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Old March 3rd 17, 03:13 AM posted to alt.comp.os.windows-10,alt.comp.os.windows-8,alt.windows7.general
Rene Lamontagne
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Posts: 2,549
Default How to interpret laptop battery results.

On 3/2/2017 7:12 PM, Paul wrote:
Ken Springer wrote:
On 3/2/17 10:01 AM, Arnie Goetchius wrote:
Ken Springer wrote:
On 3/1/17 8:19 PM, Paul wrote:
Ken Springer wrote:
Let's say you run the powercfg command from the command line.

The battery design is 60,000, but the last full charge is 40,000.

Would it be accurate to say the battery has 66% or 2/3rds of it's
life
left? Or is some type of sliding scale more accurate, and maybe the
battery has only 40% of it's life left?

Is there an easy to understand web site for this? I'm not sure of
what
terms I should search for in this instance.

The term you want is "battery fuel gauge".

http://batteryuniversity.com/learn/a...ery_fuel_gauge

The connector on the laptop battery has room for serial connections,
allowing the CPU to query the battery IC.

The battery capacity declines with age. When Windows says "100% full",
it means 100% of the remaining 60% or original capacity the old
battery has.
You check the "hours and minutes remaining", as a means of
guesstimating
the Watt-hours the battery actually holds. If you laptop used to
say "three
hours" when the battery had just finished charging, maybe now it says
"two hours", under equivalent conditions. Of course, controlling the
conditions on a laptop is notoriously difficult.

Some fuel gauges, if they have not received a calibration cycle,
they count the number of times the battery have been charged,
and estimate the loss in capacity as a result. I'm sure the driver
software in Windows, cleans up any "inconsistent" information
so you won't get a scare like "105% full".

The battery IC is supposed to be "counting coulombs" or some such.
It does that, rather than using open circuit battery voltage
as some sort of indicator. Coulombs should be a better method,
than any voltage-based method.

Hi, Paul,

That's not the type of indicator I was referring to. I'm referring
to the
powercfg report available with Windows.

Open a command window.

Navigate to Windows\system32.

Type powercfg -energy -output power.html

It takes a minute or so for a report, power.html, to be created in
the system32
folder. You can use the full pathnames as you desire to end up with
the output
file where you would like it as well as change the name of the report.

Open the file in whatever, search for Battery Information. Those
are the
numbers I'm interested in.


The above is for Windows 7. I've read online that for 8 and 10, you
change
energy to batteryinformation. I don't have access to an 8 or 10
laptop, so
cannot confirm this.
I ran the "battery" option and got the following:

NAME DELL 7XFJJ4B
MANUFACTURER Sanyo
SERIAL NUMBER 8050
CHEMISTRY LION
DESIGN CAPACITY 73,260 mWh
FULL CHARGE CAPACITY 68,964 mWh
CYCLE COUNT -

Is that what you are looking for?


Looking for it? Nah, I found it. LOL

I'm looking for a way to interpret those numbers in "layman's terms".
How do I explain how much battery "life" is left when the battery is
used, such as in a used laptop I want to sell.

Can I say something like the battery has 94% of its expected life
left? Some kind of description/explanation the average person on the
street would understand.


http://www.techrepublic.com/article/...will-tell-you/


DESIGN CAPACITY mWh when it was new
FULL CHARGE CAPACITY mWh it holds when 100% now

That article has a bit more info.

Paul



That was a very interesting and informative article Paul, I applied it
to my Win 8.1 10 inch D2 tablet and the results where very enlightening.

The design figure was 29,600 MWH , but the 100 % full charge capacity
was 34,800 MWH, the battery must be better than specs tend to show,
much better than expected on about 18 month old tablet, Although I have
to admit it is hardly used very often.

Rene



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