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Wispy

Member

Registered: 2021-04-02

Posts: 28

Suddenly battery capacity is incorrect

I have an old laptop (almost 10 years old), the battery health isn't great but that's not the concern. Recently I noticed that it only charges upto 30%ish percent according to i3status. But today I have let it running for a couple of hours, and it was stuck at 1.81% for almost an hour now. I understand that my POWER_SUPPLY_ENERGY_FULL is about 30% of POWER_SUPPLY_ENERGY_FULL_DESIGN. But when it reaches 1.81% (730000), POWER_SUPPLY_ENERGY_NOW doesn't go down, it may fluctuate back and forth a bit but overall it stays the same.

So the problem is that now I have no idea of how much battery I have remaining at any time past those 1.81%. Is there any way to diagnose this issue further and hopefully get it fixed?

The laptop is Lenovo IdeaPad G505, the system was last updated yesterday, the battery was never replaced.

cat /sys/class/power_supply/BAT1/uevent

DEVTYPE=power_supply
POWER_SUPPLY_NAME=BAT1
POWER_SUPPLY_TYPE=Battery
POWER_SUPPLY_STATUS=Discharging
POWER_SUPPLY_PRESENT=1
POWER_SUPPLY_TECHNOLOGY=Li-ion
POWER_SUPPLY_CYCLE_COUNT=0
POWER_SUPPLY_VOLTAGE_MIN_DESIGN=10800000
POWER_SUPPLY_VOLTAGE_NOW=10579000
POWER_SUPPLY_POWER_NOW=9933000
POWER_SUPPLY_ENERGY_FULL_DESIGN=40400000
POWER_SUPPLY_ENERGY_FULL=12390000
POWER_SUPPLY_ENERGY_NOW=730000
POWER_SUPPLY_CAPACITY=5
POWER_SUPPLY_CAPACITY_LEVEL=Low
POWER_SUPPLY_MODEL_NAME=PABAS0241231
POWER_SUPPLY_MANUFACTURER=LG 
POWER_SUPPLY_SERIAL_NUMBER=41167

ewaller

Administrator

From: Pasadena, CA

Registered: 2009-07-13

Posts: 20,230

Re: Suddenly battery capacity is incorrect

My suggestion is to let it run until it shuts off. Then charge it fully.

Battery controllers for Lithium chemistry secondary batteries keep track of battery charge using the notion of 'Coulomb Counters' -- essentially integrating the current into and out of the battery as a function of time.  Given enough time and cycles, small offsets are integrated and the resultant errors can become large.   Your battery is discharging, but seems stuck at a couple percent because the battery had more charge than the 'gauge' said..  When it finally shuts down, the 'gauge' and the battery itself will both be at zero.  The next charge should keep them in sync.  But, the Coulomb counter will still drift over time so this process needs to be repeated every so often.

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Wispy

Member

Registered: 2021-04-02

Posts: 28

Re: Suddenly battery capacity is incorrect

Thanks for the answer. I will try it out but whenever the battery gets too low, I noticed the computer goes into an endless booting loop (i suppose until the battery completely runs out of "fuel". Any idea what could cause that? The screen stay turned off and I don't think it takes any input.