What the... my laptop battery LIES!

Discussion in 'PC Hardware' started by bear_aussie, Jan 10, 2018.

  1. bear_aussie

    bear_aussie MDL Member

    Jun 8, 2015
    I have a weird problem with my years-old netbook, an amd-based acer aspire 1

    everyones seen batteries that get down to 50% or last ten minutes off the charger and then their laptop dies, but I have the opposite problem

    if I override/ignore the "critical battery 5% your gonna die soon!" warning (that I get within an hour of taking it off charge), it runs for AT LEAST (I haven't managed to run it till dead yet) another hour and a half!

    ive reinstalled windows (7/32) since I remember reading somewhere that windows "calibrates" itself to the battery so it can tell you if your battery is losing capacity and/or take decent guesses on what battery level it should kick it into hibernate, etc

    but it still says "consider replacing your battery" and still sleeps my laptop (it cant hibernate cos my widnows is in a vhd) with well over an hour of runtime to go

    I went and poked deeper. fired up cupid hwmonitor and took a look at my battery stats: its design capacity is about 47 watt-hours, but it says the capacity is only 15wh (degradation of 70%). current charge says 15wh and when unplugged, drops like a rock for an hour to 0.91wh when it hits critical battery and sleeps

    wake it up - yep, 910mwh, 5% charge remaining
    run for half-an-hour - still at 910mwh, 5%
    watch an 720p episode of something for 3/4 of an hour (hard work for a 1ghz fusion - both cores at 100%, cpu temp 85 degrees) - STILL at 910mwh, 5%

    only clue that im hurting the battery is that the terminal voltage (normally 11.1v) has sagged to about 10.9 in the last hour and a bit since it "died"

    has anyone else seen this before? and more importantly did you find a way around it?

    TIA, bear
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  2. R29k

    R29k MDL GLaDOS

    Feb 13, 2011
    What he is doing there is the calibration method, you disable the shutdown and just run it.
  3. kaljukass

    kaljukass MDL Guru

    Nov 26, 2012
    Each Li-ion battery will lose from its nominal capacity of 24% -26% after the first three months, with about the same happens during next 3 month when it loses from remaining capacities again abot 25%.
    So, good battery life is about a year, after year there is about 15% -20% of the original capacity remains, and this battery is essentially unusable for laptop.
    If you say that your battery is old for years, then it is very good batery, if its remaining capacity is still 15%, such a things happens rarely. Usually is any battery useless after year or two.
    PS. With home tools, you can not measure it in any way and no computer gadget can measure it in any way. You can only get an estimate, which based on the battery voltage level and how long takes to go minimum allowed voltage level. But this is just an estimate, not a real result, which is obtained by measuring.
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  4. bear_aussie

    bear_aussie MDL Member

    Jun 8, 2015
    ta for the interest fellas
    did look into that, yeah. couple of battery monitoring utilities was all acer were offering my my flavour of laptop alas :(
    i think the problem is windows cant really "calibrate" against a lying battery - if it takes an hour to go from 15wh to 1wh windows is gonna assume I have about... *MATHS* 4 minutes until its dead
    I dunno what your doing to your poor batteries mate :p, ive only seen real performance dives in my laptop batteries after a couple of years (when they get to under 50-60% of their design charge)

    ill admit tho I tend to treat my batteries "well"... don't leave them for weeks on the charger (li ions hate being kept at high charge), tend close up and sleep when they get below about 20% (they hate deep discharge even more). but mine do cop a hell of a lot of charge cycles - this one has been charged from 20% (below, lately!) up to 100% at least four days a week since 2012

    windows can only go on what the battery says its at - ill bet it isnt consulting the terminal voltage at all which as I said stays rock-solid at 11-11.2 until about 130 minutes off the charger when it starts to sag

    I understand that the batteries in laptops tend to be batter PACKS: a wodge of 18450 li onss at 3.7v each... mines a 6cell battery so it must be a pair of three in series to make my 11.1v terminal voltage... plus a "brain" to keep them balanced when charging, skip cells that are acting up (so there's no FIREY CRATER where your laptop used to be) - and of course give a half-sensible readout of what theyre capacity is at - and that's whats giving bad numbers to my laptop methinks

    hmm... does anyone think that the battery might have firmware than I can fiddle with? or perhaps I could attack windows itself - maybe a custom battery driver that could massage the numbers before windows gets a crack at them?
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  5. Hadron-Curious

