Re: Issue with notebook (maybe the battery?)
On Sun 26 Mar 2017 at 17:09:01 (-0300), Daniel Bareiro wrote:
> Hi, Tomás and Joe.
>
> On 26/03/17 07:49, Joe wrote:
>
> >>>> [snip]
> >>>>
> >>>> Checking the purchase invoices, I bought the notebook on September
> >>>> 19, 2013, and then changed the battery on November 2, 2015. So
> >>>> less than two years ago I have this battery.
> >>>>
> >>>> The notebook I use it practically every day and I leave it
> >>>> sleeping from one day to the next so I do not have to open every
> >>>> application every time. I'm not sure if that impacts so much on
> >>>> the battery life.
>
> >>> If it was a long term degradation, possibly. With some battery
> >>> technology/technologies(?) there is a "memory" effect. If there is a
> >>> repeated "shallow discharge"/recharge cycle ( sleep overnight
> >>> followed by running during day with charger plugged in) the
> >>> effective battery capacity will decrease. IIRC that applies to only
> >>> one technology but can't remember which.
>
> >> That would be the nickel family (NiMH and its predecessors). Laptops
> >> changed long ago (I'd venture somewhere in the 90-ies) to Li-whatever.
>
> > Lithium isn't particularly sensitive to state and depth of charge,
> > apparently the optimal long-term storage state is about half-charge.
>
> >> Those have other weak spots: overcharging shortens their lives,
> >> especially being overcharged *and* higher temps. More overcharging
> >> leads to fireworks. They *need* some electronics to take care of
> >> that. Deep discharge is also fatal to their lifetimes.
>
> > 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.
> 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.)
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.)
Cheers,
David.
Reply to: