Hilti Battery Charger Light Meanings: Blinking Green and Charging Problems

Quick answer

• Hilti charger lights vary by model. Check the legend on the charger body or in its operating instructions before assuming a fault.
• The Hilti C 4/36 operating instructions describe a green charger LED, not a red one. Steady green with the battery LEDs blinking means charging. Blinking green means the pack is too hot or too cold. Steady green with no battery LED lit means a defective battery.
• If your charger shows a red light, it is a different model, so use that model's manual.
• Let a hot or cold pack reach room temperature and try again before assuming it is defective.
• If the battery is swollen, punctured, or corroded, do not charge it.

Symptoms

• The charger light is blinking in a pattern that does not match "charging" or "charge complete" on its legend.
• On a C 4/36, blinking green appears when the pack is outside its acceptable charging temperature range.
• The pack feels unusually warm or cold.
• The charger does not start a charge cycle at all.

Quick checks

1. Battery temperature: if the pack feels hot or cold, let it reach room temperature before charging.
2. Connection: plug the charger into a working outlet. Test the outlet with another device if needed.
3. Battery condition: look for swelling, punctures, or corrosion.
4. Charger model: confirm your charger model (for example the C 4/36) and check its operating instructions for the LED legend.
5. Compatibility: use the battery the charger is made for. Check the charger and battery labels.

Step-by-step fix

1. Remove the battery from the charger.
2. Read the light against the manual. On the Hilti C 4/36, per the operating instructions, steady green with blinking battery LEDs is charging, blinking green is a pack that is too hot or too cold, and steady green with no battery LED lit points to a defective battery.
3. Inspect the battery. A swollen or corroded pack must not be used.
4. Let it reach room temperature and reinsert it. If the light still shows a problem after the pack has equalized, the fault is persistent.
5. Reconnect the charger and watch the LEDs.
6. Try a different Hilti charger, if you can, to find out whether the charger or the battery is at fault.

If the battery is in good condition but still will not charge, consider replacing it.

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If it still isn't working

• Warranty and service: Hilti offers a Lifetime Service program on many tools, with a defined no-cost repair period followed by cost-capped repairs. Review the terms for your charger and battery, and contact Hilti or a Hilti Center for a test of a pack you suspect is defective.
• Replacement: if the battery or charger is beyond repair, buy a new unit and confirm it is compatible with your tools.

FAQ

What do the lights on a Hilti C 4/36 charger mean?
Per its operating instructions: steady green with blinking battery LEDs is charging; blinking green is a pack that is too hot or too cold; and steady green with no battery LED lit points to a defective battery. A red light is not described for this charger.

Can I charge a cold battery?
A pack outside the charger's allowed temperature range will not charge. Let it reach room temperature, and see the operating instructions for the exact limits.

How do I know if my battery is defective?
If it still will not charge at room temperature, and the charger works with another pack, it may be defective. Have it tested at a Hilti Center.

What should I do with a damaged battery?
Do not use or charge it. Swollen or damaged lithium-ion packs are not accepted in most retail drop-off bins. Take it to a household hazardous waste facility or follow the damaged-battery procedure from Call2Recycle.

Is there a way to reset the charger?
Most chargers do not have a reset function. If the charger keeps showing a fault with a good battery, it may need servicing or replacement.