Small AC motors and Inverters

OK OK OK

1000W Pure Sign Wave inverter it is.

Chris Bryant wrote:

Heh. Have something similar as a backup. But it takes forever.

Also have a classic hand-beater for eggs, but an electric hand blender is nice to have.

Modified Sine inverters are dirty power. The voltage is erratic and as a HIGH chance of damaging sensitive electronics.

The cost of a Pure Sine inverter is well worth the cost of replacing a Mac's power board, or that neat cordless drill charger you had....had.... had...

Watch this video.

https://www.youtube.com/watch?v=wimTJw_Gpgk

It explains visually and audibly why a non PS inverter should NOT be used.

While the inverter needs thick wires and close to the batteries, the 120v output does not. You can run a normal extension cord where ever you need it.

My PS inverter has three 120 plugs. I wired them with household wire and installed plugs inside the camper.

I made a plug system/switch so that the microwave can be used off the inverter, but not energize the whole camper.

Most PS inverters also have remote power on abilities. This allows you to turn it on inside the camper easily.

brulaz wrote:
.. pure sign (sic) wave inverter and wire it close to the batteries. For a coffee grinder? sheesh ...

Yeah, that's the price of being off-grid!

2oldman wrote:
From Wikipedia:

Sine wave inverters with more than three steps in the wave output are more complex and have significantly higher cost than a modified sine wave, with only three steps, or square wave, (one step), types of the same power handling. Switch-mode power supply (SMPS) devices, such as personal computers or DVD players, function on quality modified sine wave power. AC motors directly operated on non-sinusoidal power may produce extra heat, may have different speed-torque characteristics, or may produce more audible noise than when running on sinusoidal power.

From me:
Surge wattage can be up to 4 to 5x running wattage.

Ok, maybe 800-1000W surge for the coffee grinder. That's probably what the truck's 400W continuous puts out. Then there's the ~200Whand blender ... and going to pure sine wave ... not cheap.

BFL: the 12V socket is one I wired myself with rel. heavy wire and 10A (?not sure) fuse in the WFCO. Only about 1' from WFCO. Still, if the surge is 1000W at 13V, that's 76A. But the fuse didn't blow; maybe slower response than the old inverter's overload circuit?

Guess it would be best to get a pure sign wave inverter and wire it close to the batteries. For a coffee grinder? sheesh ...

Starting current depends on the kind of motor (and its load, etc.) If it's a shaded pole induction motor, which would be my guess, it's probably not too much different than the operating current. Do note that the power factor could be somewhat poor, so the 120W motor could consume more than 120 VA.

How well the motor functions on a non-sinusoidal power input also varies with the kind of motor. An induction motor typically will have somewhat lower torque (and hence speed) and run somewhat less efficiently (warmer), but not unreasonably so unless it's sized very marginally for its task or run for very long periods of time (or both). A universal motor with brushes will be relatively little affected by the differing waveforms.

BFL's suspicion that the inverter is shutting down from undervoltage at its input rather than overcurrent at its output has merit. I think most inverters—at least inexpensive ones—are mainly protected from excess power draw by the DC input fuses. I may well be wrong.

NOTHING is designed to work on MSW.

If it works on MSW great. Poor performance in general should be expected.

Try the smaller inverter with fatter wire to the battery. If using the RV 12v socket, that can only handle about 8 amps DC maybe 90w due to its thin wires.

ISTR the 12v sockets in trucks and cars are heavier duty than the 12v sockets in an RV usually are.

From Wikipedia:

Sine wave inverters with more than three steps in the wave output are more complex and have significantly higher cost than a modified sine wave, with only three steps, or square wave, (one step), types of the same power handling. Switch-mode power supply (SMPS) devices, such as personal computers or DVD players, function on quality modified sine wave power. AC motors directly operated on non-sinusoidal power may produce extra heat, may have different speed-torque characteristics, or may produce more audible noise than when running on sinusoidal power.

From me:
Surge wattage can be up to 4 to 5x running wattage.