Symptoms
- Charger indicator shows complete/green light
- Drill still runs out of power within minutes of use
- Problem is consistent across multiple charge cycles
- Other batteries in the same tool perform normally
Likely causes
- CommonBattery cells have degraded and can't sustain a load even though voltage reads full at restA battery can show a full voltage reading while having lost much of its actual usable capacity under real work.
- CommonCharger's 'full' indicator is based on voltage/time, not true capacity testingBasic chargers estimate full charge rather than measuring true remaining capacity.
- PossibleOne weak cell in a multi-cell pack dragging down overall performanceA single bad cell can cause the whole pack to cut out early even if others are fine.
- Less commonBattery contacts making poor contact under vibration during useThis can cause intermittent dropouts that feel like the battery is dying fast.
What to do
- Compare the questionable battery's runtime directly against another battery of the same type on the same task.
- Check that battery contacts are clean and make firm contact, ruling out a connection issue rather than true capacity loss.
- Test the battery across a few charge cycles to see if performance is consistently poor rather than a one-off.
- Note the age of the battery, since a pack that's more than a couple of years old showing this symptom is a strong sign of normal wear-out.
- If the pattern is consistent and other batteries are fine, this battery has lost usable capacity and needs replacement.
- There's no way to restore lost lithium-ion capacity; reconditioning tricks don't meaningfully work on modern power tool batteries.
Tools and parts
Replacement cordless drill batterySearch: “cordless drill replacement battery pack”
Safety
Generally low risk
Generally low risk for a careful person. Stop if anything looks different from what this guide describes.