I would be very hesitant about using a square wave on a computer. Computers are very sensitive pieces of electronics that really like a flow of clean current.
Agreed. Because it's a laptop battery, rather than directly powering a desktop. I wonder if that mitigates the odd wave shape? I'm thinking of doing whatever business we have on the computer, usually working off its battery, then shutting the lid and plugging it in to recharge. Would that be safer?