Running electric compressor on inverter

Lin · September 12, 2010, 10:18:53 PM

We are getting ready to leave tomorrow for Zion and Bryce in Utah. I was doing some things today and tried to air up the bus by running the electric compressor through the inverter. It did not work out well. The compressor would stall and the 250 amp breaker to the inverter would pop. Is it typical that something like a compressor has trouble running on modified sine wave?

On the lighter side. I wanted to measure my total height which I guessed to be short of 11 feet. I was surprised to find it measured about 11.5 feet. Then I looked down and noticed the bus was still up on the ramps. Now don't you feel safe on the road knowing I also adjusted my brakes?

Tony LEE · September 13, 2010, 03:52:23 AM

Air compressors and similar AC motor-powered appliances can draw up to 7 times their normal running current for a short period after they are switched on. Although most inverters have a short term surge rating, often they just can't react fast enough to supply the current while still maintaining the correct voltage. The motor just sits there stalled and the inverter drags a lot of current until the fuse blows or it trips out on overcurrent.

What rating is the compressor (Amps, hp) and what rating is the inverter

bevans6 · September 13, 2010, 04:58:48 AM

As said above, compressor motors are notoriously hard to start. I have a little 5 cfm air compressor, I tried to use it with my Honda 2000 and it was a bear to start. The problem with compressor motors is you have to start them under load so the inrush current is correspondingly higher until it starts to run. Modified sine wave just makes it all worse, by a decent factor around 20%. Motors hate MSW.

Brian

TomC · September 13, 2010, 08:43:54 AM

I have a modified sine wave 2500 watt Trace inverter. Strange as it sounds, the stove hood runs slower on inverter, yet the bathroom electric wall heater and my wife's hair dryer run normally. Most electric motors need a true sine wave inverter to run properly. Personally-I think inverters should be used for miscellaneous minor electrical loads like coffee maker, microwave, hair dryer (heavy draw but short time), computer, TV, electronics, lights, refrigerator, etc. When it comes to running an air compressor, or more heavily an air conditioner, just start the generator. I realize that Sean runs one or two of his air conditioners on his 4000 watt inverter, but he also has a gigantic battery bank and is also an electrical engineer.
When I bought my inverter, I could stack them to make 5000 watts. I asked the owner of the electronic shop about and she (yes a woman) said that if I had a good Diesel generator, to just run the generator-and that's what I do. Meantime, she lost an additional sale! Good Luck, TomC

luvrbus · September 13, 2010, 09:15:57 AM

OT a little LIn but you won't like the deal they have at Zion now the Seniors pass will get you into the park but will not cover the escort fee to the camp ground 25 bucks I would not pay it I turned around.

good luck

buswarrior · September 13, 2010, 09:48:16 AM

What's the battery bank condition?

A little low, a big load, lots of amps flowing...?

Did it work before, or is this the maiden flight?

happy coaching!
buswarrior

Lin · September 13, 2010, 11:05:45 AM

Thanks for the answers. The compressor is fine on the generator. Clifford, I have the National Parks senior pass. It is the best deal left in
America. Since we live near the park in JT, we use it a bit without leaving home. I was told that the campground rate for seniors is half price too, but don't no anything about the "escort fee". Is that all year or just for the busy season. We are going to be staying outside the park anyway in the nearby town of Hurricane. We can always move into the park if we want.

luvrbus · September 13, 2010, 12:23:54 PM

Lin, it is going to cost you 25 bucks to get through the park on hi way 9 only way around it take 14 at Cedar City across or 59 and 359 dropping back to the AZ side they will not half the rate to get through the tunnels in Zion

We really enjoyed Bryce stayed at the first campground on the right on the way up 7.50 per nite with our pass.

good luck and drive safe

Mex-Busnut · September 13, 2010, 08:00:20 PM

Quote from: luvrbus on September 13, 2010, 09:15:57 AM
OT a little LIn but you won't like the deal they have at Zion now the Seniors pass will get you into the park but will not cover the escort fee to the camp ground 25 bucks I would not pay it I turned around.
good luck

Shame on you, Luvrbus! This here is supposed to be a family-friendly board, and you talking about an escort service!