From what i’ve read this is pretty typical for 10180 batteries (and other very small/high resistance/low capacity batteries). I doubt you will ever get a 10180 to 4.2v and maintain it for any length of time on a built in charger.
Built in charger??? This is a USB light
It does NOT have to be 4.20V. If the USB charged it to 4.15v that would be acceptable.
So a FULL charge of 3.99V is acceptable to you?! Sorry,the battery has to be old and degraded to have 3.99V as a full charge. 
Yeah, 3.99V would be slightly over 50% on these tiny cells. I have a couple of those blue, no name 10180 cells and they read 4.15V after charging.
I’m not saying it’s acceptable but in practice/reality this is pretty common I think. 10180 batteries aren’t known for being super high quality in the first place then you rely on a charger which may not even have a low enough charge rate to get right up to 4.2V consistently.
I’m only relaying what i’ve read during my own research looking for a good keychain light, i’m no expert.
I’m actually dealing with a bad 10440 from Liion right now and as you know they are pretty reputable. Truth is these small batteries, are not.
You keep mentioning chargers. This is a USB FLASHLIGHT. Charged through my computer/tablet ect.
Liionwholesale will take care of you, Jon is my neighbor and that is where I get all my batteries. No shipping,I just have to go 1.5 miles to the warehouse.
Whatever the issue, I guarantee he will make it right.
Well, I received my light yesterday. The included battery wouldn’t operate the light so I proceeded to charge it using the built-in charger in the light.
I waited about 2 hours and the red charging light wouldn’t go out. I removed the battery and tested it and it only read 3.7V which is only around 25% capacity.
I thought it was a defective cell but on a whim, I decided to try and charge it on a charger I have that safely charges 10180 cells. After about 45 minutes or less, the light went off in my charger indicating the charging was complete. I tested the cell and now it read 4.18V and put it back in the light and it now works as advertised.
So, I have a light that works but the built-in charger is defective. I sent an e-mail to B.J. explaining this and we’ll see what they have to say.
Hey wolfdog, maybe the charger in your light is defective also and that’s why it would only charge your cell to 3.99V.
By the way, how would the built-in charger work anyway? When you unscrew the body to expose the charging port, the light is on. Does the light turn off when connected to a power source while charging?
Well it’s now Thanksgiving so HAPPY THANKSGIVING to all!
Looks very interesting at this sale price and I will purchase one along with the klarus battery as backup. Is it possible to turn this light on/off with a single hand?
Yes, it turns on/off fairly easily with one hand. I lubed the threads and head gasket to make it even easier. You have to be careful screwing the head back on after removal as the head gasket can easily get caught on the threads of the head and get chewed up.
One of the things I like about this “twisty” light is you tighten the head all the way down to turn it off. Almost all twisty lights turn off when you loosen the head. No chance of accidental activation.
I e-mailed BJ about the light’s built-in charger being defective. They responded by saying they would send me an RMA to send it in for repair. No way I’m going through all that hassle on a $18.00 light.
I told them I’d be happy with a partial refund. We’ll see what they say. Except for the built-in charger being defective, it functions perfectly and the included 10180 cell charges up fine using a charger I have and it’s not a big hassle to just remove the cell and charge it externally. I like the beam and the 88 lumens are plenty for a light this size.
Thanks for the update. I will order one on the hope same would have a working charger.
Just an update but Battery Junction offered a $6.00 partial refund which I accepted. The light works great and it’s no hassle to me to remove the cell from the light to charge it.
I wish the built-in charger worked and if I had paid full retail, it would have gone back but for $12.00, even with the defective charger, it’s still a pretty neat little light.
Glad to hear you received a discount. I have another light that uses this same type of battery, but same is a blue no name battery and I notice it only goes up to 3.98 after the built in charger stops. Just a couple days later with no use at all the voltage reads 3.72. Upon reading the above comments I understand something is not right. Could it mean the built in charger is not working properly or that the battery is defective? What type of external charger for these small batteries are you using?
damn… missed the discount on this one!
I have several 10180 cells and they are no name blue and white cells with the blue being the most prevalent. They both work equally well.
I have two methods of charging 10180 cells. I have a basic 100ma Cottonpickers charger. A lot of folks say 100ma is too much for 10180 cells and could reduce the number of charges but I’ve used it many times on my cells and they always reads 4.18-4.2 after the charge is complete. Cottonpicker himself who builds them told me 100ma may reduce the number of charges but it would be insignificant.
