Lithium Battery Charger Red Light Flashing

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.

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

Bright white light is very bright. Red/red-flashing light is cool -- not sure if I'll ever use it. Good fit and balance (with batteries in back). Lightweight and comfortable. Looks suitably geeky. Very happy with my purchase.

These lithium batteries are very light and last a long time. Charger works well too.

This lithium battery is very reliable.

The Watson NP-BX1 Lithium-Ion Battery Pack and Charger Kit is perfect as a second backup battery. The charger has an easy to see charge indicator light !

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

I keep the Poly-Steel 700 in my truck because of the fact it has the red flashing light on it. If I would have trouble I can just turn it on and stick it to the truck since it also has a magnet. It has the zoom on the front end and all the lights are bright. I have several Coast lights and all of them are high quality and well designed. I will always be a Coast customer. The warranty and customer service is second to none.