On Sun, 20 Oct 2013 00:47:42 +0000 (UTC),
wrote:

I sometimes leave a device unused for years. Other times I leave it plugged
in. Is there a poor man's guide to fixing batteries with "memory" (or
whatever) problems?

There's no such thing as "memory effect" but there are other problems
with similar symptoms:
http://en.wikipedia.org/wiki/Memory_effect

There's no way to "fix" a dead or dying battery. The best you can do
is test your batteries. I use a West Mountain Radio CBA-II:
http://www.westmountainradio.com/cba.php
http://802.11junk.com/jeffl/NiMH/cba-II.jpg
Charge the battery as best you can, and run a discharge test. For
example, a common NiMH AA battery:
http://802.11junk.com/jeffl/NiMH/Energizer-NiMH-2300.jpg
The battery capacity, in amp-hrs is the point where the voltage starts
to drop. If the battery pack does not meet your expectations, or does
something disgusting, either tear it apart and rebuild it, or recycle
and replace it.

There is also a wide variety of good (and bad) advice on how to extend
your battery life. See the various articles at:
http://www.batteryuniversity.com
http://gizmodo.com/5952938/everything-you-need-to-know-about-batteries
http://www.mpoweruk.com/failure_modes.htm
under the appropriate chemistry.

I find that the limiting factor to battery life is the charger design,
especially the EOC (end-o-charge) detection. Rather than think about
how one would extend battery life, think about all the ways one could
intentionally destroy a battery with a charger. For example:
1. Charge beyond 100% capacity.
2. Forget to turn off.
3. Re-start the charge cycle when the AC power hiccups.
4. No battery cooling.
5. Quick charge a battery that can't take a quick charge.
6. Overly simplistic charging circuit without stages or EOC
detection.
7. Failure to recognize a dead battery and charge it anyway.
8. EOC detection by battery heating. If the battery gets warm, it's
already overcharged.
9. Failure to recognize that the battery is under load, such as
operating a cell phone while charging.
10. No accommodation for Li-Ion battery inflation when charged.
11. etc.

I've seen all of these in various devices. The problem is that
manufacturers believe consumers are more interested in fast charge
times and long run times, than they are in battery life. So, they set
the charge controller to as close to 100.0% as possible, and charge to
this point as fast as possible. The result is short battery life.
Fortunately, some laptop manufacturers now have a setting in the CMOS
to allow charging to something less than 100.0% in order to extend
battery life.

With Li-Ion, there are problems at both ends of the charge scale. See
the chart at:
http://www.mpoweruk.com/lithium_failures.htm
Note that the acceptable range of charge and temperature (green area)
is outside of where literally all users and chargers operate Li-Ion
batteries. In short, operating a Li-Ion battery solely for long life
is difficult, if not impossible. The article continues with other
ways to kill Li-Ion batteries.




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