[ltp] Running with line power and no battery

[Micha]

On Fri, 29 Feb 2008 12:21:59 -0500
Paul Fox <pgf@foxharp.boston.ma.us> wrote:

> desrosiers wrote:
>  > I've had Thinkpads consistently for the last 10-12 years, and I've tri=
ed
>  > two distinct usage patterns, both of which seem to have a very negative
>  > effect on battery life:=20
>  >=20
>  > 1. Plug in the laptop with the battery attached, use it until the
>  >    "Battery is fully charge" alert comes up, then disconnect AC, and
>  >    run exclusively on battery. When the low-power alert comes up, plug
>  >    AC back in and continue to work until the laptop battery is at 100%
>  >    charge again.=20
>  >=20
>  >    Lather. Rinse. Repeat.
>  >=20
>  >    Time and time again, across about 7-8 different Thinkpad laptops,
>  >    this has proved to "kill" a battery before the initial warrantee
>  >    period of the battery expires (i.e. no longer holds a charge). A=20
>  >    call to IBM for a replacement battery, and you can start all over
>  >    again.=20
>  >=20
>  > 2. Charge battery to full while on AC, then remove the battery, working
>  >    only on AC power. When you need to disconnect from AC (or work
>  >    mobile), plug the battery in and use until the low-power alert comes
>  >    up. At this point _switch_ the battery for a full-charged second
>  >    battery.
>  >=20
>  >    Take the first battery and use the "Battery Rundown" tool to fully
>  >    drain the battery (usually will provide at least 1 more hour of
>  >    "life" past the low-battery audible warning alerts). I've usually
>  >    done this before the end of the day, so I can then plug the laptop
>  >    into AC with a _fully_ run-down battery, to charge it to full by the
>  >    morning commute outbound.
>  >=20
>  > Both of these approaches seem to rapidly kill Thinkpad batteries (dire=
ct
>  > from IBM, not third-party replacements).=20
>  >=20
>  > I spoke to an IBM tech at one point about #1 above, and he recommended
>  > that as the best way to ensure you don't "prematurely age" the battery.
>  > He said that keeping the laptop plugged in while the battery was fully
>  > charged was a bad idea, if I wanted to ensure long life from that
>  > battery. My own tests confirm and validate this.
>=20
> i'm confused.  it sounds like the ibm tech was recommending the very
> method that caused you to prematurely kill batteries.  but he also said
> that not unplugging was bad for batteries too.
>=20
> can you rephrase?
>=20

Not sure what he said, but AFAIK modern batteries like a constant trickle
charge, don't like to be overheated, fully charged or fully discharged. Not
sure what's with overcharging but I was told that when they get close to em=
pty
the cells don't empty out at the same rate and the fuller ones cause backfl=
ow
killing the ones that emptied faster.

Since this is a travelling laptop, I'm trying the approach of charging to 9=
0%
with the charge limit threshold and as much as possible stay above 30%
(although I started using it to take notes in classes, and when they run ab=
ove
three hours the battery tends to run too low).

We will see how long it takes to die ...

> paul
>=20
>  >=20
>  > > My 9-cell and bay batteries are at 95% of their design capacity after
>  > > two years of use (proper storage at 10C).
>  >=20
>  > 10=C2=B0C is 50=C2=B0F... are you storing these in your refridgerator =
in a ziplock
>  > or something? Keeping them in a metal container in your basement or
>  > cellar?=20
>  >=20
>  >=20
>  > --=20
>  > David A. Desrosiers
>  > desrod@gnu-designs.com
>  > Skype...: 860-967-3820
>  >=20
>  >=20
>  > --=20
>  > The linux-thinkpad mailing list home page is at:
>  > http://mailman.linux-thinkpad.org/mailman/listinfo/linux-thinkpad
>=20
> =3D---------------------
>  paul fox, pgf@foxharp.boston.ma.us (arlington, ma, where it's 18.1 degre=
es)