# Does the 26650 size fit a C cell mag diameter wise?



## john2551 (Feb 17, 2009)

Here is the cell: http://www.batteryspace.com/index.asp?PageAction=VIEWPROD&ProdID=4796

25500 is the exact size of a C cell but are not LiFePO4 safe chemistry: http://www.dealextreme.com/details.dx/sku.5035

I'm not worried about the extra length only the diameter. Would 26mm be too wide? It states *DO NOT remove paper insulator!*


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## Flash_Gordon (Feb 17, 2009)

Those cells are 27.1mm with the cardboard sleeve. That is 1mm larger than a standard alkaline C cell. I think they will fit in a Mag.

Drop some C cells in your Mag and eyeball to see if you have the room. Or take some duct tape and wrap a C cell up to 27mm and do a positive test.

Mark


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## RunningDave (Feb 18, 2009)

I just measured the I.D. of the C-cell Mag and it is exactly 26mm. 

That 25500 cell would fit perfectly if that picture of the digital caliper is precise.


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## john2551 (Feb 18, 2009)

Flash,

I've decided to get the IMR26500 C cells from AW: http://www.cpfmarketplace.com/mp/showthread.php?t=184887 

The length is 50mm & width 26mm, which is the normal C size. These LiFePO4 are 65mm long which are an odd length for me.


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## nicknich22931 (Mar 28, 2009)

john2551 said:


> Here is the cell: http://www.batteryspace.com/index.asp?PageAction=VIEWPROD&ProdID=4796
> 
> 25500 is the exact size of a C cell but are not LiFePO4 safe chemistry: http://www.dealextreme.com/details.dx/sku.5035
> 
> I'm not worried about the extra length only the diameter. Would 26mm be too wide? It states *DO NOT remove paper insulator!*



I purchased some 3200mAh 3.2V 26650 LiFePO4 cells from K2 Energy:

http://store.peakbattery.com/lfp26.html

K2 claims these are 26.2mm dia but the ones I received had cardboard sleeves at 26.7mm and will not fit my C Mag unless I remove the sleeve. 

F.Y.I. I noticed a power tool battery rebuilding service selling GD brand 3000mAh 3.7V 26650 Manganese dioxide (IMR) based Lithium batteries:

http://www.voltmanbatteries.com/servlet/the-3365/26650-BATTERY-REPLACES-A123/Detail

They claim to be 26.4mm dia.


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## Turbo Guy (Mar 28, 2009)

I use 26650 LiFePO4 cells in two MagLights. I removed the cardboard sleeves and applied heatshrink on the cells. They fit fine in my 5C light . Note I only use two of these cells to power a TLE-6EX drop in. You will need 4" (160 mm) heatshrink. Heatshrink will shrink a bunch so 4-1/2 or 180-200 mm will work. A a hair dryer will work to shrink it.

My heat shrinked cells 1.033-1.038" dia. A123System cells with cardboard sleeves 1.060 and they are to big.


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## eebowler (Jun 2, 2012)

Can anyone tell me if the new 4sevens 26650 cells fit in a C size maglite without modification? Thanks.


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## nicknich22931 (Jun 3, 2012)

eebowler said:


> Can anyone tell me if the new 4sevens 26650 cells fit in a C size maglite without modification? Thanks.



*I asked 4sevens the following question:*

"Also, Can you give me the specs as to length and width of the 26650 cells you sell? Since they have a protection circuit they may be too wide and long to fit my lights. As far as I know, you are the only one selling protected 26650 cells."

*their answer:*

"The 26650 is 1.044" D X 2.75" L"

*Note: *1.044" = 26.52mm, 2.75" = ​69.85mm


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## eebowler (Jun 3, 2012)

Thank you nicknich!


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## Swedpat (Jul 23, 2012)

Anyone who tried 26650 in a Mag C yet? I now use it with 3xCR123 in a tube. The tube is exactly 26mm and suits with a very small margin.


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## fivemega (Jul 23, 2012)

*I have never seen any 26xxx fit in unbored M*g "C" but all 25xxx will fit in diameter.*


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## Mr. Nobody (Mar 1, 2016)

How about 2x 18650 on a 2c maglite?
Do I need to go with a 3c for 2 18650s?
How about 2 x 26650 EFEST Red in a 2c maglite?


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## fivemega (Mar 2, 2016)

Mr. Nobody said:


> How about 2x 18650 on a 2c maglite?
> Do I need to go with a 3c for 2 18650s?
> How about 2 x 26650 EFEST Red in a 2c maglite?



