How many C cells/25500’s fit into a 6D Maglite with short spring?
Really hopping for 9 C cells for a Hotwire build I have in mind
Inside of a 6D maglite is 37cm to the threads
so we could say 36 / 5 = 7.2 
How about using the 26350 (if they exist) now you are over 10 cells you will need a spacer cell to get it down to 9.
35 / 3.5 = 10, stock spring and placement. (+copper braid of course)
or even 32350 size (if they exist)
I want to provide 36V input
9 x 25500
26350’s where are those?
It looks like we are not alone in wanting 26350 cells
I guess if push comes ot shove you can go with 18350 cells
I bet something like this would be too long.
http://www.aliexpress.com/item/3-2V-high-quality-36250-cylindrical-power-Lifepo4-lithium-rechargeable-electric-vehicle-battery-with-5000mAh-capacity/2038059171.html
excellent find but I think it is a typo:
“Battery type :3.2V lithium ion Lifepo4 32650 cell”
Dunno what kind of current draw you need, but for batteries you have some other options as well. Tandem 16650’s should fit, and 17650’s may fit in a mag tube without requiring any boring, in 10s arrangement. A 36v bulb can generally handle 42 volts. 42-30v operation over the run sounds pretty good.
Another option would be 14500’s in 9s2p but you’re only going to get some 1.4Ah capacity and 6A 13A delivery with IMR’s. I can build pretty much any arrangement of battery holder. They feature 4oz copper and plated BeCu springs. This is an early 3s2p holder; a functional prototype so nevermind the soldering and lack of insulation:
