Quick answer
- On the Kobalt KRC 40-06 (40V Max) charger, a blinking red light means a charging fault. A solid red light is a different thing: the battery is over temperature. The 80V KRC 30-06 and KDC 50-06 chargers use the same light table.
- Blinking green means charging, and solid green means fully charged.
- Try the manual's reset first: remove the battery for 1 minute and reinsert it. If it still blinks red, unplug the charger for 1 minute, plug it back in, and reinsert the battery. If it still blinks red after that, the manual says the battery is defective.
- If the battery is swollen, punctured, or corroded, do not use it. Recycle it.
Symptoms
- The charger shows a blinking red light when you insert the battery.
- The charger shows a solid red light instead, which is over temperature rather than a fault.
- The charger shows no light at all, which points to the outlet or the charger itself.
Quick checks
- Outlet: plug the charger into a working outlet. A dead outlet leaves the charger dark.
- Battery: look for swelling, punctures or corrosion. A damaged battery should not be used.
- Temperature: the KRC 40-06 manual says charging begins once the pack is between 37°F and 117°F (3°C to 47°C). Below 45°F or above 104°F, move the charger and battery somewhere at room temperature.
- Seating: make sure the battery sits fully in the charger.
- Charger: try another compatible Kobalt battery in the same charger to rule out the charger.
Step-by-step fix
-
Read the light. Blinking green is charging, solid green is done, solid red is over temperature, and blinking red is a charging fault (Kobalt KRC 40-06 manual).
-
If it is solid red, let the pack cool in the charger. Charging resumes when it is back in range.
-
If it is blinking red, remove the battery for 1 minute and reinsert it.
-
Still blinking red? Unplug the charger for 1 minute, plug it back in, and reinsert the battery.
-
Check the terminals for dirt or corrosion and wipe them gently with a dry cloth.
-
Test with a second battery. If a different Kobalt pack charges normally, the first one is the likely cause.
-
Replace the battery if it still blinks red after the reset.
If it still isn't working
Check whether the battery is still under warranty, and contact Kobalt customer service. The KRC 40-06 manual gives the charger a 3-year limited warranty. The battery has its own terms, so check its warranty card.
Source
The light meanings, temperature range and reset steps come from the Kobalt KRC 40-06 charger manual (Lowe's, PDF). Other Kobalt chargers, including the 24V models, can differ. Check the manual that came with yours.
FAQ
What does a solid red light mean on my Kobalt charger?
On the KRC 40-06, solid red means the battery is over temperature. It does not mean charging. Charging shows as blinking green, and fully charged shows as solid green.
Can I use my Kobalt charger with other brands of batteries?
No. Kobalt chargers are designed for Kobalt batteries. Use only the packs listed in your charger's manual.
Why won't my battery charge in cold weather?
The KRC 40-06 manual says charging begins once the pack is within 37°F to 117°F (3°C to 47°C). Bring the charger and pack to room temperature and try again.
What should I do if my battery is swollen?
A swollen battery is a safety hazard and should not be used or charged. Swollen or damaged packs are not accepted in most retail drop-off bins. Take it to a household hazardous waste facility.
How can I tell if my charger is faulty?
If it shows a charging fault with several batteries that you know are good, the charger may be defective. Testing it with another compatible Kobalt battery helps confirm this.