[OLPC India] charging XOs using bicycles

[Arjun Sarwal]

Holden,

The XO's charging circuit takes input voltages ranging from approx 11V
to 18V. These are governed by the EC's behavior that in turn controls
the charging of the batteries.

A while ago, I along with Richard did some approximate calculations
and as a rule of thumb , you'd need to give the XO about 1A @12V for a
little more than an hour to charge it completely.

This means your generator (bike dynamo in this case) would need to
supply approx 12W for an hour. I've found bicycle dynamos to usually
generate much less power, more in the range of 1-4W.

This doesn't by any means imply that I am discouraging the development
of alternative power solutions; I very much would like to see more and
more indegenuous power solutions being tried out.

(Richard: please correct me if I have been wrong on any of the
charging details, I will make sure to put the details down somewhere
on the wiki this time)

thanks
Arjun

On Sun, Apr 27, 2008 at 10:12 AM, Holden Bonwit <hbonwit04 at yahoo.com> wrote:
> For the power from bicycles, I was originally thinking the standard AC
> bottle dynamo into a rectifier into the laptop, but now am considering a 12
> V battery in the middle.  Charge the battery from the bicycle, then charge
> the laptop from the battery.  What do you think the best route is?
>
> Did you get my comments about charging voltage (up to 25 V, and higher is
> better)?
>
>


-- 
Arjun Sarwal
Intern, One Laptop per Child
Email: arjun at laptop.org
IRC: arjs on irc.freenode.net in #olpc, #olpc-health, #sugar
Skype: arjunsarwal85