18650 size

[DE73]

The 18650 gets bigger and bigger and doesn’t fit in al lights. It should be very good with a thread where we can share measurements. I have a couple of times bought batteries that have to large diameter for the light.
I’m about to buy some new 18650 and are interested in diameters for high capacity Keeppower (3500 and 4000mAh)
Please measure at different places and share biggest diameter.

 

[DE73]

Olight 3400mAh
Diameter 18,5mm
Bought year 2022

 

[aznsx]

I know little/nothing about the physical construction / dimensions of 18650 cells.

What I do know is that many protected 18650 cells have a bus bar / flat conductor that runs up the side under the wrapper which provides an external electrical connection between the physical ends of the cell, and that likely means increased diameter which is not constant (is out-of-round).

Photos in this article illustrate this:

https://lygte-info.dk/info/battery protection UK.html
I also know there are some protected cells which apparently don't use this design, and here's an example of one which is advertised as not having such a 'bus bar', which would result is a slightly smaller max diameter which is more 'round'. I have a couple of these and they're good cells (EDIT: with very low DCIR). My calipers are inaccessible at this time, so I cannot measure anything.

https://illuminationgear.com/shop/ols/products/18650-3600mah-eagtac-battery
The description includes this text:

"Brass button top contact with PTC/Protection circuitry now at "top" of battery (with steel plate used at bottom for added durability).
By moving PTC to top ~ reduced stresses are placed on the IC components for increased reliability. This design also creates shorter battery length, and no metal strip running along side of body for safer use ~ narrower width. All internal connection is made using pure nickel for better conductivity."

As with most things, there are tradeoffs. You may need to prioritize your requirements / criteria, and if diameter is critical to your application, you may find that means you may limit your possible cells to choose from. It is often impossible to optimize for all your requirements in the same cell. There are usually choices to be made.

Such is life in general;-)

 

[jonc2]

I'm interested in lengths also which is important, especially protected/unprotected.

 

[aznsx]

I'm interested in lengths also which is important, especially protected/unprotected.

I hear ya! I have some 1x16340 lights that I use daily, and I struggled to find a good, protected cell to fit in them properly w/o spring over-compression / bottoming, etc. (ET D25C in particular).

Just as an aside, although I don't have my calipers here, I can easily tell that the 18650 I linked to above is clearly, visibly shorter than either the Fenix or Streamlight cells standing next to it here on the table beside me.

 

[DE73]

I'm interested in lengths also which is important, especially protected/unprotected.

Be careful if you measure the length with caliper. Risk to short circuit the battery.

 

[jonc2]

Be careful if you measure the length with caliper. Risk to short circuit the battery.

Great advice!

I hear ya! I have some 1x16340 lights that I use daily, and I struggled to find a good, protected cell to fit in them properly w/o spring over-compression / bottoming, etc. (ET D25C in particular).

Just as an aside, although I don't have my calipers here, I can easily tell that the 18650 I linked to above is clearly, visibly shorter than either the Fenix or Streamlight cells standing next to it here on the table beside me.

I'm wanting to try out SureFire's 18650 with USB C charging, they are a bit longer than the protected KeepPowers I'm running in my Malkoffs (with spacer).

 

[DE73]

Great advice!



I'm wanting to try out SureFire's 18650 with USB C charging, they are a bit longer than the protected KeepPowers I'm running in my Malkoffs (with spacer).

What Keeppower do you have? Can you measure diameter? If you buy Surefire please measure.

 

[jonc2]

What Keeppower do you have? Can you measure diameter? If you buy Surefire please measure.

I'm using 18650 KeepPowers. I don't have an accurate way to measure the diameter and I haven't purchased the Surefires yet.

 

[Galane]

There are plastic or composite jaw digital calipers for safely measuring the length of batteries. Or you could just put pieces of tape on the jaws and hit the zero button.