On 1/18/2017 11:57 AM, Benderthe.evilrobot wrote:

"David" wrote in message
news
I am in the process of using one of my old laptops for a specific
task. Of course, due to age, one of the issues I've come across is
battery life. Under any stress, the battery lasts maybe 20 min. If I
do nothing, it may go on for 45 min. Recently, I came across a few
videos where folks rebuilt their laptop battery packs and I'm
wondering if it's worth it for this old machine. Without too much
effort, I managed to disassemble the Lithium Ion pack and it is made
up of 9 cells labelled as Sony Energytec US17670 which, according to
my research, are 3.6 V cells and, as luck would have it, here is the
same pack disassembled:

https://wiki.droids-corp.org/article...nics/Accu.html

Now the big question is: 1) Is it worth it to replace these cells?
Some quick searching is showing them being quite expensive even for
"generic" cells which I understand probably wouldn't last any longer
than the time I'm getting now. The next question would be 2) If worth
it, what would be a suggested source for obtaining the replacements?
Finally (3) is there any way simple way to increase power on time of
these current cells? I have read of people putting them in the
freezer, etc, but I don't think that's for this type of battery.

If all else fails, I'll just continue using the AC adapter.

Thanks.

Apparently - some types have configuration data in volatile memory; if
you remove the old cells without providing a sustaining voltage, the
onboard controller chip becomes *VERY* dumb.



That's been my experience. Only had one successful rebuild. That pack
had a PIC processor and resetting it restored functionality.

There are other issues. You can't solder to the cells. If you get
tabbed cells and try to solder those together, the cells probably won't
fit back into the plastic.
I used a tab welder for all my experiments.

If you buy a "new" battery, it has probably been sitting in a container
in Arizona for a decade or two. If it works at all, it probably won't
be much
better than what you have.


If you have it professionally rebuilt, make sure to verify that they
can reset the chip so it will work in your computer.

For that vintage laptop battery, there are likely tools that let you
reprogram the protection chip after a rebuild. Last I looked
into it, the cost of the software was several times the cost
of a new battery.

If you can tolerate the AC adapter, just keep using it.



Presumably this can also happen if the battery gets completely dead -
but all the books are telling me that writes off the cells anyway.

But, back to the question. There are some things you can try.
If you have the test equipment, you can take the lid off the
pack and rebalance the cells. That's safest for the cells, but
very much more dangerous for you if you don't know what you're
doing.

There are calibration procedures that discharge the cells flat
by running the computer until it quits, then
recharge to full without interruption one or more times.
Problem with that is that if the cells are badly imbalanced,
you can cause the pack to shut down completely and refuse to
recharge.

The primary failure of laptop batteries is increased internal
series resistance.

The electrons are in the battery, but the protection circuits
won't let you have them.
The symptom is that the battery gauge says 100%, and seems to
be discharging normally, but at some point drops abruptly to zero.
If you turn off the battery features that sleep or shutdown the
system at some battery level, the laptop may run for very much longer.
Problem is that it shuts down abruptly and you lose whatever you're
doing and may have to chkdsk the drive to clean it up.
Once you become accustomed to how long it will run, you can often
manage that process manually.

The other problem is the same as the calibration issue. Discharged
to flat, the pack may permanently disable itself.

There are applications that can read the pack registers and tell you
what the battery thinks its condition is. It's very dependent
on the battery and the sensors in the laptop and the software.
You have to try several
to see if any work on your system.
I've had some success with PC Wizard. Versions 2008 thru 2012
were most helpful. Newer is not necessarily better for this function.
May have to try them all.

Are we having fun yet?