Why is Wurkkos FC11 signaling low battery (red) even if the battery is charged?

I have owned the Wurkkos FC11 for a couple of months and it is starting to act weird. Lately is has been signaling low battery level (push button turns red) even if the battery has juice. I have tried several different brands of batteries. The latest one was a new XTAR 18650 3500mAh (10A).

Does anyone have a clue on how I can troubleshoot this issue? Is it fixable? :frowning:

Thanks in advance.

Clean head to body tube threads and tube end contact point to the cap. Screw down with assertion. Typically, poor electrical contacts will give a red signal.

Thanks for the suggestion. :+1:

What cleaning agent do you suggest? Should I lubricate the threads after the cleaning?

Please enjoy your time here, BeautifulStavros!

People here have a fondness for Isopropyl Alcohol (IPA). I use Methyl Hydrate (MeOH – wood alcohol), Sometimes, to get any grease out of the threads, I use MEK (Methyl Ethyl Ketone) or lacquer thinner (which is a concoction of many volatile solvents).

Lube – that’s a rabbit hole. Generally a bit of silicone type grease about the threads. Helps in the screwing down of the end cap. Front end, bare threads (not often opened that end and best conduction). But that depends if the tube sits on a retaining ring, else, the threads do the conduction.

Basically, the conduction path should be free of grease. Sometimes a built-up will interfere with the current and trigger the LVP (Low Voltage Protection).

I hope you are using a quality external charger and not the built in one. Internal ones are flakey.

I hope you are using a quality external charger for your phone and not the built in one. :wink:

Nothing wrong with built-in chargers of most flashlights.

Internal flashlight chargers are plagued with all kinds of problems all of which have been documented on BLF.

Your reference to phone chargers is misleading. If Samsung designed a flashlight and sold it for $1000 , it would likely have a great charger.

Wurrkos and Sofirn etc, not only don’t have the engineering capability to do it, they would be trying to squeeze it into a $20 light.

No comparison between internal and external chargers, for example by Nitecore.

Can I presume the issue was dirty threads?

Firstly, OP new to the flashlight community and unaware of such triviality.
Secondly, as stated, the light worked fine for a few months. On-board charging either works out of the box or is dubious which raises questions from the start. Issues were over-charging (on rare occasions). A newbie wouldn’t know of such if not curious to counter-check with a ‘smart’ charger. Other issues were tail switch activation for charging – doesn’t apply here.

Thirdly, it would be courteous to follow up on either solution found or if a persistent problem.

A few weeks ago, my sister was having the exact same issue with her FC11.
I cleaned all the electrical contact points with alcohol, including both ends of the cell.
It seems to be working properly for her now.

I wouldn’t doubt some lights with internal charging can have issues but being a user of the Fc11 since launch of the updated version with PD usb c - c support, I have only ever charged this flashlight using the internal charging and never once had an issue with it.

I’ve run several lights with internal charging with no issues. They top up to 4.2v and work as necessary. It’s there for convenience, use it.