Re (2): low battery shutdown

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Re (2): low battery shutdown

Peter Easthope
From: Mike Dee <[hidden email]>, Mon, 22 Feb 2016 06:22:05 -0800
> contacts that electrically connect the battery to the
> laptop.* Dried green crystals have been spotted around the connector
> ... contacts that electrically connect the battery to the
> laptop.* Dried green crystals have been spotted around the connector ...

No sign of corrosion anywhere in or on the machine.  

> *Perform an XO Full Reset <http://wiki.laptop.org/go/XO_Full_Reset>.*

No problem there.  Brief orange flash is as described.

> *Disconnect the battery, and connect the laptop to AC power*. Now turn on
> the laptop. After the system has loaded, insert the battery.

> *Does the battery LED start flashing red?*

No.  Just steady yellow indicating charging.

> *Does the battery LED start flashing yellow?*

Just steady yellow.

Within about 40 minutes, mousing over the battery icon at
the top of the screen shows 100% charge.  The battery light
remains yellow for another 20 or so minutes.  Then changes
to green.

> Now
> disconnect AC power and discharge the battery while the system is running,
> keeping an eye on the percentage charge.
>
> *Does the system shut down abruptly with over 10% of charge remaining?* If

Probably about 30%.  Will do it again this weekend to verify the previous observation.

> Capacity test

OK, thanks.

From: James Cameron <[hidden email]>, Tue, 23 Feb 2016 06:18:55 +1100
> If a couple of full charge and discharge cycles don't fix the
> inconsistency, the battery is close to end of usable life.
>
> I agree with Paul that power-logs will be useful if Peter wants to
> dive deeper into the technical causes.

Will continue with the tests and tips.  

A battery specialty shop here in Vancouver made a nice job of
rebuilding a battery pack from an Epson HX-20.  Might let
them have a go at this battery.  If necessary will find a new
replacement.

These machines are superbly durable.  The battery pack will be the
first failure in most.  A modular battery with a "standard" connector
might be considered in a future design.  Recently I was given a
Duracell cylinder about 2 cm diameter with USB sockets on the end.
Should run many of little FPGA based machines.

Thanks!                 ... Peter E.




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http://easthope.ca/Peter.html Bcc: peter at easthope. ca

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Re: Re (2): low battery shutdown

smithbone@gmail.com
 > OK, thanks.
>
> From: James Cameron <[hidden email]>, Tue, 23 Feb 2016 06:18:55 +1100
>> If a couple of full charge and discharge cycles don't fix the
>> inconsistency, the battery is close to end of usable life.
>>
>> I agree with Paul that power-logs will be useful if Peter wants to
>> dive deeper into the technical causes.

Unfortunately, I never got around to implementing any sort of dynamic
calibration for the %/mAh.  The algorithm still treats your battery as
if it were new.

As others have said your battery is probably just showing its age.  1.5
was built in 2010-2011 so unless you got a new battery its 5 or so years
old.  That was the design life goal for each generation.

The rating was 50% available capacity after 2000 cycles. Only 30% loss
in 5 years of use is actually quite good.  A typical Li battery would
have long been trash.  It's one of the reasons we used LiFePO4 chemistry.

If you do run the capacity test I'd be interested in seeing your results.

--
Richard A. Smith
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