Danielle Bell

Classic sag under load. That drop from full bars at rest to one bar the moment you pull the trigger is what lithium packs do when internal resistance climbs and the cells are cold or a bit tired. Stored cold in a garage the chemistry is sluggish and the weakest cell dips hardest, so the protection board cuts out even though the indicator looked fine sitting still. Warm the battery to room temp before you use it and before you charge it. After it is warm, charge to full again so the balancer has a chance to finish, let it sit for a short rest, then try the drill. Give the tool a gentle no load spin for twenty to thirty seconds to warm the cells from the inside. Use the low gear for screws and predrill so you are not hammering the pack with spikes. For storage longer than a few weeks, park them around half charge and top up the day you work. Two mild cycles where you charge to full, run light work until the first slowdown, and recharge can straighten out the gauge. To separate battery from tool issues, test with a warm pack and no bit. It should sound smooth with no gritty notes and it should coast down instead of stopping abruptly. Any roughness or a hot smell suggests gearbox or chuck drag that is pulling extra current. If a borrowed warm battery from the same system runs your drill normally, your packs are the culprit. If every pack sags the same way even warm, try charging the warmed pack twice back to back to encourage cell balancing, and consider that the drill may have developed extra drag that needs service.