KenO wrote:
Hi Mike,

Thanks again for all your comments!

"Problem with lithiums is that they degrade whether you use 'em or
not."

Been trying to read everything I can find and came across " Recharging
when the battery hits 50% charge is the ideal to maximize its life."
http://madvapesfaq.com/knowledgebase.php?article=32 Does this
correspond to your experience?

All my batteries come in used computers. I have no knowledge of the
history or abuse of them. I've never put enough hours on a single
computer to notice any aging effects.
I've got so many laptop batteries in my fridge that I'm afraid
I'll break the glass shelf.

Also have you determined what the Max and Min Voltage should be for
Toshiba PA2490U 10.8 V 3600mAh battery pack?

It varies somewhat with chemistry, but 4.2V seems to be the absolute
maximum for cells of that vintage. So, 3 x 4.2 = 12.6V. But you should
verify that independently with the vendor to make sure. My lawyer made
me say that.
Minimum voltage is pretty much irrelevant.
When you're using your computer, your priority is to finish what you're
doing. Stopping when the battery reaches some voltage is
counter-productive.
You have no control over the thresholds set inside the battery pack
and the computer.

If you want maximum battery life, charge to 30% and put it in the
refrigerator.
Take it out occasionally and cycle it up and back down to 30%, then put
it back
into the fridge.
Won't do much computing in there, but will last a long time.

Worrying about it in actual use is also counter-productive.
Conventional wisdom is to recharge frequently keeping the voltage
up near max to reduce damage to do deep discharge.
But the forces that cause storage damage increase with voltage,
so you should keep the voltage as low as is practical. Can't win
there either...conflicting parameters for two different aging forces.

A laptop battery not fully charged when you need it is not helpful.

Keeping the temperature down seems to be the only effective remedy.



" I tried to use cells from a different good pack. It's a crap shoot
depending on the controller design. Some lose their brains when you
remove power and it's all over.
Others remember the previous capacity, so the new battery won't last
much longer than the old one. I've only found one battery pack with a
pic processor in it.
I managed to reset the pic and recovered it."

Have you posted these Li battery experiences any where? Would be
interested in learning more.
nope

The only Sony Li cell test I have found is http://www.stensat.org/Docs/battery_test_results.pdf
and the cell seemed to have been more affected by prolonged deep
discharge than overcharge.
There's likely a pressure sensitive switch in the cell that opens and
stays open when the pressure exceeds some level. The author's cell
probably did not vent. Some people claim that you can reset the switch
by poking a probe thru the hole in the + terminal. I was never successful.

I have several Dell 8-cell packs with EVERY cell open. I can understand
how more than one might open, but ALL of them at the same time?
One opening puts twice the current thru it's paralleled mate which
should cause it to open soon. But that should stop the current.

Bottom line...remember your priorities.
If you need your laptop, keep it fully charged.
Use it when you need it, turn it off when you don't.
That's about all you can do.

Ken