Did you know that Steam Deck lists their battery capacity in watt-hours?

On the contrast with all those other manufacturers who write "3000 mah" without saying what voltage is that

The output voltage of the battery is 3.7 volts, while charging is 5 volts. What's the total capacity? no-one knows 🤷‍♀️

Steam Deck is 40 Wh - no uncertainty: you plug 5 volts charger with 3 amps you get ~ 3 hours of charging; 20 volts charger at 3 amps - 40 minutes. easy peasy!

Now I can tell my nephew why he needs that pesky math classes 🤣

P.S. 40 Wh is 3 hours of heavy gaming but oh boy I'm grateful to be able to lay on the coach with the Deck. And tbh, it's not that healthy to play 3 hours in a row, gotta get a break sometimes!