To be clear, battery life and battery health are different things. Life is how long it can run before 0%, and health is how good of a condition the battery is in.
AFTER A YEAR AND A HALF, MY STEAM DECK BATTERY HEALTH IS 90%; APPARENTLY THAT’S GOOD, BUT I NEED LEARN TO NOT LET IT GO UNDER 20% BATTERY CAPACITY AND ALSO SHUT IT OFF WHEN I’M NOT GAMING FOR A WHILE RATHER THAN PUTTING IT IN SLEEP MODE.