From: Benjamin Koh (benkoh_at_stanford.edu)
Date: Wed May 31 2000 - 19:13:11 EDT
I guess I wasn't clear enough. These high-capacity batteries I am
talking about are DIY affairs. They are not new technology - lead-acid
batteries have been around a long time. They will most certainly not fit
into a TP battery bay. TP batteries are fairly small and contain
on-board electronics to accurately determine remaining charge. Lead-acid
batteries are neither small (their low energy density precludes this)
nor "smart" - your car can't tell when the battery is low - it either
starts the car or it doesn't. Ditto for any such rig you make yourself.
These battery rigs essentially tell your TP not to use the onboard
battery because there is an external power source.
The batteries can be bought in a "slab" form factor and fit under the
TP. My university computer store has the commercial versions of these
that plug straight into specific Apple Powerbooks. So you can be assured
that the principle is sound. In fact I remember reading a press release
online not too long ago about a commercial version for TPs. Apparently
they were able to double a 560x runtime before the TP switched to its
own battery, or something like that. Search on Google :-) Again, these
were in the form of slabs that fit under the TP.
Benjamin
STeve Andre' wrote:
>
> Thanks for this, Ben. I haven't kept up with batteries for about 4 years
> now and don't know that the newest technology can offer.
>
> But can you get these newer high-capacity batteries in the currently used
> form factors, such that they could be used in today's existing ThinkPads?
>
> STeve
>
> At 12:29 PM 5/31/00 -0700, Benjamin Koh wrote:
> >As a matter of fact, one can find many pages on the web devoted to
> >building super longlife batteries for laptops, digital cameras and
> >camcorders. Most involve purchasing a (heavy) lead-acid battery of some
> >sort. They are available in a "slab" format that will fit under your
> >laptop, or if you like you can also buy the traditional type that goes
> >in a car. What's needed is basically a converter. You can:
> >
> >a) use an inverter to generate AC and plug the TP's AC unit into it.
> >b) use a voltage regulator and plug the TP directly into it.
> >
> >Most of the batteries seem to be available in capacities up to 7000 mAh,
> >maybe more. Given that most TP batteries store around 3000 mAh, you're
> >looking at double time, perhaps 1.5 to 1.75 times if you discount for
> >inefficiencies in conversion.
> >
> >Advantages: super long life, very high cycle duty, cheap (compared to
> >Li-Ion)
> >Disadvantages: size, weight, some assembly required
> >
> >Benjamin
> >
> >STeve Andre' wrote:
> > >
> > > Randal, show me the battery that could do this and I will buy one for
> > you, too!
> > >
> > > STeve
> > >
> > > At 10:35 AM 5/31/00 -0700, Randal Whittle wrote:
> > > >At 04:13 PM 5/31/00 +0100, you wrote:
> > > >>On Wed, 31 May 2000 10:57:07 -0400, Jane Loyless wrote:
> > > >>
> > > >> >>You people are *not* talking about continuous usage, are you?
> > > >> >Pretty much so. Why not?
> > > >> >
> > > >> >since it went public last May. It may go out today, but after 18
> > months of
> > > >> >fairly continuous use, so far, so good.
> > > >>
> > > >>Same here, all my systems are running 24/7. I don't like waiting for
> > a system
> > > >>to bootup.
> > > >
> > > > Ack! I feel like a dork. I thought you were talking about
> > > > running on battery...
> >
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