In message , Claude
Hopper writes
Cheap inverters put out a modified sign wave that looks more like a
stepped pyramid than a sing wave. Not good for electronics and
transformers.

Cheap UPS devices designed to run servers and PCs only put out a
modified sine wave, they seem to cope fine.

About the only symptom I've ever seen from using devices on inverters
in my cars is that they generate a little more noise than they normally
would when under load. Other than that, nothing. All of my laptops have
been run in the car on inverters but I'd have to agree with another
poster, the most efficient way to do this is with a DC to DC converter.
--
Clint Sharp