25950 cell?

[capsicum]

Just wondering if anybody knows of an engineering reason why we don't see approx double length LiFePO4 cells in the standard letter diameters.
It seems like they would make great drop in upgrades to anything that uses 2 or 4 cells. All those 2AA, 2C, and 2D flashlights out there could have 14950, 26950(-1+0 dia tolerance), and 32115. 3.2v and huge capacity. I undersized the length 5mm to allow for cell protection where desired and still fit tight designs. Maybe an idea 10 years late.

 

[capsicum]

So there are Double-C cells on the market! So far all I have found are primary lithium, they are marketed for drilling rig sonde transmitters.

Digitrak-supercell:
Voltage: 3.6 Volts
Capacity: 17000mAh
Chemistry: Lithium
Dimensions: Diameter 26.2mm x Height 102.0mm

 

[Juggernaut]

There are 10900 cells I found about the other day (double AAA) which is really cool.

 

[fivemega]

why we don't see approx double length LiFePO4 cells in the standard letter diameters.

There must be high quantity demand for such a battery to be made.
Any battery company will be happy to make 10,000 units of each size for you and if you make 3.7 Volt Li-Ion type, I will buy few of each size.