Digest for sci.electronics.repair@googlegroups.com - 4 updates in 2 topics

"Benderthe.evilrobot" <Benderthe.evilrobot@virginmedia.com>: Jan 18 07:57PM

"David" <devotedobserver@thesky.net> wrote in message
news:o5njru$t61$2@dont-email.me...
> 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.
 
Presumably this can also happen if the battery gets completely dead - but
all the books are telling me that writes off the cells anyway.
mike <ham789@netzero.net>: Jan 18 07:50PM -0800

On 1/18/2017 11:57 AM, Benderthe.evilrobot wrote:
 
> 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?
Jon Elson <jmelson@wustl.edu>: Jan 18 03:27PM -0600

Jon Elson wrote:
 
I've replaced the valves, again, and the relay, Waiting a few
> days to see if the trouble recurs.
Well, it's been over a week, the machine is running great. So, problems
solved until next time! (Yes, there always seems to be a next time!)
 
Jon
bruce2bowser@gmail.com: Jan 18 04:09PM -0800

And if you want, some junk yards and metal recyclers have a we-buy-all-appliances policy. Call today.
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