M
Post by a***@gmail.comPost by ~misfit~Post by a***@gmail.comAbout Misfit's advice that one doesn't need to discharge much below
5%, this seems to imply (to me) that the charging circuitry isn't
losing track of what constitutes a low charge, it is losing track
of what constitutes a full charge. Is this correct?
Sort of. As Mike pointed out older cells can develop high internal
series resistance (ISR). So it all depends on what your particular
battery pack uses to trigger various states. Most use voltage and,
if the ISR has risen, at lower voltages the cells still have the
energy stored but can't deliver it at high load levels. So, with
warnings turned off, when the computer asks for quite a few amps
(CPU usage goes up) it can die suddenly. The power is still in the
battery but it can only deliver it at low rates of current.
<...snip...>
Post by a***@gmail.comAnd this risk of bricking the battery -- from reading your
responses, it seems that this is a very plausible risk even if I
just run it to the point where the computer shuts down (not putting
it in a drawer for half a year). It's a bit ambiguous, because one
can interpret this as the point at which there is "no usable power
left", but then again, there was that story about high internal
resistance developing a high voltage drop once the laptop draws
current to do shutdown activities. As I said, I've got the laptop
set to do nothing when it reaches the Reserve battery level, but I
have zero trust that windows actually does nothing in the same way
as it does if you were to just yank the battery.
Are you not running the OEMs battery mangement software?
It's a Toshiba Satellite A660, and the 64-bit Windows 7 OS is the one
from the OEM install discs. The battery is also Toshiba, for this
laptop (perhaps for others as well, I never really looked into that).
Li-ion Battery Packmodel PA3817U-1BRS. An OEM webpage I found is
http://www.toshiba.com/us/accessories/Power/Batteries/PA3817U-1BRS.
There just doesn't seem to be a way to set the upper percentage level
at which the charger stops charging, and the lower percentage level at
which it starts charging. It charges to 100%, and as it discharges,
it encounters the Windows thresholds (Low, Critical, and Reserve) and
responds with the notifications and/or actions which have been
assigned to those events, e.g., sleep, hibernate.
Post by ~misfit~Post by a***@gmail.comAnyway, given this ambiguity, it looks like 5% is what you
recommend as a good level to discharge to if I just want to
recalibrate.
Yeah, it might not reclaim a huge amount of charge 'marked bad' but
it also shouldn't brick your battery pack.
Thanks. 5% is good enough for me. I'm interested in the gross
practices that can achieve gross improvements to longevity. Thanks!
There are several sides to this coin.
As a user, you get the best life out of your battery if you learn
what it can do and manage YOUR activities to maximize that.
Maximum charge level is hard to work around because it's automagic.
Having a programmable setpoint is about the only viable alternative.
But when you use it, what are you gonna do?
You've decided that you want to stop at 25%. Doesn't matter whether it's
manual or automagic. If you're in the middle of something, do you shut
down? Or do you finish your task? For most of us, having a battery that
needs replacement less frequently is small consolation when you couldn't
finish the presentation and lost the order.
So, you charge as frequently as you can and use it as little as possible.
If it doesn't do what you want you bought the wrong laptop, or need a
second battery.
From the vendor's perspective, as head of sales, do you want the ad
to say, 8-hr battery life? Or 5-hr battery life and saves 20% on battery
replacement costs, cuz all our other laptops abuse the battery?
Or maybe you say 2X faster processor and hide the fact that it hardly
runs long enough to boot.
These marketing guys are pretty smart. They know what sells.
The tablet-inspired expectation of 11 hour battery life is
affecting the whole laptop ecosystem. May not be long until
virtually every laptop follows the "surface" model of tablet
with keyboard. Most of us have wireless everything and don't
really need external ports.
Other factors include safety and protecting the replacement battery revenue
stream. Nobody with the frugal gene would ever buy a new battery at
retail. You can get crap batteries on ebay for cheap. Sad news
is that if you buy a "OEM" battery, you may get a crap battery
anyway. The plot thickens because the NEW battery
has been sitting in a container in
Arizona since the turn of the century.
Vendors can't have any of that!
I've seen laptops that refuse to boot with a counterfeit battery installed.
Some will run but won't charge. (you see that same symptom with some
counterfeit power bricks)
Others, give you a warning that you have to dismiss.
Some run the computer, but the battery gauge doesn't work and any
test reports "battery not installed."
The vendors want you to buy new laptops frequently. And batteries
are priced/specified to encourage that. Everybody wins...unless
you're concerned that, one day, the entire surface of the planet
might be covered in busted laptops.
The technology is quickly evolving. Batteries, some, but management
technology has come a long way. Vendors find it more marketable
to manage the best they can and replace the battery at your expense
frequently.
There are a number of battery management technologies, but the trend
is to make is impossible for a mere mortal to fix one.
Back in the day, I'd match NiCd's and re-cell. Turn 3 bad ones into
one good one. You can't solder battery packs together.
Even if you're crazy enough to try to solder on them,
there's so little clearance that the blob won't fit the case.
If you get the tabbed ones and solder the tabs, there's often
insufficient room to fit the tabs in.
I have two generations of DIY tab welders and a real
CD spot welder. Most of that is useless today. You can change the
cells, but if the chip won't let you use it, you're done.
If you crack the case on a Lithium battery, you can sometimes charge
each cell individually to balance it and it may run the laptop, subject
to all the issues stated above. I buy laptops with busted screens.
The battery is worth more than the value of trying to find a screen.
Working laptops at garage sales always have bad batteries. That's
why they are for sale. Ones with busted screens sometimes have
usable batteries. It's worth a buck to find out.
So, who cares about any of this?
Cheap bastards like me!
Statistically, the percentage is near zero.
IF you use your computer to make money, the cost of a
replacement battery is noise level.
My life revolves around frugality and prospecting for deals.
I buy a lot of stuff at great prices.
I try not to think about the fact that I could have bought
one new computer for less than the prospecting costs of the
dozen crap laptop treasures I have hanging around.
That's why I call it a hobby.
THEY call it hoarding. What do they know? I can stop any time
I want... ;-)
There's a set of freeware diagnostic tools called PCWizard.
Last I checked, the sweet spot was the 2010 version, but it's
worth a try at the newer versions.
There's a battery tab that shows you what the pack thinks it
is, design capacity, current capacity, current state of charge,
voltage etc.
Whether it works for you is a crap shoot depending on whether it supports
the methods/protocols used by your laptop. Do a reality check on
the numbers presented by battery analysis software. Because of the
different protocols in the wild, sometimes the numbers are just WRONG.
Don't fix it if it ain't broke.