Hart 40v Battery Not Charging Red Light Flashing

Quick answer

• On the HART HLCG01 40V charger, a flashing red light means the battery is too hot or too cold. Charging starts once the pack reaches a suitable temperature.
• Red with two quick blinks means a pack or charger error. Reseat the pack, then try a different pack.
• A solid red light means the charger is plugged in with no battery installed. It does not mean charging. Solid green means charging is complete.
• The meanings above come from the HLCG01 manual. Other HART 40V chargers may differ, so check the manual for yours.
• If the battery is swollen or damaged, do not charge it. Replace it.

Symptoms

• The charger shows a flashing red light when you insert the battery.
• The charger shows red with two quick blinks, which is an error rather than a temperature hold.
• The charger shows a solid red light with no battery in it. That is normal standby.
• The battery will not power your tool.

Quick checks

1. Temperature: a flashing red light on the HLCG01 means the pack is hot or cold. Let it sit at room temperature and see whether charging starts.
2. Charger: confirm you are using the HART charger made for 40V packs. Look for damage or debris in the charging port.
3. Battery condition: look for swelling, corrosion or physical damage. A damaged battery should be recycled and replaced.
4. Seating: make sure the pack is fully seated and the contacts are clean.
5. Outlet: plug the charger into a working outlet.

Step-by-step fix

1. Remove the battery from the charger or tool.

2. Inspect it for swelling, corrosion or damage. If you find any, do not charge it.

3. Check the charger. With no battery installed, a solid red light means the charger has power. If it shows nothing, try another outlet.

4. If it flashes red, bring the battery and charger to room temperature and reinsert the pack. On the HLCG01, charging starts once the pack is in range.

5. If it shows red with two quick blinks, remove the pack, reseat it, and retry. Then try a different 40V pack to see whether the first pack or the charger is at fault.

6. Clean the contacts with a soft, dry cloth.

7. Replace the battery if it still will not charge.

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If it still isn't working

• Warranty: check the terms for your Hart battery and charger, then contact HART customer service or the retailer you bought it from.
• Replacement: if the battery is out of warranty and will not charge, replacing it is usually the practical choice.

Source

The light meanings above come from the HART HLCG01 40V charger operator's manual, as reproduced on ManualsLib, which is not an official HART site. Other HART 40V chargers, such as dual-port models, may use different patterns.

FAQ

Why is my Hart 40V battery flashing red?
On the HLCG01 charger, flashing red means the pack is too hot or too cold. Wait for it to reach a suitable temperature. Red with two quick blinks is an error.

Can I charge my battery if it's cold?
Most lithium-ion batteries will not charge when they are too cold. Warm the pack to room temperature first. The charger's manual sets the exact range.

What should I do if my charger is not working?
Test it with another compatible 40V battery. If it still shows nothing, or an error, with a pack you know is good, the charger may need replacing.

How can I tell if my battery is damaged?
Look for swelling, corrosion or physical damage. If you see any, do not use it. Recycle it properly.

Is it safe to use a damaged battery?
No. Damaged batteries can pose safety risks. Recycle them and replace them with new ones.