Dewalt Battery Charger Light Flashing Fast

As many others mentioned in the reviews, these batteries are now new old stock, as the newest ones were made in 2022 and will arrive completely discharged. DO NOT give up on them - the charger will initially show an error (chamber and calibration light flashing) - keep taking the battery off and putting it back on, and eventually it will start to charge. The key is to not leave it in the charger if the charger is showing the error code, you have to remove and replace the battery until the charger shows that it is charging (chamber light and 50% light flashing). After a few hours the 50% light should glow solid and 80% should start flashing, and eventually it will charge fully

A perfect fit for my spare DeWalt 20V, 5Ah battery.

This is a very nice headlamp, without two levels of white light, a red light and a flashing red light.  Having the battery pack on the back makes it much easier to balance and the straps are adjustable over a wide range.

My APC UPS sounded off every few hours with beeps and a flashing red light to let me know it was time to replace the battery. I ordered online and the battery arrived sooner than expected. I installed it and it's been working fine since. The part I especially like, I didn't have to shut everything off to install.

I bought this a month ago when the battery died (I unfortunately did not notice the low battery flashing light indicator). The replacement battery arrived very promptly, was easy to install, and my backup is operational again — and just in time because a tornado hit here a few days later and I lost power for 8 hours.

but it is unsettling to have the upstream light flashing

Very good device but hardly fast speed and external light keep flashing green. But over all everything seem fine

Shipping was very fast. the battery charger is great.

Nice charger. Easy to use. Charges battery fast.

Great charger, it charged my battery just as fast as the Nikon charger.