Hello Tom.

03 Sep 03 12:24, you wrote to me:

 TW> Well lets do soem Simple math. Since you have a minimum computer I was
 TW> estimating 75 Wattsas a requirement. At 12 Volts that figures out to
 TW> 6.25 Amps.

That is way too high.  How about less then 5W for the computer and let us
be generous and give the display 20W (tft btw).  No keyboard but a USB
pointing device instead that can be controlled by mouth.  Let us add that
to the computer itself and even it out to 5W.  Add to this a pcmcia
wireless card.  Offhand I don't know what they consume but as long as we're
being generous let's throw in another 5W.  That should be about right but
feel free to tack in a few extra watts to add some comfort.  Besides, the
power supply I currently have is limited to 40W so I better not tack in too
much more and probably should think about limiting the display.  I have
some ideas there but right now I am not too sure.  If needed I could bump
the power supply to 75W but for this first experiment 40W is the maximum. 
I have to work with what I've got.

 TW>  What is your estimation of Averqage hours use per day??

How about 24 hours a day and seven days a week?  Give the display maybe
8-10 hours a day, again to be generous.  I'll use the apm to power down the
monitor when not in use.

 TW>  What is the rating of yuor Gel Cells.

I'll let you know as soon as I know.  I only got the one here right now and
just looked to see if there are any specs on it.  Tons of information there
but nothing much of any use to this particular problem.  They were given to
me to see if I could get something going with respect to a quadrapalegic's
wheelchair.  His needs for an onboard computer would be far less then
24h-7d but what the heck.  I want to know exactly how long it will run for
all on it's own.  Call me curious.

 TW> Adn incideltly a Gell Cell is a Poor Battery to pick fro a possable
 TW> deep discharge operation. A Wet Cell is far better suited.

Cool.  I'll keep that in mind but I already have the gel ones so until
those see their last days I doubt I'll be buying for a spell.  Besides, the
powered wheelchair already has two brand new gels installed so I thought it
would be best to duplicate that.  Add to that the fact that most boats
around here also employ gel batteries and if I add them into my target
audience then I'd be better off following suit.  For boats I am thinking
high resolution moving maps for GPS.  Heck, might even throw in a fish
finder just for fun.  Fun is good.

 TW> Incideltly I had the same thoughts as you. But I picked a Laptop as
 TW> the Computer and use a 205 Ah Reserve capacity Size 31 Deep Discharge
 TW> rated Wet Cell for my Battery. That calculates into nominaly 225
 TW> Continious operating Hours before recharging.  :-)  :-)

Not too shabby.  I plan to beat that.  Mind you I gave up on laptops as
being useful way back when. An overpriced toy methinks.  Given your specs
and what I have seen about laptops I feel confident that I could easily
double your uptime without trying too hard.  Yes even with the gel.

The CPU can be clocked to 133MHz but to be honest for our purposes that is
overkill.  But what the heck.  Use it or lose it I say.

No Windows btw, as it runs the CPU at 100% whether the CPU is in use or
not.  I like NASA's idea of using Linux on satellites as it can be used to
control the CPU's usage to a minimum.  They claim it keeps the CPU cooler
and extends the life.  Sounds like a good idea to me.  Also no CD-ROMS,
DVD-ROMS, fans, or any other spinney things that would further drain power.
 HD is a solidstate flash disk which requires spit for power so that will
be an extremely minor drain.  Besides the plan is to just read a compressed
ramdisk off the disk so there shouldn't be a need to do too many
read/writes other then to RAM.  So far I found that 32M works fine but 64M
gives us more breathing space.

I think that covers it for now.  What do you think?  You obviously know
what you're talking about and we definetly could use the input.  With or
without help we plan to make this a reality so don't feel that you must but
it won't hurt my feelings any if you want to take charge.  I am not that
much of a control freak and am always willing to listen to solid advice.  I
might argue with it though.  I've been known to do that.  :-)

I am confident that this is an attainable goal.  I'm closing in on it.  I
can taste it.

Maurice

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