Symptoms
- No light when pressing the button
- Light comes on then shuts off after a few seconds
- Mode button cycles through settings on its own
- Headlamp works when squeezed or tapped but not otherwise
Likely causes
- CommonDead or weak batteriesHeadlamps are often used intermittently and batteries drain or self-discharge between trips.
- CommonCorroded battery contacts from sweat or humidityHead straps put the battery compartment close to sweat and moisture.
- PossibleBattery compartment door not sealing, letting in moistureA worn gasket lets water or sweat reach the contacts.
- PossibleStuck or worn mode buttonFrequent use in the field can wear out the rubber button seal.
- Less commonLow-battery auto-shutoff feature (on some models) mistaken for a faultSome headlamps deliberately cut power at very low battery to protect cells.
What to do
- Remove batteries and check contacts for corrosion, cleaning with a cotton swab and a little vinegar if needed, then drying fully.
- Test with a completely fresh set of batteries of the correct size and type.
- Check the battery door's rubber gasket for tears or a poor seal if the headlamp has been used in rain or heavy sweat.
- Press the mode button firmly and repeatedly to see if it's sticking; clean around it with a dry cloth or soft brush.
- If it shuts off under light pressure or vibration, suspect a loose internal connection, which usually isn't user-repairable.
- Store headlamps with batteries removed between long periods of non-use to prevent corrosion and slow drain.
Tools and parts
- Cotton swabs
- Vinegar
- Soft brush
Correct battery sizeSearch: “headlamp replacement batteries (check manual for size)”
When to call a pro
Many headlamp brands offer warranty replacement for internal faults; check the manufacturer before buying a new one.
Safety
Generally low risk
Generally low risk for a careful person. Stop if anything looks different from what this guide describes.