This one states “modified sine wave.” I wonder what that means exactly in comparison to what you were mentioning. It looks like items marked with “pure sine wave” are the ones you’re describing based on the prices i’m seeing. An equivalent unit to mine with that designation runs about $300, so they’re proud of them for sure.
So it’s a square ish wave vs a sine wave. Cheaper chargers do heat up more with a modified wave, and some of them even sound different while charging. I’m assuming it’s because the capacitors are doing a bit more work smoothing out the signal and the big coil in the center of the charger is vibrating differently to go along with the new waveform.
These are I think the “cheap” class. Disposable things not meant to run 24/7 for years. There’s another big price bump to go to that class with pure sine wave.
I had a look at gennies and inverters for whole house backup power… (Turns out I can run the house on about 150w)
I’m fairly sure the “modified sinewave” is just another form of “simulated” or “approximated”…a lot better than a squarewave output but it’s still not pure sinewave. The waveforms provided by Marsrover001 show the difference quite well. As I said earlier, some chargers and power supplies may not be too bothered by a “modified sinewave”, but there will be some that are.
I tend to be very conservative when it comes to providing power to expensive stuff like a computer, but if the device on the output end of the charger or power supply is easily and inexpensively replaced then I’m willing to take a chance on using a simulated sinewave output inverter. I keep in mind that it isn’t just the charger or the power supply that may fail, but if the inverter-connected charger or power supply fails catstrophically it may take the computer, or phone, or display, etc with it to the recycle bin or my salvaged parts shelf.