Symptoms
- Charger's indicator light stays off when the battery is inserted
- Charger cycles or resets repeatedly without starting a charge
- Battery seems seated but doesn't trigger the charger
- Works with one battery but not another of the same type
Likely causes
- CommonBattery inserted in the wrong orientationReversed polarity prevents most smart chargers from starting, as a safety feature.
- CommonDirty or corroded contacts on the battery or chargerA thin film of oxidation can block the electrical connection needed for detection.
- PossibleBattery voltage too low for the charger to recognize itSome smart chargers won't detect a battery that's discharged below a certain threshold.
- PossibleWrong battery chemistry or size for that chargerChargers designed for one battery type may not recognize an incompatible one.
- Less commonCharger slot or contacts are damagedPhysical damage to the charger itself can prevent any battery from being detected.
What to do
- Double-check the battery is inserted in the correct orientation, matching the polarity markings.
- Wipe both the battery terminals and the charger's contact points with a dry cloth or a cotton swab.
- Confirm the battery type and size match what the charger is designed for.
- Try a different, known-good battery of the same type to see if the charger detects it.
- If no battery is detected, and contacts look clean and correctly oriented, the charger itself is likely faulty.
Tools and parts
- Dry cloth or cotton swab
Replacement battery chargerSearch: “rechargeable battery charger replacement”
When to call a pro
No professional repair applies; replace the charger if a known-good battery still isn't detected.
Safety
Generally low risk
Generally low risk for a careful person. Stop if anything looks different from what this guide describes.