So many times I forget to plug the deck or someone uses the charging cable for something else and I come back to play the next weekend and the deck is at 0%. Why doesn’t the deck have a deep sleep or hibernate mode on by default like my laptop or iPad?
Iirc the SD does discharge from full battery a bit when plugged in for a while to preserve battery health.
It will still keep it above 90% all the time which is bad according to most comments I just found by googling about it, it’s just the nature of lithium batteries. Steam deck allegedly has a feature to use direct power from outlet if in use while charging and if at max, but it still keeps battery at high %.
Most of that is really old knowledge from before the days of sophisticated charge controllers.