Can someone help identify this battery?

[CountingCrows]

 

[peter yetman]

Looks like it's 3 x 18550 LiIon cells wired in series and shrink wrapped.
Didn't know they made 18550s but there you are.
P

 

[archimedes]

Looks like it's 3 x 18550 LiIon cells wired in series and shrink wrapped.
Didn't know they made 18550s but there you are.
P

Yes, was thinking the same. Interesting.

Is this in a sort of an odd "triangular" shape ?

It would be helpful if OP might add any other details known.

 

[onemorejolt]

Alibaba has 18550's listed.
They give dimensions as 54.59mm*18.18mm/55.38mm*18.18mm

They look like they may be odd tool batteries, and the search will also pull 18650's with 26650's and 18350's