In article ,
Floating Mind wrote:
It's my understanding that a person should never use a modified sinewave
inverter with a laptop, that we should always use pure sinewave
inverters with laptops, as the modified sinewave units are harmful to
the life of the laptop's battery.

Question #1: Is this true?

Short answer: no it is not true.

Longer answer:
Most, if not all, recent laptops use powerbricks that are of the
switching type. You can check easily: if it accepts 90-250V 50-60Hz,
it's a switching powersupply. Switching powersupplies don't care
what wave form it is fed, so any inverter will do fine.

Regards, ted