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

Fri Mar 26 13:02:06 EST 2010

Andrew and Donna that all sounds promising and very generous 

will go off list if this goes any further but let me ask Andrew one more question here:  

 ... ie spell it out a bit more for me :) 

the targus powerpack you mention ... what is that exactly ? 

normal powerpack on laptop expects mains input of 240 V (AC)   - and delivers (according to the text on my powerpack) 19.5 V DC and up to 3.3 Amp  (usually much less current i guess)

so when i plug an inverter into say our car cigarette lighter, it takes 12 V DC, inverts and transforms to 240 V, which the powerpack changes back down to 19.5 V DC ... i can see how thats inefficient, (but ok as long as the car battery keeps charging)   

we can avoid some of these steps? -  your UPS 6.5 V batteries in series give 13V - wouldn't be quite 'close enough' to the required voltage of 19.5 V i would think?   these devices seem to be fussy about getting the right power? 

basic questions but i don't quite see how it works :) 

hoping though! 

re time frame, a few hours a day over a week would be good

Donna - i can't pretend an XO would have the right software, but i would love to have a play with Sugar on the real deal- would be very cool

rob    

-----Original Message-----
From: yr7-10it-bounces at edulists.com.au on behalf of WEIR Andrew
Sent: Fri 3/26/2010 9:55 AM
To: Year 7 - 10 Information Technology Teachers' Mailing List
Subject: RE: [Yr7-10it] charging laptop off solar etc? 

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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http://www.edulists.com.au - FAQ, resources, subscribe, unsubscribe
Year 7 - 10 IT Mailing List kindly supported by
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http://www.vitta.org.au  - VITTA Victorian Information Technology
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Year 7 - 10 IT Mailing List kindly supported by
http://www.vcaa.vic.edu.au - Victorian Curriculum and Assessment Authority and
http://www.vitta.org.au  - VITTA Victorian Information Technology Teachers Association Inc

Important - This email and any attachments may be confidential. If received in error, please contact us and delete all copies. Before opening or using attachments check them for viruses and defects. Regardless of any loss, damage or consequence, whether caused by the negligence of the sender or not, resulting directly or indirectly from the use of any attached files our liability is limited to resupplying any affected attachments. Any representations or opinions expressed are those of the individual sender, and not necessarily those of the Department of Education and Early Childhood Development.