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One Laptop per Child

One Laptop per Child. One Laptop per Child. Laptop Power November 18, 2008. Challenges. Supplying power can be a large and difficult challenge in a deployment. Even in areas with a power grid Lack of an established grid increased the difficulty significantly

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One Laptop per Child

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  1. One Laptop per Child One Laptop per Child Laptop Power November 18, 2008

  2. Challenges • Supplying power can be a large and difficult challenge in a deployment. Even in areas with a power grid • Lack of an established grid increased the difficulty significantly • No recipe solutions. Each site is unique

  3. How Much Power? • 2 Primary modes of laptop operation • Charging battery • Not charging • Charging battery • Max draw of 21 Watts • Closer to 26 W w. power factor correction • Not charging • Less than 1 Watt in sleep mode • Average of 4 – 7 Watts while running w. peaks up to 9W

  4. How Much Time to Charge ? • Fastest with the Laptop off: • All power used to charge battery • 1 hour 46 Minutes • Laptop on: • Excess power used to charge battery • About 2 and half hours

  5. Individual solar panels • Assuming maximum output (full sun)‏ • With the laptopoff • 5W charges laptop in 5 hours 15 minutes • 7W charges laptop in 3 hours 45 minutes • 10W charges laptop in 2 hours 40 minutes

  6. Alternative Power Sources • Individual Solar • 10 Watt solar panels • Only for smallest schools • Centralized Solar • High initial cost • Large solar panel arrays and charge ctlrs. • Some battery storage required • Inverters to minimize distribution costs

  7. Alternative Power Sources • Crank • Still needs 2 hours of cranking. • Not viable with existing XO laptop • Weza • Approx 30 Watt output • 7Ah Lead Acid battery • Will charge 2 laptop batteries in 2 hrs. • Grass Roots • Cow power • Water, Wind, Pedal,Treadle

  8. Multi-Battery Charger • Charges 15 batteries in 2 hours • 300 Watt AC • 120 Watt DC option (10 – 28 Volt input)‏ • 8 Batteries in 2 hours • Direct connection to 2 x 60W solar blanket(s)‏ • Available in Q1 2009

  9. Power Management Available today: • Hardware ready for suspend/resume • Current stable builds have support for sleep on lid close or button • About 4 hours of battery life during normal use • 14-16 hours of battery life in sleep mode • New “Extreme” power savings mode + additional power savings in sleep for non-mesh. (40+ hours of life in sleep)‏

  10. Deployment Planning • Deployment Location Information • Information needed • How many schools, how many kids, and how many kids per school ? • How many school off power grid ? • How many hours of usage daily ? • What is the climate and geography of deployment areas ? • What natural resources are available ?

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