whats best generator/air compressor combo

**dajuanNonly** · 01-31-2012, 08:57 PM

im setting up my mobile van and can really use some insight from you veterens( i am amazed at the experience in these forums....thanks) on what is the most cost effective route in setting up a the right generator for the right air compressor. only thing i need an air compressor for is blowing out small crevices but if there is an alternative route to this im open to suggestion but the only hold up i have on my van right now is buying the right generator to power an air compressor please help!

**tuscarora dave** · 01-31-2012, 10:14 PM

I have to ask, how do you power your polisher and vacuum? If you really need a generator for working at sites with no power availability I can offer a few suggestions in general.

1. Record on paper, the voltage, the amperage and/or the wattage of everything that you will be using that is powered by electricity and add them all up for a total of amps or watts.

Wattage as a measurement of electric usage is voltage x amperage so if you have a tool that does not list the amperage but does list the wattage, simply divide the wattage by the voltage to get your amperage rating.

An example would be if you had a 1000 watt halogen light and needed to know the amperage, you would divide 1000 watts by 120 volts which equals 8.3 amps.

2. Figure out what tools you could possibly be running at the same time such as lights and polisher or 2 lights and a vacuum. Will you have a helper doing interiors while you are polishing paint? If so and you're working at night, you'll need your total amperage draw (how many amps you'll be using at any given time)

Let's say you have a helper and you are working at night with two 1000 watt halogen lights, a 12 amp rotary polisher and a 10 amp shop vac.

The two 1000 watt lights = 2000 watts/120 volts=16.6 amps. Plus your 12 amp rotary and your 10 amp vacuum. There you're possibly (at full load) drawing 38.6 amps continuous. Everything you're running is 120 volts so multiply 38.6 amps by 120 volts to get a total of 4640 watts of continuous electricity usage. You would want to purchase a generator that can power a 5000 watt load continuously.

Be mindful that a lot of generator/inverter manufacturers use the peak load handling numbers on their boxes and generator decals for marketing purposes so be sure to look at the continuous power handling numbers and not what is printed in large print on the box or the generator decals. Instead, look on the metal plate located on the actual generator part of the generator like in the picture below.

If I were going to be consuming 4640watts at any given time I would probably want a generator that would be able to handle 6000 watts continuously so that I wouldn't putting the max load on my generator all the time causing premature stator or rotor winding failure.

Regardless if it's just a polisher or an air compressor, your generator needs to be able to handle the current (amps) that the load will demand on a continuous basis, so if you will be using just an air compressor and nothing else and the compressor requires 20 amps to run under load you'd multiply 20 amps x 120 volts = 2400 watts + some room so you won't be over taxing the generator, I'd say a 5000 watt peak generator which would likely produce 3500 watts continuous.

There is also the the hertz to think about. hertz = electrical cycles per second. Most power tools run on 60 hertz. Most generators generate at 50-60 hertz depending on load cycles. (turning stuff on and off that slow down and speed up the gasoline engine during use)

Running a 60 hertz power tool at a constant fluctuation between 50 and 60 hertz is not necessarily good for the tool and could cause the tool to have a shortened service life. Exactly what happens here that is bad for the tool is beyond my level of knowledge so if there are any electrical engineers here maybe they could explain it.

That's the best I can give you on the subject, Hope it helps. TD

**dad07** · 01-31-2012, 10:38 PM

that is sound advice!

**dajuanNonly** · 02-01-2012, 07:56 AM

thanks dave.....once again this forum has enlightened me.....can't wait for the day when I can return the favor to some new detailer lol

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**art72** · 02-07-2012, 12:11 PM

Solid advice Dave. I just purchased a 3550 watt (continuous) generator to get started myself. Appreciate the insight on watts -vs- amps and "how to" calculate the demand.

**dajuanNonly** · 02-07-2012, 01:47 PM

Are u running an air compressor on that 3500 w

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**art72** · 02-07-2012, 02:21 PM

Not yet... like yourself, I just purchased my van and setting it up. So far, bought the pressure washer, generator, and a chunk of cleaning supplies, brushes, clay, wax, etc. *Looking into a 275 gallon water tank on craigslist next for $150.

So I haven't purchased my compressor yet, but was looking at a small 4 gallon Craftsman unit at Sears $180 (model#16638.) -However, I won't be using it for much other than some light cleaning, and maybe airing up a tire in a pinch. So I think the generator will run it ok.

Worst case, I figure I'll run the compressor solo, store enough air to do a job or get an air tank and air it up between jobs.

In my case I found a 3550w generator brand new in the box for $125 on Craigslist. I was gonna buy a new 5500w unit, but couldn't resist the savings.

Since, I don't imagine working on more than one car at a time (for now), I think the 3550w should be plenty of power. If the workload picks up, I'll buy a bigger generator.