Originally Posted by MarkMcK
Why should I bother with a pure sinewave inverter if it's going to go back thru my laptop power adapter and generate DC. I could see where if you were going to use an AC powered device of some kind it may be a 'player'.
Is there something I'm missing here???
I believe it's a question of electrical noise.
A pure sine wave has exactly one frequency, with no harmonics. A modified sine wave inverter is producing a distorted waveform that has harmonics which mean electrical interference. Even though you're not using the AC sine wave directly the noise might be able to make it through the laptops adapter. So that electrical noise on the power could be a problem for your laptop, in theory at least.
But I have no idea how much of a problem it is to modern laptops. After all, we trust our PCs to inexpensive UPS systems all the time and I don't think any of them produce pure sine wave power when on battery. Of course they probably have a certain amount of power filtering built into their surge suppression.