Not quite correct
PWM is pulse width modulation. Instead of pure smoothly changing voltage from 0-120 volts it breaks the changes into a lot of little steps over the same 1/60 of a second. Some devices with microprocessors don't like this kind of voltage, generally ones with PWM of their own which are counting on the AC for timing signals. Microwaves are a good example. Mine runs at 1/2 time when on the inverter. Still cooks well you just have to double the time to get to to run what you really want. Things with motors don't normally care unless they have speed controls.
Hi Bill,
Need to comment here .
PWM does indeed stand for pulse width modulation.
However, what PWM does us take a constant voltage, and chop it into small slices, varying in duty cycle.
Light dimmers use PWM, as the filament evens out the power curve by the stored heat energy in the filament.
The concept you are thinking of is "modified sine wave", where a sine wave is constructed of varying height dc levels. On a scope it would look like an up and down staircase.
Microwave ovens hate modified sine wave, as do other devices that rely on a pure sine wave for reference, and amplification.
Modified sine wave was used in all the Xantrex freedom series inverter/ charger units.
Getting onto the subject of this owner's issue, I highly reccomend the Magnum Energy unit.
Unfortunately, Xantrex customer service has gotten downright crummy, and I would not currently reccomend their products.