[SPARCbook] Huge Battery

[Ian Spray]

On 21-Nov-00 Matt Evans wrote:
> 
> The Tadpole lore speaks of a huge external battery pack that has 4-6
> hours of life in it.
> 
There was indeed one, which worked on S3 machines up to the S3TX, but not
the S3000.

> This would be cool, it would border on making the sparcbook a useable
> laptop, as opposed to a portable sparc.
> 
Hmm, maybe.  I tried one once (which has since died), and it was *heavy*. 
I think it had D cell NiCd's in it, which gave it the Ah, but cost in
portability, especially as it sat along the back of the machine, making it
very hinge heavy.

> Does anyone have such a beast ?  Has anyone seen one ?  Is the battery
> life really that good (and if so, is it sustainable after many recharges
> ?).
>
Pass - the one I had ran for 10 minutes max. as all the cells were in a
very bad state, and then case wasn't much better.  I'm not even sure about
re-celling them as I think there was a controller chip in the pack which
talked to the microcontroller.

> I'm wondering how much of a pain it'd be to have a battery custom
> fabricated for the thing for massive battery life.  Maybe a huge battery
> that the tadpole sort of clipped onto.. i.e the battery was the entire
> bottom panel... so it just adds thickness to the unit but not in any
> other dimension.  And it'd help keep your lap nice and toasty, just like
> the normal tadpole :)
>
Bear in mind that under heavy CPU loads the base of the unit is used as a
heat sink.

> What are the electrical specs of the tadpole battery connector ?  What
> makes a long running battery at a given voltage/current requirement ?
> 
Is it in the Tech. PDF ?  There are voltage in (!) and data lines which
talk to the microcontroller so that the external DC can be used to charge
the internal and/or external packs (and switch from one to the other
automatically when one is full).

Personally, I've only ever used a Yuasa 12V 7Ah lead gel cell connected to
the DC in connector, which gives me hours of run time.  It's not really
portable (and heavier than the D cells), but it does have the advantage of
being beefy enough to recharge the internal battery, which acts as my 'final
warning' time to shut the machine down.


-- 
Ian Spray          :  Software Engineer     :  Tadpole-RDI
iws at tadpole.co.uk  :  +44 (0) 1223 428 224  :  http://www.tadpole.com/