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ForeverAgo

Member

Registered: 2013-02-07

Posts: 13

Benchmark the battery

Hi,

Here is the situation: I have a laptop with a broken screen. I could replace it for around 70$.
However, I would like to make sure the battery is good before doing so, otherwise the laptop is too old to justify a new screen + a new battery.

I tried to leave it on for as long as with the Wifi on, streaming from Pandora via pianobar with the internal screen backlight always on and the 8600M GS at 300Mhz memory and 300Mhz GPU, it lasted around 100 minutes. Not sure if this says anything.

Can anyone suggest a protocol to assess the battery's health over SSH (internal screen dead)?

Thanks,

ewaller

Administrator

From: Pasadena, CA

Registered: 2009-07-13

Posts: 19,768

Re: Benchmark the battery

Take a look in your /sys directory for files related to your battery.  On my machine:

ewaller@odin:/sys/class/power_supply/BAT0 1014 %cat charge_full
3855000
ewaller@odin:/sys/class/power_supply/BAT0 1015 %cat charge_full_design 
4400000

Post the contents of any interesting files you find

---

Nothing is too wonderful to be true, if it be consistent with the laws of nature -- Michael Faraday
Sometimes it is the people no one can imagine anything of who do the things no one can imagine. -- Alan Turing
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ForeverAgo

Member

Registered: 2013-02-07

Posts: 13

Re: Benchmark the battery

Thanks, I didn't know about this directory

lgp300 ~ $ cat /sys/class/power_supply/CMB0/uevent 
POWER_SUPPLY_NAME=CMB0
POWER_SUPPLY_STATUS=Discharging
POWER_SUPPLY_PRESENT=1
POWER_SUPPLY_TECHNOLOGY=Li-ion
POWER_SUPPLY_CYCLE_COUNT=0
POWER_SUPPLY_VOLTAGE_MIN_DESIGN=11100000
POWER_SUPPLY_VOLTAGE_NOW=12410000
POWER_SUPPLY_CURRENT_NOW=74000
POWER_SUPPLY_CHARGE_FULL_DESIGN=64094000
POWER_SUPPLY_CHARGE_FULL=4146000
POWER_SUPPLY_CHARGE_NOW=4065000
POWER_SUPPLY_CAPACITY=98
POWER_SUPPLY_MODEL_NAME=BAT1
POWER_SUPPLY_MANUFACTURER= LG 
POWER_SUPPLY_SERIAL_NUMBER=1234

ForeverAgo

Member

Registered: 2013-02-07

Posts: 13

Re: Benchmark the battery

CHARGE_FULL_DESIGN looks very strange, doesn't it? It looks like this leading 6 shouldn't be there because it doesn't really make sense compared to CHARGE_FULL and CHARGE_NOW

ewaller

Administrator

From: Pasadena, CA

Registered: 2009-07-13

Posts: 19,768

Re: Benchmark the battery

No, it does not look strange, but it does not look good either.  I do not know what the units are, but the design capacity is 6.4 x10^7 of them.  The last time you charged your battery to full capacity, it only took 4.1x10^7 of them.  4.1/6.4 or about 66% capacity.  Where as my two year old battery is at 39/44 or about 89% capacity.

Your battery is a fair way down the road

Edit:  Now that I look again, you are right.  There is an extra digit there.   Well, there are always 3 trailing zeros; may there is a bug and there should only be two on that line.  Or, your battery is really, really bad .  Not likely though, you did get a couple hours use out of it.  I'll stick with my guess of 66%.  It is not the case of an extraneous leading '6'; in that case your last full level would exceed the design capacity.  Not likely.

Last edited by ewaller (2013-02-13 15:58:24)

---

Nothing is too wonderful to be true, if it be consistent with the laws of nature -- Michael Faraday
Sometimes it is the people no one can imagine anything of who do the things no one can imagine. -- Alan Turing
---
How to Ask Questions the Smart Way

ForeverAgo

Member

Registered: 2013-02-07

Posts: 13

Re: Benchmark the battery

I see. I suppose POWER_SUPPLY_CHARGE_FULL and POWER_SUPPLY_CHARGE_FULL_DESIGN are expressed in µAh?
If so, shouldn't it be 5,200,000 as the battery pack reads 11.1V 5.2Ah?

Can I safely compare POWER_SUPPLY_CHARGE_FULL with 5,200,000 and consider the battery is at 80% capacity?

ewaller

Administrator

From: Pasadena, CA

Registered: 2009-07-13

Posts: 19,768

Re: Benchmark the battery

I see. I suppose POWER_SUPPLY_CHARGE_FULL and POWER_SUPPLY_CHARGE_FULL_DESIGN are expressed in µAh?
If so, shouldn't it be 5,200,000 as the battery pack reads 11.1V 5.2Ah?

Can I safely compare POWER_SUPPLY_CHARGE_FULL with 5,200,000 and consider the battery is at 80% capacity?

Sounds about right.

---

Nothing is too wonderful to be true, if it be consistent with the laws of nature -- Michael Faraday
Sometimes it is the people no one can imagine anything of who do the things no one can imagine. -- Alan Turing
---
How to Ask Questions the Smart Way

skunktrader

Member

From: Brisbane, Australia

Registered: 2010-02-14

Posts: 1,543

Re: Benchmark the battery

I believe you can use acpi to do all the math for you

$ acpi -b -i
Battery 0: Full, 100%
Battery 0: design capacity 4400 mAh, last full capacity 3873 mAh = 88%

ForeverAgo

Member

Registered: 2013-02-07

Posts: 13

Re: Benchmark the battery

lgp300 ~ $ acpi -b -i
Battery 0: Discharging, 97%, discharging at zero rate - will never fully discharge.
Battery 0: design capacity 64718 mAh, last full capacity 4196 mAh = 6%

Definitely a problem in the driver.

So the battery is good. But I'm still sitting on the fence regarding the screen, does paying 50$ for a new screen make sense on a 8600M GS laptop? I can't decide.