[Yr7-10it] charging laptop off solar etc?

[WEIR Andrew]

Rob,
I must agree with Tony in the inefficiencies issues mentioned but I will
add one thing.

What Time frame are you looking at working remotely for??

I frequently have to run a Laptop, Two Way Radio and Packet Modem from
battery. I managed to source my self 2 pairs of 6 volt 135 A/H
batteries. (Removed from a UPS after two years) When these are connected
appropriately I have my 12 volts for running radio modem and laptop
power packs. 
I have had about 3.5 days of 8 -10 hours a day. Laptop Is always running
but modem and radio transmit about 10 secs every min. 

This is laptop running through Targus portable power pack. Radio is
12volts naturally and modem run of usb power on laptop.

This is with no solar panel at all.

I have learnt the following, 
1. Use a Portable power supply not a 12V/240V inverter running the
laptops normal power pack.
2. Power Management is important. Lower Processor speed longer life.
3. Make sure your source battery's are as charged as possible. 


Anyway happy to talk further and if push comes to shove contact me of
list, can possibly arrange to lend you the second pair of batteries I
have.


Regards
Andrew Weir
VK3HFT



Andrew Weir

Information Technology Co-ordinator 

Thomas Carr College

-----Original Message-----
From: yr7-10it-bounces at edulists.com.au
[mailto:yr7-10it-bounces at edulists.com.au] On Behalf Of Costello, Rob R
Sent: Friday, 26 March 2010 9:31 AM
To: Year 7 - 10 Information Technology Teachers' Mailing List
Subject: RE: [Yr7-10it] charging laptop off solar etc? 

Hi Tony

thought you might have some ideas on this

i know the XO is designed for this but not a feasible solution in my
case :)

i take your point on efficiencies - the steps in converting to AC and
back to DC etc

sounds like still harder than i hoped

might need to look at generator

thanks

Rob


-----Original Message-----
From: yr7-10it-bounces at edulists.com.au on behalf of
forster at ozonline.com.au
Sent: Thu 3/25/2010 10:40 PM
To: yr7-10it at edulists.com.au
Subject: Re: [Yr7-10it] charging laptop off solar etc?

> hello all
>
> anyone know any good shelf solutions for charging laptops from solar
etc?
>
>   (for extended usage over several days at location with no power)
>
> is adapter off  lead acid battery (ie stand alone car battery?)  a
possible solution? - i know it works in car but not sure how it would
last without recharging - instinct says laptop is a trickle feed so
should be ok if battery was in good nic?

You will get 2-4 hours out of a car battery. A solar panel produces
approximately the equivalent of 4 hours a day at its rated power so you
would need quite a big panel.

All the efficiencies multiply, panel x battery x inverter x laptop
charger x laptop battery so if each was 80% efficient theres still not
much left at the end.

Need aggressive power management, minimum hard drive time, minimum
backlight etc. A netbook might be lower power. The OLPC XO laptop has
been designed specifically for this application.

Tony
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