jeffpk at gmail.com
Tue Jan 10 18:36:00 EST 2012
I wonder how a tablet really fits the Xo mission beyond PR?
The G1G1, while flawed in a few ways, made an attempt at least to put a
programmable machine in the hands of third world children and
empower them to be content creators.
A tablet is inherently a content consumer device, not a creator device.
This is the secret to Apple's success with them. (They have been
chasing this particular horse since the early Mac days. Mac was never
supposed to be a creator device, that was the ill fated Lisa.)
I cant imagine anyone typing much code on a touch screen keyboard. Is the
goal of OLPC now to create more consumers?
On Tue, Jan 10, 2012 at 6:28 PM, Richard A. Smith <richard at laptop.org>wrote:
> On 01/07/2012 06:40 PM, Alan Eliasen wrote:
> > I'm also curious about the power claims. What is its power
> > consumption and charging requirements?
> Its still much too early to lay out exact claims for this. These are A1
> prototypes. This is the stage where we start finding all the things that
> are using more power than we would like and try to reduce them. The exact
> size of the battery is also changing as we maximize the space in the
> battery cavities.
> We don't/won't start making any exact claims on power until it moves well
> into the B and C series builds.
> That said, a lot of the internals are almost identical to the 1.75 so the
> things I've previously said about 1.75 are going to be a good approximation
> of the XO-3. As John indicated the traditional display does consume more
> power than the Pixel-Qi.
> In case you missed my previous comment on 1.75 on devel@ the maximum
> runtime power draw of the 1.75 is 5W. (Not including the extra 5W you can
> draw from the USB port.)
> The power input front end of the XO-3 is currently identical to the
> XO-1.75 which matches the specifications of XO-1.5. 11V-25V input range
> and a maximum input rating of 25W. Unlike the XO-1.5 the XO-1.75 almost
> never gets to the 25W maximum because its runtime power is much lower. So
> the peak power draw only happens if its charging a very low battery.
> One difference between the XO-1.75 and XO-3 is that the XO-3 can _also_ be
> powered by USB On-The-Go (OTG). OTG has a strict 5V/7.5W power
> specification so charging via OTG will take longer. No. I've not yet
> measured how much longer. :) Sadly its not a nice linear thing that you can
> just do the math and figure out. There are many variables some of which
> will change with the next prototypes.
> Having a robust, wide voltage range, high power input is an important
> feature when using alternative power sources. Alternative power can be
> very unclean and very sporadic. You must be very forgiving on what you
> allow and when its available you want to maximize your input.
> I don't think any other tablet made so far would survive long term if you
> connected it directly up to an automotive 12V power system.
> > Has it actually been
> > demonstrated to be chargeable by "solar panels, hand cranks and other
> > alternative power sources?" Especially ones not requiring systems which
> > cost many times more than the price of the laptop, nor require someone
> > with the green skin color of the XO to crank.
> This claim isn't really new. Evey XO generation we have made to date
> matches this claim. In each generation we made an improvement over the
> Its always been possible to charge an XO from alternative power sources.
> There are sites in Rwanda, Peru, Haiti and the Solomon Islands (just to
> name a few) that are powered entirely by solar. These are using XO-1 and
> XO-1.5. Some of these use a more commercial type solar system and some
> just are just raw solar panels that connect directly to the XO.
> The XO-1 and XO-1.5 both had maximum runtime peak power draws in the 10W
> range. Running things like the camera activity which keeps the system busy
> would draw that power continuously. If you didn't have 10W of input you go
> backwards. Most people don't really realize how much work 10W of
> continuous power is. The physical size of a 10W solar panel isn't huge but
> its still pretty large and you need perfect solar conditions for that 10W.
> So what you really need is a 20W solar panel that so that a wide range of
> solar conditions still work. A 20W panel is pretty large and not something
> easy to lug around.
> The 1.75 (and tablet) have a runtime peak power draw in the 5W range and
> they idle even lower. So now devices that produce power in the 10W range
> can fully power the new XO devices in a variety of conditions. So you can
> envision taking an XO outside into the field connected to smaller solar
> panel (say 5-7W) and have a net power draw very close to zero. A 10W panel
> would almost certainly have a net draw of zero unless the solar conditions
> were really terrible.
> In my testing here in Boston I have powered a 1.75 directly (no battery)
> from the OLPC 10W panel in January sun. Here's a video Chris Ball and I
> shot Jan 9, 2012 showing a 1.75 completely powered by our 10W thin-film PV
> Hope this info helps,
> Richard A. Smith <richard at laptop.org>
> One Laptop per Child
> Devel mailing list
> Devel at lists.laptop.org
It's always darkest just before you are eaten by a grue.
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