I don't see the original post, so I'll just add some comments at this point
in the thread.
I think most of the retail store 12V units are borderline junk, with varying
degrees of reliability. Paying more for one of these doesn't mean it's a
better designed unit, but more likely that it also serves as a flashlight or
When looking at the internal motors and pumps in these units, one might
ponder if they couldn't build a better quality air compressor/inflator with
some parts thay might have laying around, such as a decent quality cordless
power tool motor, a small pump, and a check valve.
Most good air compressors made for mobility are made with gasoline engines
as the power source.
Real electric air compressors for automotive applications are probably
limited specialty-type applications.
I haven't seen any of these units in automotive supplier's stores or
catalogs over the years.
Maybe the most commonly available compressors built with any quality would
be the pumps made for air leveling systems in some of the bigger cars.
A number of years ago, someone posted a commercially-made mobile air
compressor in the dropbox (12V or maybe 24V).
It had a heavy duty motor driving a 2 cylinder, single stage air compressor
pump by a belt.
The switch was a HD engine starter relay, so the current demand of the motor
was likely significant. There wasn't a storage vessel attached, although it
could've been under the vehicle.
Another unit that I saw in an automotive painting book in the 1970s, was an
improvised installation of a belt driven, 2 cylinder, single stage air
compressor pump with a 12V clutch, that was fitted to the vehicle's engine.
I think this installation was a project of fabricating custom brackets to
mount the pump so it could be driven by adding an additional belt/pulley to
This application definitely had a receiver tank mounted underneath the
vehicle, and all the necessary pressure control devices in place.
Taking a pressurized vessel out on highways would be unsafe, but venting the
pressure before driving it would make it safe.
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