On Thu, 8 Feb 2018 07:07:29 +0100, Tosspot
wrote:

On 07/02/18 20:23, sms wrote:
On 2/6/2018 8:48 PM, Jeff Liebermann wrote:
On Tue, 6 Feb 2018 10:52:50 -0800, sms
wrote:

My wife's Lezyne Deca 1500XXL stopped taking a charge, at all. Taking it
apart, I saw that the batteries were made in July 2015. Not too good for
it to stop working that soon. These lights don't have user-replaceable
batteries, but by removing two screws I was able to open it, and the
battery pack does have a connector on it so at least they didn't solder
it directly to the printed circuit board.

I don't see a problem.* If your wife used the light every day for
about 2 years, that would be 730 charge cycles.* That's about the
correct lifetime for a 60% DoD (depth of discharge).* See table 2:
http://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries

Just adding to this, a lot of people don't realise LiIon batteries die
without doing anything to them. In other words, you can't just simply
count recharge cycles if they are infrequent.

https://batteryworkshop.msfc.nasa.go...att_KBugga.pdf

That's for LiIon batteries that might be used in a space mission,
where long "storage" life, until needed, it important. Even so,
NASA's own conclusion (at end of report) does not suggest that the
cells self destruct without doing anything to them:

Lithium ion cells have thus far shown impressive storage
characteristics at low to warm storage temperatures
– Over 90% capacity available at ambient and low storage
temperatures.
– Retain good low temperature capability after storage.
– Marginal increase in the impedance, possibly from cathode
interface.
• Lithium ion batteries show good promise to meet the needs
of long-life space missions (or terrestrial applications, e,g
biomedical) but require continued validation from such
real-time tests.

The "continued validation" means:
"More research is necessary. Send funding".

What I've found in my disorganized testing is that I can throw a few
charged LiIon batteries into my dashboard glove compartment, located
to top of the dashboard where the sun can easily turn it into an oven,
cram the battery into my cell phone or flashlight, and get about 90%
of the capacity of a freshly charged battery. I've been doing such
battery rotation with cell phone batteries for about 10 years without
any problems. I've also been doing it with 18650 and 14500 flashlight
cells for about 2 years, also without any problems.

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558