I'm trying to put together a "mobile detailing van" for my boss. We've got an old chevy 3500 and I'm putting at 225gal water tank in it with an RV pump to supply water to the gas powered pressure washer. Rob also wants an inverter so he can run a shop vac. My math says I need 1440 watts. 12amps times 120volts. I'm thinking a 2000watt unit from harbor freight. We're only going to use it about once or twice a week to wash busses after the drunks get done with them on Saturday nights. How's my thinking so far?

My experience is they aren’t very reliable. I’m guessing here, but I think the money it would cost for a good one that size, you’d be far better off with a generator.

Math is fine.

If you ain't gonna use one much, I'd not be scare of a cordless shop vac and a few batteries. Whatever works

I cobbled together a leaf blower motor and an airtight bucket for REAL portability....use it for cleaning bedrock...in the boonies.

Better have a good battery bank because 1440 watts will draw down an inverter on one or two batteries,quickly....

DonRowe inverters has a calulater for battery draw with an inverter.

Run the numbers here....



Battery draw

++

Honda 2kw. Usable for other things. Vent it out the sidewall.

Was planning on having to keep the engine running while the vacuum was running.

Dunno. Going to depend on the inverter, those motors are a difficult load to drive. My neighbor had a solar setup for his garage and basement with some fairly nice inverters. Would not drive his shop vac or his wife's hair dryer. The inverter would shut down. Would run the garage door openers though.

Dunno,I have a Dewalt air compressor that none of my generators(5K surge) will start...The surge of any appliance is what kills the ability to run it off of generators/batteries or inverters...

I've got a little nail gun compressor that won't run off of certain outlets in my house with an extension cord for the same reason. Voltage drop across the cord. I'll continue the research.

More than initial surge it's an inductive load. See "power factor."

Pretty sure a shop vac is a universal motor, not an induction motor. You could just connect several batteries in series and run one on DC. The number of batteries would determine the voltage and therefore the speed it runs at. Would still kill your batteries fairly quickly.

With the engine running and an inverter, you would still drain the battery since that much power is going to be around 150 amps at 12V. Most alternators are only rated about 100 amps and that would be at full speed.

A generator is probably your best option.


Jerry

as jerryv says----when I inquired about a similar project some years ago the company rep said there was no way to do it other than installing a second high capacity alternator and running the engine. one alternator is not enough to keep the battery up for very long.

These are actually pretty easy to build....

The motor has inductance and is an inductive load. That distorts the waveform and is hard for inverter control circuitry to manage. Can bugger up a generator too if the generator doesen't have enough capacity.

Spend the bucks, get the Honda generator, you'll be happy.

I run a shop vac off an inverter almost daily. Sometimes up to 10 times daily from 2-10 minutes at a time. Has the same inverter 8 years. Truck battery lasts 2-3 years in our heat....

Just get a bigger type. I clamp to my truck battery. If max juice needed turn on truck....

I ran a television, Laptop and a microwave off a 3k one for a decade in the semi.