I believe Cottonpickers chargers are still available over on CPF and the basic 100ma charger is very reasonable.
The other method I use is I have a couple of DQG 10180 lights and bought one of the DQG mini chargers that screws onto the head after the LED head is removed, (around $10.00). You pop the cell into the body and screw the charger head on. The LED light glows red and turns green when charging is done same as the Cottonpicker charger. It charges at a lower 50ma and works well but takes longer. The only problem is you have to have a DQG body to use it.
I firmly believe that a lot of the built-in chargers in these lights are defective which is why TDL, wolfdog and myself are having problems. Maybe that’s why they were selling at half price?
So for those who bought this light, how do you find it compares to other 10180 lights around? Namely those ones that are made up of three pieces (instead of 2 pieces in the comet)? I have one a mecarmy 10180, but sometimes the various pieces get loose because of overturning them.
Actually, because the built-in charger doesn’t work, it still breaks down into 3 pieces to get the 10180 cell out for charging. Inside there’s a metal sleeve that holds the cell in and you have to unscrew it and take it off to remove the cell.
This could be smaller if it didn’t contain the built-in charger but the slightly larger size makes it easy to operate one handed. The head turns very smoothly.
Again, like I mentioned earlier, I really like that you turn this off by turning the head all the way tight or clockwise to turn it off. To me, it’s a nice feature to avoid accidental activation. I wish all twisty lights were like this.
Why doesn’t the built in charger work? All units have this problem or is it just yours that is faulty? With the other 10180 variants, if you over tighten the light to turn it on, it actually loosens the tail cap. The comet doesn’t have this issue does it?
hazna, read the posts above and who knows why the built-in chargers don’t work? If you have an idea, please let us know. It seems like some folks are having problems. They work, (sort of), but don’t charge the cell to anywhere near full capacity and to me, that’s fully defective.
There is no tailcap on this light. Anyway, this was an interesting thread but I’m done with it. Thanks to all.
By the way hazna, your blog is very professional looking.
I sent mine back and got a FULL refund.I told them about the battery and she did not want to hear it. She thought a full charge was 3.7V!!! I had to explain the voltages to her.
Anyway,I won an Olight S1 mini that comes tomorrow. A superior light to this comet and only 0.3” longer.
Sorry, I had a quick browse through this thread beforehand. I was under the impression the issues was the batteries included with the light, rather than the charging function itself. Having a more thorough read through your posts, it seems you have and issues with the charging function.
That might be one of the reasons why they were selling these lights so cheap. Probably a bad batch. It would be pretty bad if you had paid ~$50 for it and have issues.
I have been EDCing the light I purchased from battery junction and here are my comments. It is not available any longer at BJ but it is still available in other places via online as I have found out but of course with the regular prices similar to other titanium lights so I believe BJ just wanted to get rid of the inventory. The light is better than expected. It is of high quality both the exterior and the interior components, so it was an excellent purchase at that discount and I do not regret same at all as it is well built like a tank, it is highly polished and thus I would expect to last me many years. It has a pleasant cool light tint but I do not see too much of a difference on both outputs, that is the low should be much lower but I could live with that. The head rotates smoothly despite being a titanium item and could be operated with a single hand, a factor very important to me in EDC items. I also like that it turns off by tighting the head. It has no yet turned on by itself. Anyways, most important of all it provides plenty of lumens for the intended use I give them. I carry same in my neck with the lanyard provided. Due to its construction it is rather heavy and long in comparison with the other similar lights but strangely enought I do not feel an unconfortable weight or bulky item under my shirt. Regarding the built-in charger I see I was lucky then with my unit as mine works reasonably fine as it charges battery up to 4.12V, which is a 98% charge. My other charger did not pass 4V as previously commented so I understand it does not work like it should. All my other batteries of this size 10180 dont pass this voltage of 4.12 even a Klarus one I purchased at BJ at the same time just as a test and it is the one I am using with this light given I see it is also of quality. I am not clear yet if it is really the chargers or the batteries but I do not lose sleep on that 2% missing. I am now kind of liking these tiny lights for what they output given their sizes and weights and I ordered a few days ago at bestgear the DQG spy in brass version which is the tiniest one I found at just over one inch long and also with a separate charger to see how I go with this combination. Perhaps these tiny batteries are the ones that need further developments and controls. I see Fenix sell one for their flashlight which is protected but since it is longer due to the IC perhaps it would not fit the casing of this light. Anyways I may give a try one of these days to see what happens