harvesting energy

Ed McNierney ed at laptop.org
Thu Oct 27 14:38:49 EDT 2011

Tony -

Due to our battery-management system, it is impossible to charge an XO laptop in less than about 110 minutes.  With a few breaks, I have personally fully charged an XO-1 laptop with a Freeplay hand crank charger in 110 minutes, and I am by no means "an adult athlete", especially when it comes to arm strength (I can generate a few hundred watts on a bicycle, however).  You're going to have to take my word for it, because I'm not going to do it again...

It sounds like what you saw may have been more a demonstration of an extremely inefficient charging system, which should be a reminder as to how very easy it is to set one of those up!

	- Ed

On Oct 27, 2011, at 2:14 PM, Tony Anderson wrote:

> Has anyone estimated the work required to charge an XO? Mike Lee gave a demo some time back at the Washington D.C. Learner's Club which seemed to show that it would be a difficult workload for an adult athlete to charge a laptop.
> Tony
> On 10/27/2011 12:00 PM, devel-request at lists.laptop.org wrote:
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>>    1. Re: harvesting energy (Chris Leonard)
>> ----------------------------------------------------------------------
>> Message: 1
>> Date: Thu, 27 Oct 2011 11:51:02 -0400
>> From: Chris Leonard<cjlhomeaddress at gmail.com>
>> To: Kristen Eisenberg<kristen.eisenberg at yahoo.com>
>> Cc: "devel at lists.laptop.org"<devel at lists.laptop.org>
>> Subject: Re: harvesting energy
>> Message-ID:
>> 	<CAHdAatb59OU2jiZ=aKBOff2jofq0QNS9n16YjUub169KrTWsjg at mail.gmail.com>
>> Content-Type: text/plain; charset="iso-8859-1"
>> On Thu, Oct 27, 2011 at 7:23 AM, Kristen Eisenberg<
>> kristen.eisenberg at yahoo.com>  wrote:
>>> If we're talking about kids powering their own devices, I think the
>>> way to go is to turn "work" into play. The merry go round/hard bar
>>> swing would fit in this category.
>>> So basically, let's look at activities where energy exerted is ambient
>>> anyway? What I mean is that the energy is being used up by the kids
>>> anyway, so why not tap into those. An example is to give them some
>>> variant of those "dance straps" meant to power cellphones before they
>>> go off to run and play during recess and lunch break.
>>> One way to tap into this would be to create new playground
>>> installation toys which can be used for harvesting energy.
>>> Q: how much abuse can a kinetic energy harvester withstand? A soccer
>>> of basketball has a lot of kinetic and impact energy bouncing around.
>>> I'd imagine that's too much abuse though, and whatever harvesting
>>> mechanism would break from the forces.
>>> Would piezo work there?
>> FYI, this is exactly the concept behind PlayPumps for water pumping.
>> http://www.playpumps.co.za/
>> cjl
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