[ltp] Auxilliary external batteries

[Robert Hajime Lanning]

On Tue, 13 May 2003, Bob Toxen wrote:
> Keep in mind that all these auxiliary external batteries are is a
> 12V rechargeable battery, charger, and inverter.  My R31 used about

No, there is no need for an inverter.  Not AC.  The brick that comes
with my TP600X outputs 16Volts DC at 3.36 Amps.  These external
batteries are just 16Volt high current batteries.  I don't plug the
power supply into the battery, I plug the battery directly into the
notebook.

Now, I haven't measured the real amperage that the notebook pulls.  I am
just reading the labels.  So, the active amperage will be lower.

Now, this is from the rating label from the "56W" brick.  The newer
notebooks, like the T40 I want to get, are 75W.  (Probably still 16V)

> 150 mA (from the wall) with the display active and the disk spinning
> and next to nothing without the disk running.
>
> If the inverter is 75% efficient, call that 200 mA.  This is 24 W,
> requiring 2 A from a 12 V battery.  For a 30% disk duty cycle, that is
> an average of 0.67 A.  For a 12 hour transatlantic (must be Pacific)
> flight, that would require an 8 AHr battery.  a 50 W inverter would
> work fine.  Actually, you would get 15 hours because when the inverter
> battery runs down you still would have a fully charged internal battery.
> Mine is spec.'ed for 3 hours.
>
>      50W inverter: $25 at www.microcenter.com (about 0.3 pounds)
>         or about the same price at www.batteriesplus.com
>      7.5 AHr 12V sealed lead acid battery would weigh 6 pounds
>         Model CLTXPA12-7.5F via www.batteriesplus.com $26
>      Battery charger (1A would recharge in about 10 hours)
>         2.5 pounds via www.batteriesplus.com $17
>      ===========================================================
>      Total cost $68
>      Total weight 8.8 pounds
>
>      Quality construction, fully warranted, easily replaceable.
>      Note: Batteries Plus does not ship from its web site but
>      their Duluth, Georgia store does mail orders +770 495-1644.
>      (They have batteries for absolutely anything; I'm not affiliated
>      with the company.) Hmmm.  I might just do this for my upcoming
>      talk in San Jose.
>
>      The form factor and weight of the above might be slightly less
>      desirable than the commercial products but at a fraction of the
>      price, unless someone else is paying for it, it's a no-brainer
>      to me.  The knuckle-draggers at airport security might get
>      suspicious and cause you hassles with a home-brew solution, though.
>
> Bob Toxen,
> Fly-By-Day Consulting, Inc.
> http://www.verysecurelinux.com       [Network & Linux/Unix Security Consulting]
> http://www.realworldlinuxsecurity.com [My 5* book: "Real World Linux Security"]
> bob@verysecurelinux.com (e-mail)
>
> The talks I'm giving on Linux security this year include:
>   at IBM's Linux Competency Center in New York City on March  6
>   at the Atlanta SecureWorld Expo in Atlanta        on May   22
>   at the Enterprise Linux Forum in San Jose         on June  04
>

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