    Hadron-Curious MDL Guru

    Jul 4, 2014
    For the umpteenth time, you can drain the battery completely and clear your CMOS.
  6. bear_aussie

    bear_aussie MDL Member

    Jun 8, 2015
    thanks guys, but I caved i have a new battery coming in in the next few days

    AU$34. prolly woud have cost me more than that to fix/patch the current one
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  7. Hadron-Curious

    Hadron-Curious MDL Guru

    Jul 4, 2014
    Please, get us posted on the condition of the new battery.
  8. bear_aussie

    bear_aussie MDL Member

    Jun 8, 2015
    #9 bear_aussie, Jan 18, 2018
    Last edited: Jan 19, 2018
    np interested proton (or are you a neutron?) it just arrived today :headbang:

    ive plugged it into my laptop - came with the factory set of electrons (was at 53% charge when I hooked up) and its charging slooooowly (its only up to 56% in 20 mins!) cheap 40w charger :coffee:

    but theres probably a reason for that it claims to have FIVE TIMES the capacity of the "dead" battery (74wh vs 15wh) :shock:
    if it speaks the truth (from ebay so anything can happen... :pray:) it shoud give me about 10 hrs runtime :party_time:

    edit: just over 2 hours charing now at 94%

    edit 2: got sick of waiting for it to charge so abandoned library and stuffed it in my bag at 95% popped it open when I got on the train and started working (new install of windows, still needs configuring...)

    after about 15 minutes. woo! been a while since I got to see an estimated time to death (its only given percent for years now)

    AND CHECK OUT THOSE TERMINAL VOLTAGES - acer (actually sanyo) crammed some power into this one!

    ive noticed that the battery does get a little warm - not hot but I should probably figure out how rweverything works so I can talk to the battery (the battery is "smart", with temp sensors and everything, but their only accessable via smbus - acpi doesn't expose the info) and confirm theres nothing iffy going on

    20 mins later, was thrashing the machine (resetting acls on about 155000 files) so it took a nose dive

    recovered some once it was done :)

    was interested to see what happened here - ive burnt through my first 15wh. took slightly longer to do that the old battery did. windows didn't complain, no errors, no sudden sleep mode. the battery meter decided to be an old fart tho, so got runtime info from wmi:

    C:\Users\bevan>wmic path win32_battery get estimatedchargeremaining,estimatedruntime
    EstimatedChargeRemaining  EstimatedRunTime
    80                        429
    429 (its in mins) = 7hrs 9mins

    anyway im home now after 80 mins of runtime having only eaten 15% of the battery that was never fully charged in the first place - should hook it up and fix that :)

    edit 3: fully charged now, but its 10 oclock at night and should probably sleep the battery o/night to let the terminal voltage settle and ensure decent electron diffusion (and all that jazz)

    I prolly wont get 10 hours out of this thing as a matter of course - but its looking like 8 is achievable. cross fingers, my little netbook is a road warrior again! :D

    FINAL EDIT PROMISE: :blahblah1:
    finally got around to a full-house rundown check (didn't take pictures this time)

    blundered out my door about 2am for a smoke (I don't smoke in my flat), never bothered to reconnect when I came back inside, and at about 2.25, thought id be clever and put winsat formal on a loop
    laptop got WARM, temps near 90C, fan a-buzzin :hot:

    after hurling politically-charged insults at anons on 4chan all night (wew lads), finally threw "your battery is gonna die!" at EIGHT FIFTEEN - nearly six hours at absolute full-pelt :yeahyeah:

    battery terminal voltage dived alarmingly low (10.1v!) so I don't think ill be doing it again tho

    intrestingly it doesn't register battery capacities below 3% (meter goes 5, 4 ,3, 0) so think ill go with 7% low, 5% reserve, 3% critical in power control panel - giving me 10-20mins between low warning and autosleep

    been recharging for a bit over an hour now - back up to 21% :D

    funny thing - sometimes it wont charge: plug in, it beeps... but the battery light flashes (instead of solid on) and windows says "plugged in not charging". might need something with more kick than the stock 40w charger to push electrons into this little power station :g:
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