[ltp] Auxilliary external batteries

[Tom]

On Tuesday 13 May 2003 18:29, Theodore Ts'o wrote:
> On Tue, May 13, 2003 at 03:36:28PM +0000, Robert Hajime Lanning wrote:
> > 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.
>
> Absolutely true.  Also the case is that all of these auxiliary
> batteries (both the Electrovaya and the Valence) have a much higher
> energy density than as sealed lead-acid battery.  In fact, both
> companies have what seems to be an identical business strategy; they
> were started to commercialize some exotic, patented battery chemistry
> which is supposed to be allow for lighter, higher capacity batteries
> than the standard Lithion Ion batteries (which are themselves much
> lighter and have a higher energy density that lead-acid batteries).
> Both companies are producing these external batteries more as a way of
> marketing their propeitary battery technology and to show it off as a
> proven technology.  It's clear that what they really want to do is to
> license their battery technology to laptop manufacturers, since that's
> where the big money is....
>
> > >      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
> > >      =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
> > >      Total cost $68
> > >      Total weight 8.8 pounds
>
> So your solution gives you 90Wh, buth with a 75% efficient inverter,
> that's an effectively 67Wh battery.  To compare, the Valance N-Charge
> battery is 65 Wh, but it's 9" x 11" x 0.51", and it weighs 1.95 lbs.
> Yes, it costs $199, but at least for me, the volume difference of the
> inverter + 50W inverter is at least as important as the weight factor.
>
<snip>
> =09=09=09=09=09=09- Ted

The actual effective Watt-hours would be less.  To use the inverter you h=
ave=20
to use the AC adapter to power the laptop.  If you substitute a 12VDC to=20
"whatever voltage your laptopuses" converter you would get the 67WH effec=
tive=20
battery.  Of course the 12V battery setup is still cheaper but less=20
convenient.  I have seen batteries that come in nylon bags to make them=20
easier to carry.

Tom