Finding cells in smallish quantity isn't really an issue.
The current popularity of e-cigarettes or "vaping" has very much broadened
the "corner store" availability.
Ordered a mixed dozen or so off Amazon a couple weeks ago.
Finding cells with solder tabs is a fair bit trickier.
Finding known reliable supply chain seems to add another dimension.

Initial testing of three different cells from three different Amazon
sellers shows that specifications are subject to outright lies.
Some rated 2400mAh measured pretty much 2400mAh,
Some rated 3000mAh measured about 900mAh.
Some fall off massively at over 1A discharge rate.
Some handle 10A without issue.

The next major hurdle I ran into seems to be holding the cells.
I started with cheapo holders with a conical spring in the bottom. It took
me a bit of testing to realize I was loosing nearly a volt at the contacts
at a 4 amp draw.
I moved on to "better" holders (I've now bought samples of every 18650
sized holder Digikey stocks) The contacts are better, but the interesting
part is the plastic gripping the sides of the cell is so tight that the
cell doesn't always slide in to make contact with the leaf spring contacts.
a light impact can cause the cell to slide compressing one spring far
enough to break contact at the other end - then it will not slide back
under spring pressure alone.

I've come to the conclusion that I need to tab the cells and either solder
a wire and connector to them or solder the tabs directly to the PCB.


I was only able to find one 18650 listed on Amazon with tabs, and it is
specified as a low drain type - not helpful.


Jean-Paul's suggestion was bang on. Stopped by Batteries plus on the way
home with four of my cells, they welded tabs on them for me and charged me
$4.50 for the lot.


Doesn't solve production level supply chain issues, but I'm back to testing
next week.

-Denny

Random add on question - is it still a "pack" if it's only one cell? Even
if it's tabbed/wired/shrink wrapped?
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