If you keep it plugged I all the time, there’s a Decky Loader plugin called Powertools that has a handy charge limit for the battery. For a Deck you take places, limiting it to 80% is a good compromise that will increase battery life. For a Deck you leave plugged in all the time, I would recommend to set the limit to 50-60%, which is a good “resting” charge that doesn’t put any stress on the battery from being too drained or too full.