DIAGNOSIS This is almost always a failing battery, not the drill. The battery cells can't deliver the high current needed under load, even if they show full charge.
FIX Test with a known-good, different Makita 18V LXT battery. If performance is normal with the other battery, your original battery is the problem. For the weak battery:
- Fully discharge it by running the drill (no load) until it stops.
- Then charge it fully on the standard charger (not rapid). This can recalibrate the battery's management system.
IF THAT DIDN'T WORK The drill's motor or controller might be overheating and reducing power to protect itself. Let it cool down completely for 30 minutes and retest. If still weak with a good battery, internal electronic damage is likely.
HEADS UP Using aftermarket or physically damaged batteries is a primary cause of this. They often can't meet the drill's peak 30A+ current draw, causing immediate power sag.