVal
>
> On 12/2/2025 11:20 AM, Mike Thomas via VirtualVairs wrote:
> > 12,000 BTU would require around 293 amps @ 12 V, or about 10 times the
> > capacity of an early Corvair's electrical system.  I'd be very skeptical
> of
> > this system...
> >
> > Mike T.
> >
> >
> >
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