On 11/15/2017 10:00 AM, Jeff Liebermann wrote:
On Wed, 15 Nov 2017 09:52:00 -0500, Bob Engelhardt
wrote:

On 11/15/2017 12:09 AM, Jeff Liebermann wrote:
...
If you're having problems charging cells which exhibit low terminal
voltage (under about 2.5v), try this:
https://www.youtube.com/watch?v=tbEfhPbqTDE

I came away with this clever tip: use small magnets to hold test leads
to the ends of cells.

Yep. However, I suspect that may have been an accidental discovery.
When one salvages 18650 cells from a laptop battery pack, the
resulting cells do not have a projecting button top on the positive
electrode. Getting such a cell to make a proper connection in a
battery holder or flashlight is problematic. So, someone determined
that a tiny magnet will stick to the positive terminal and provide a
suitable button top contact (and test lead connection):
https://www.ebay.com/itm/New-15pcs-Battery-Magnet-Spacer-Convert-Flat-to-Button-Top-All-Lithium-ion-/282548150944

Or you can get the ones not specified as battery extenders
https://www.ebay.com/itm/N35Super-St..._i4k 0pOrvRVw
for 3-cents each in hundreds.

If you get some square magnets, you can wrap a piece of battery tab
material around them. Leave some sticking out so you can
solder a wire or put a clip on it. Works for charging all types
of batteries with magnet-attractive connection points. And the current
doesn't go through the magnet or depend on the surface plating.