18650 wont fully charge

[roadkill1109]

I recently bought an 18650 cell and tested its voltage, it was 3.8 volts when i bought it, when i used it in my light and brought it down to about 3.0-3.1 volts i decided to charge it. However, even if I leave it charging for several hours, the voltage never goes up beyond 3.8 volts. Isn't it that fully charged 18650's can go up as high as 4.0 to 4.2? Is there something i'm missing here?

I tried putting the light in my C20C and the red low battery warning comes on, but the battery's not weak it is able to keep the charge for a long time, i've left it on with the low battery blinking now for several hours.

Help? :)

 

[Norm]

What charger and cell do you have?

Norm

 

[roadkill1109]

I use an Ultrafire Charger. The cell is an Ultrafire as well. I tested voltage using a digital voltmeter.

 

[Shadowww]

Nothing surprising, Ultrafire cells are junk.
Get yourself something with brand-named cells inside (Intl-Outdoor batteries, Keeppower, Xtar, Eagletac, AW, Enerpower, or RediLast), and preferably also a good charger (Xtar WP2 II if you don't want to spend much).

 

[roadkill1109]

Nothing surprising, Ultrafire cells are junk.
Get yourself something with brand-named cells inside (Intl-Outdoor batteries, Keeppower, Xtar, Eagletac, AW, Enerpower, or RediLast), and preferably also a good charger (Xtar WP2 II if you don't want to spend much).

Haha! I thought someone would post something like this! Ultrafire cells are a hit-and-miss affair, I was able to buy them for a fraction (1/3) of the lowest price I could find online so i pulled the trigger. The other one I got's working perfectly, so 50% success rate, not bad for a bargain find. :)

I tried completely draining the cell until the battery protection kicked in, left it running overnight in my Crelant V9-T6 and was dead this morning. I have it charging now, if it still wont come up to almost 4 volts, it will be relegated to be used in lights which i use in moonlight mode. Why? Coz the powerful flashlights that detect the low voltage will no longer run in HI or TURBO but somehow the ability of the cell to keep a charge (despite the low voltage) is comparable to a "normal" battery. I left it running all day yesterday, it wasnt until the next day til it died.

Will post updates later in the day.

Cheers!

 

[Lighthouse one]

For you information:

Lion cells like to be recharged often.....don't run them down low on purpose. Low being under 3.25 volts. If you get protected cells...do not try to run them until the protect circuit kicks in....some cells won't recover from that.

I've used Ultrafire for 6 years....I have some that old that still work fine. THe other name brands are no doubt better, but unless you are using your light professionally....they are fine.

 

[roadkill1109]

For you information:

Lion cells like to be recharged often.....don't run them down low on purpose. Low being under 3.25 volts. If you get protected cells...do not try to run them until the protect circuit kicks in....some cells won't recover from that.

I've used Ultrafire for 6 years....I have some that old that still work fine. THe other name brands are no doubt better, but unless you are using your light professionally....they are fine.

Thanks for the info! But isnt it that these Lithium cells are good to only 500 charges? Anyway, when the protection circuit kicked in, the light was dead, but promptly charged for almost the whole day, it just finished charging now and the charger refuses to charge the light. However, one problem: VOLTAGE = 3.77 Volts according to my digital multi-tester! hahaha! I guess the protection circuit kicks in early to cut the charging that is why i get only this voltage! Problem is when i use it in flashlights, it registers as "low batt" so I can't kick it on HIGH or TURBO. My C20C will show the red warning light right away after turning the light on.

So ultrafires can last that long, is that daily use? Coz I use my lights heavy, daily, and so far the batteries that work for me are 2400 protected trusfires (red and black) and my unprotected Panasonic 2900mAh. I also use Trustfire 14500's on my EDC's.

Has anybody here taken out the protection circuit then used the light as an unprotected 18650 cell? Might do the trick so I can charge it up to 4 volts at least.