[OLPC-AU] XO-1.75 relative performance

Richard A. Smith richard at laptop.org
Wed Nov 2 01:35:51 EDT 2011

On 11/01/2011 08:54 PM, C. Scott Ananian wrote:
> the online benchmarks will probably be Android-based, and won't tell
> you anything about battery life and power consumption, where OLPC has
> put its focus and made great improvements.)

I suppose Its probably time to start throwing out some worst case 
battery life numbers.  We have built enough revs of the 1.75 now that 
the works case numbers aren't going to change.

My battery logs show that the minimum useful Wh we get out of our 
battery is 18Wh.  Fully loaded I've yet to see the XO-1.75 draw more 
than 5W [1].  So 18Wh/5W is 3.6h.  I feel safe in saying that regardless 
of what you do on the 1.75 you are going to get 3.5 hours of battery 
life. Period.  Thats a lot better than the worst case values of 1.5 
which was difficult to pin down.

Since suspend/resume is still undergoing heavy development I don't have 
any good estimates yet for user based workloads but early indicators 
look promising.  In the coming weeks I'll get some good numbers.

An interesting data point is that the 1.75 is the first laptop of the XO 
series that has ran 100% from a solar panel for an extended period. 
During my solar testing I often swap in different batteries.  The 1.75 
can consistently survive battery removal under moderate solar conditions 
when connected to the OLPC 10W solar panel.

[1] Excluding connecting an external USB device drawing full power which 
would be an extra 5W.

Richard A. Smith  <richard at laptop.org>
One Laptop per Child

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