*If you are using 2 bare (unprotected) 18650 cells, some modification will be needed but to fit 2 protected 18650 cells in 2C M*g, these or these are vise choice.
All 26xxx cells are too fat to fit inside 2C M*g unless M*g barrel is bored out.
To fit pair of 26650 cells, 3C M*g must be bored out. In this case some extra length can be filled with short dummy or extracted spring or shortening body.*


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## StorminMatt (Mar 6, 2016)

fivemega said:


> *All 26xxx cells are too fat to fit inside 2C M*g unless M*g barrel is bored out.*



Not true. A 26650 will sometimes fit in a C cell Mag. Odds are considerably better if the Mag in question is an old one (no 'C' in serial number) and the cell is unprotected. In particular, King Kongs and A123 Systems cells seem to fit well. I have even fit A123 Systems cells in some newer Mags.


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## fivemega (Mar 6, 2016)

StorminMatt said:


> A 26650 will sometimes fit in a C cell Mag. Odds are considerably better if the Mag in question is an old one (no 'C' in serial number) and the cell is unprotected.


*You are right. Stone aged M*g "C" and "D" barrels are slightly larger in diameter to accommodate some cells.*


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## Overmind (Jan 7, 2019)

There is no 100% certain answer to this, but generally they should fit.

'C' cells are officially *26.2 mm* in diameter.An original 26650 has most of the time 26 or 26.1 mm in diameter, with the plastic casing included.

Now if the outer casing of some models is too thick it will indeed not fit, but such a case is relatively rate.

A similar issue I encountered with some Candian-made 18650s, which were just .1 mm thicker without the plastic envelope and with that they would fit with some difficulty in some devices.


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## alpg88 (Jan 7, 2019)

depends on a cell, but those that i tried, none of them fit, only bored out C mag takes 26xxx cells. however amount needed to be removed is little, people use brake cylinder hones to bore out c mags, just have to do it slow, or you'll clog stones pretty quick.


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## StorminMatt (Jan 7, 2019)

How old is the Mag? Also, are you trying to use protected cells?


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## carl (Oct 15, 2020)

1) Are 2x26650 too long to fit in a Maglite 2C? Can the tailcap spring be shortened to make it fit? 

2) If 2x26500 is the best choice for a Maglite 2C, which 26500 rechargeable battery is reasonably priced and decent quality? Shoshine?

3) If 2x26650 is used in a Maglite 3C, is a spacer required to fill the 10mm gap in the battery tube or will the tailcap spring make up the difference? 

As an aside, IMHO the best setup for battery power is a Maglite 3C with 2x21700 batteries as far as I can tell. But will a Maglite C tailcap spring mate up properly with the end of a smaller diameter 21700 battery?


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## fivemega (Oct 15, 2020)

carl said:


> 1) Are 2x26650 too long to fit in a Maglite 2C? Can the tailcap spring be shortened to make it fit?


*Each primary "C" cell is about 50mm long but protected 26650 is about 70mm long. So in order to fit two of them in bored out M*g 2C you will need either 40mm extender or use bored out M*g 3C with 10mm dummy.*
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carl said:


> 2) If 2x26500 is the best choice for a Maglite 2C, which 26500 rechargeable battery is reasonably priced and decent quality? Shoshine?


*Some extension tube with pair of 21700 is the best choice.*
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carl said:


> 3) If 2x26650 is used in a Maglite 3C, is a spacer required to fill the 10mm gap in the battery tube or will the tailcap spring make up the difference?


*Tail spring will work with less pressure.*
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carl said:


> 4) As an aside, IMHO the best setup for battery power is a Maglite 3C with 2x21700 batteries as far as I can tell. But will a Maglite C tailcap spring mate up properly with the end of a smaller diameter 21700 battery?


*If battery and spring both are centered, no problem.
BTW, possible to use pair of protected 21700 with 26~30mm extension if tail cap is bored out and recessed spring.
This way part of battery will fit inside tail cap and overal length will be minimum.*


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## fivemega (Oct 16, 2020)

StorminMatt said:


> Not true. A 26650 will sometimes fit in a C cell Mag.





RunningDave said:


> I just measured the I.D. of the C-cell Mag and it is exactly 26mm.


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## carl (Oct 16, 2020)

Thank you Fivemega for the great info! Thank you for contributing to our CPF community with all your special manufactured parts/lights and advice to everybody over the years! Much appreciated.


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