Faulty assumptions regarding battery-operated air compressor?

[PatLee]

I just purchased a Viair air compressor that uses batteries in either the tow vehicle or the trailer to power it. The user manual "strongly recommends you keep the vehicle's engine running while using the air compressor to prevent discharge of your vehicle's battery." A friend who owns the same compressor, hooks the cables to his Airstream's AS AGMs when trailer is detached from the TV. I would like to do the same. My AS batteries are AGMs which my solar panels re-plenish, right? Which means I don't need to worry about them discharging, right?
Besides these 2 assumptions, my basic question is: What is best practice when using a battery-powered air compressor? This is the compressor in question.

[fran&frank]

You still want to watch the state of charge of the AGMs in your trailer and not discharge below 80%--Frank

[Lumatic]

Sounds to me the manual is talking about a compressor being used to fill tires on a motorized vehicle so you have enough battery to start the vehicle.

[ROBERT CROSS]

If I was pumping up a completely flat tire I would connect our Vair to the running TV.
For topping up I connect to the AS thru the 7pin umbilical.

Bob
🇺🇸

[Mollysdad]

I have the Viair 400P and always hook it to the trailer batteries.
(I know, I don't always follow directions. )
So far, never a problem. If you need to bump a tire from 60 to 70 psi. it takes about a minute or two.

[GetawA-S]

The nameplate suggests 30 A draw. This will outdraw a 400 W solar system under all but ideal conditions.
Results will vary, so watch the amps/battery charge indication to keep in the safe zone.

[drbrick]

I always connect our Viair to the TV with engine running - the power draw is very high. We had a slow leak (nail) while camping for 14 days - tire pressure down to 10lb - it took a while - a long while to inflat to 65lb... the draw would be hard on the battery without the engine running. I would think a "short" top up it wouldn't matter so much???

[pteck]

Not a big deal running off the trailer batts. 30amps is peak at 150psi. Nominal draw is much lower. Even 30amps for intermittent tire fill is not a big deal.

Most of us have two batts in tandem on the trailer, halving the power draw to each, or 15 amps per batt worse case-scenario. One can keep the TV running and the umbilical will further supply some current support. If we assume ~10amps from the umbilical, then it's 10 amps from each batt. If we assume there's solar, less still.

Go for it.

[OTRA15]

Any time you are using a battery to power anything, you have to monitor the electrical discharge, and ensure that you do not damage the battery, or reduce its usefulness for other purposes or its lifespan due to excessive discharge.



We use the van's batteries and keep the engine running. Using the trailer's batteries, especially with solar charging, is fine, but as others have said you still have to monitor the battery voltage.

"There ain't no free lunch," as Wally used to say!

[PatLee]

Thanks everyone for your replies. Safe travels!

[Ron1934]

For my Husky AC/DC air inflater I power with either my Eco Flo Delta solar generator 30lbs that provides both AC115v or 12v DC or 12v DC from my Mazda CX 9 TV battery. The Husky maxes out at 100psi.