18650 3.7 batteries

[1Speedbump]

This is my first post and I'm surprised that this Forum wouldn't let me do a search first for my question. But it wouldn't so...

I have an LED flashlight that I got from renewing my NRA membership. It was a great little flashlight (I know I don't have to tell you guys about LED flashlights) and come with the little 3XAAA batteries adaptor gadget. I don't like this concept. I would much rather have a real battery. So I went on line and bought two 18650 batteries with chargers for $13.00 or so. They turned out to be 68mm long where the triple A adapter is shorter. So are there actually two 18650 batteries that are actually different lengths? And if so, is there a flashlight out there with the high lumen adjustable lens that will accept my two batteries?

Thanks in advance for any advice you can offer.

 

[CreeCrazy]

First off Im not trying to be preachy but you should do some research about charging lithium batteries if you are not familiar with them. Never charge them over 4.2 volts and I never leave the house or go to sleep with batteries on the charger until you completely trust your batteries and charger 100%. Also never let them run completely down. Some 18650 cells have a protective device built on the top of the battery to prevent over and under voltage. The added protection usually makes the cell a little longer. Most 18650 dedicated flashlights will accept the longer cells. There are several great websites to buy 18650 lights. 2 of my favorites are Shiningbeam.com and goinggear.com. They are both here in the US. There are several other great sites too. If you are looking for a cheap light try dx.com. I can't speak for the quality of their lights so try to do some research before buying. Good Luck!!!

 

[shadowjk]

When the protection circuit is added they might go from 65 to 68mm long.

The stickied threads of interest here: http://www.candlepowerforums.com/vb...ronics-Batteries-Included-Threads-of-Interest
Has a link to HKJ's battery test summary thread: http://www.candlepowerforums.com/vb/showthread.php?330236-Battery-test-review-summary
If you scroll down further you'll find a graph of lengths of the tested batteries.

Typically if they start out with a 18650 cells, and add a protection circuit, the length grows a bit.

 

[HKJ]

When the protection circuit is added they might go from 65 to 68mm long.

Both protection circuit and a button top will add to the length.
The longest I have seen is a bit above 70 mm!

 

[Tiresius]

There's two types of 18650 cells you'll come across; protected and unprotected 18650's. Before you look any further, please do some research about safety of them and chargers. It is important you do so to prevent any fatal injuries. Your research will explain about the quality cells vs cheap budget cells of low quality.

Protected cells have a circuit board below the negative side of the battery that is encased with a plastic shell. It protects the cell from current draws, discharge and overcharge rates. They are + 1.8mm-2.2mm in some cases.

Unprotected cells have no circuit protections. They are the ones that usually explodes when users neglect them or leave them charging unattended. If used safely, they're pretty safe.

For your light, it may be possible to accept 18650 cells but it really depends. Some will come with the option of a plastic sleeve for the 18650 to seat in so it won't rattle.

 

[Biker Bear]

The 3-AAA adapters I have are quite a bit shorter than 65mm, assuming the spring mostly compresses - so I went with 18500 size cells and added a spacer (short nut and bolt through a plastic disc) to make up the difference in length. I also found some O-rings that just fit over the cells to reduce rattle, as the 18mm wide cells were noticeably narrower than the 3-AAA adapter. Whether you want to mess about with all this is another question.... *grin*