18650 battries confused

[Programmergeek]

I have a Fenix light that uses 2 cr123 cells. I just needed more battries so it was sugested I buy the 18650 battries instead which are 2 cr123 cells together so I did I boutght the charger and 4 ultra fire 18650 3000mah battries but they do not fit into the light they are to wide??? Did I get the wrong battreay will 18650 not fit my light or are there different ones?

 

[slappomatt]

the 18650 cells are 18mm X650mm long. (well some are a tad longer...) and the CR123 cells closer to 17mm. some of the flashlights will fit a 18mm cell but alot wont. The cells that you want are the protected 17670 cells. they are 17mm wide and 670mm long. but they dont last near as long as the 18mm ones.

some people buy aftermarket boddies or bore out there own bodies to fit the 18650 cells.

The other issues are that a li-ion battery's are mostly all 3.7V and your 2 CR123's add up to 6 volts. so you need a head/bulb combo that is ok with less voltage.

 

[HKJ]

I have a Fenix light that uses 2 cr123 cells. I just needed more battries so it was sugested I buy the 18650 battries instead which are 2 cr123 cells together so I did I boutght the charger and 4 ultra fire 18650 3000mah battries but they do not fit into the light they are to wide??? Did I get the wrong battreay will 18650 not fit my light or are there different ones?

The name/number of LiIon batteries is composed of diameter and length, i.e. 18650 is diameter=18mm (usual around 18.5mm), length=65mm (Usual around 68mm for protected batteries).

CR123 batteries are 16340 in size (Also called RCR123), i.e. they are only about 16mm in diameter.

Next problem is voltage, a single LiIon battery is around 3.7 volt when used (it is 4.2 volt off the charger), this is a rather low voltage for a 2xCR123 light (6 volt), except if it is designed for it.

Depending on what Fenix light it is, you might be able to use two 16340/RCR123 batteries or a 17650/17670 battery.

 

[Mjolnir]

Which fenix light do you have? Only a few of their 2 CR123 models will physically fit an 18650 cell (like the TK10 and TK11).

You have been misinformed about the batteries... An 18650 is in no way 2 CR123s together; it is simply a similar length to 2 CR123s (but a little wider). It also has a nominal voltage of 3.7 volts, while 2 CR123 cells are around 6 volts. This means that a light not specifically designed to run both kinds of cells will dim more with an 18650.

17670 rechargeable cells (which are a little longer and a little thinner than 18650s) may fit in your light, but they might not give it full output.

EDIT: Wow, 3 responses in the same minute...
And, we all said virtually the exact same thing! CPF has us trained well...

 

[T0RN4D0]

Yep you got your answers, just want to point out that the batteries are of course not 650mm long (slap yourself slappomatt ), but as HKJ stated 65mm. :]

 

[DM51]

Wrong forum... moving to Batteries...