Hi, David.
On 27/03/17 00:08, David Wright wrote:
>>> Complete discharge is instantly fatal, they can never wake up again.
>>> All lithium cells have rudimentary electronics to cut off discharge
>>> earlier than this, typically 2.8-3.0V per cell. Charging is relatively
>>> complex, constant current of about half capacity to around 4.1V, then
>>> constant voltage to fairly precise 4.2V, then when the current drops
>>> below a certain level, cutoff.
>>>
>>> It should be possible to leave a lithium battery permanently connected
>>> to the charger. No 'trickle charge' will occur, no additional current
>>> will flow until the cell voltage drops by a certain amount. But full
>>> charge is not recommended for long-term storage.
>>>
>>> Yes, I had to build a lithium battery into something a few years ago,
>>> I had to learn how to charge it.
>> Thank you for sharing these interesting comments. I think some time I've
>> inadvertently consumed the entire battery charge (although this was
>> something that happened a long time ago, I think). Perhaps the
>> recommendation to avoid this is to check the "Enable Power Management"
>> option in KDE.
> I didn't know you could. I thought the battery would stop supplying
> current before that happened. I was under the impression that to get
> any lower, you had to leave it empty so it could self-discharge.
>
> I ran a laptop on a faulty battery for 17 months. Throughout that
> period, the charge indicator flashed four yellows and a green. Apart
> from running down quite quickly, there were no other signs of
> distress. About a week before it finally gave up the ghost, I had the
> same behaviour as yours: removing the power cable would kill the laptop.
>
> The battery itself had a charge indicator when you pressed a button,
> lighting a steady line of one to five LEDs. When it died, just the
> 2nd and 4th LEDs flashed on and off instead, and the laptop wouldn't
> run at all.
>
> Fortunately, I had a spare (smaller) battery of the same vintage which
> is still going. (I won't say still going strong.) The laptop is also
> showing its age: the display gives problems most of the time so I run
> it hooked up to a monitor.
Thank you for sharing these experiences. In my previous email I was
talking about a full discharge because that's what I thought happened
when I saw the KDE charge indicator after I plugged in the charger once
the notebook shut down abruptly because I did not have enable the
"Enable Power Management" option of KDE. That's why I thought that it
would avoid that situation happens again
>> Do you think that of the information I showed in
>> /sys/class/power_supply/BAT0/uevent or
>> /org/freedesktop/UPower/devices/battery_BAT0 can be detected any
>> electrical problem with the battery?
> The only obvious oddity I can see is POWER_SUPPLY_STATUS=Unknown but
> I'm not sure I haven't seen that myself in the past, though probably
> only momentarily. But the voltages you see are a bit suspicious.
>
> I just ran this same laptop down to 7% capacity (takes about 20 minutes)
> and it was down at 10.797 volts. On reconnecting the power, it rose to
> 11.7 volts within, say, 15 seconds (but still reading 7% of course).
> So the low voltage you see with the charger attached might suggest
> that the battery is loading the charger somewhat. (Unfortunately you
> don't appear to get current amps, which may be related to Unknown above.)
I was observing these values:
------------------------------------------------------------------------
$ upower -i /org/freedesktop/UPower/devices/battery_BAT0
(...)
battery
(...)
percentage: 37%
capacity: 81,5333%
(...)
------------------------------------------------------------------------
But I'm not sure if that will be indicator of something. "Percentage"
seems to be the battery charge level. Looking at the upower
documentation I found this [1]:
The "Percentage" property: The amount of energy left in the power source
expressed as a percentage between 0 and 100. Typically this is the same
as (energy - energy-empty) / (energy-full - energy-empty). However, some
primitive power sources are capable of only reporting percentages and in
this case the energy-* properties will be unset while this property is set.
The "Capacity" property: The capacity of the power source expressed as a
percentage between 0 and 100. The capacity of the battery will reduce
with age. A capacity value less than 75% is usually a sign that you
should renew your battery. Typically this value is the same as
(full-design / full) * 100. However, some primitive power sources are
not capable reporting capacity and in this case the capacity property
will be unset.
I was comparing the values with those of the original battery:
------------------------------------------------------------------------
# upower -i /org/freedesktop/UPower/devices/battery_BAT0
native-path:
/sys/devices/LNXSYSTM:00/LNXSYBUS:00/PNP0A08:00/device:08/PNP0C09:00/PNP0C0A:00/power_supply/BAT0
vendor: SANYO
model: 45N1001
serial: 5581
power supply: yes
updated: Wed Nov 27 20:26:02 2013 (23 seconds ago)
has history: yes
has statistics: yes
battery
present: yes
rechargeable: yes
state: fully-charged
energy: 55.76 Wh
energy-empty: 0 Wh
energy-full: 55.81 Wh
energy-full-design: 56.16 Wh
energy-rate: 4.626 W
voltage: 12.53 V
percentage: 99.9104%
capacity: 99.3768%
technology: lithium-ion
------------------------------------------------------------------------
For example, for the current battery the "energy-rate" value is
extremely low:
------------------------------------------------------------------------
(...)
battery
present: yes
rechargeable: yes
state: charging
warning-level: none
energy: 18,31 Wh
energy-empty: 0 Wh
energy-full: 48,92 Wh
energy-full-design: 60 Wh
energy-rate: 0,00728571 W
voltage: 10,928 V
percentage: 37%
capacity: 81,5333%
technology: lithium-ion
icon-name: 'battery-good-charging-symbolic'
------------------------------------------------------------------------
> So if I were you I'd be buying a new battery in case the machine won't
> run when this old one completely fails. (I don't know about the wisdom
> of running with no battery; anyway this laptop looks as if the underside
> of the touchpad is very vulnerable when the battery is removed, and
> you lose two feet.)
Yes, as I mentioned in another message in this thread, I have already
contacted the supplier to go asking for availability and prices.
Thanks for your reply.
Kind regards,
Daniel
[1] https://upower.freedesktop.org/docs/Device.html
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