I did some experiments with a battery/solar powered Linksys BEFW11S4 a while
back and found that it used about 900mA (or 0.9 Amps) at 12 Volts into a
DC-AC power inverter.  (Very inefficient - but fit the experiment with
entirely off-the-shelf products.)

But these numbers aren't fully accurate either.  Ideally, you would run
direct DC to the access point.

You are right about P = I * E and your assumption of the answer.  But as you
said, the power capacity of the DC supply is not the actual power *draw* of
the access point.

-Mike

--
Mike Outmesguine
TransStellar, Inc.

  ** Complete Technology Services **

www.TransStellar.com



-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf
Of Aaron Markham
Sent: Tuesday, June 17, 2003 4:21 PM
To: [EMAIL PROTECTED]
Subject: Re: [SOCALWUG] Low Power AP's using solar



> 
> P.S. - Just curious what kind of overall power
> consumption (in Watts)
> you seeing for APs? Overall AP power needs should
> NOT really be so high that a small solar panel
> couldn't handle it.
> 

Well I don't really know power calculations... maybe
someone can provide a link for that?  I vaguely
remember this stuff from school, but now that I
actually can use it, I'm not sure how to do it.

This is what I've been reading:

P = I * E
watts = amps * volts ???

so if the AP's power plug says 5V and 2A...

5.0V * 2.0A = 10.0 watts

I re-read the plug and I see that the above numbers
are the plug's output, so I don't think those are the
right numbers to work with.  The input is 0.5 amps and
100-120 volts.  In that case we're looking at 50-60
watts.  I don't like that number cuz now my power
requirement just went up 5 fold.  

Aside from the watts calculations, looking at the
solar panels it seems that to get 2 amps (0.5A * 2
AP's = 1 amp plus the extra required to charge up the
battery to last all night) you'd need at least a 30
watt panel, but I'm just guessing here.  This page has
some good power stats:
http://www.seslogic.com/solarex.html

If anyone can shed some light on this calculation it
would be appreciated!

Thanks,
Aaron

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