User:Ccarrick/Power Generation


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The power generation talk during one of the Wednesday sessions of the Global Country Conference was helpful in gaining a sense of the current challenges for generating power for the XO. Take home messages are 1) human power generation is viable only if it can be sustained for 2 hrs or more, 2) grassroots options provide a lot of flexibility but are very location specific and 3) multi-battery chargers are incredibly helpful for charging XOs. Notes taken from the talk are below:

How much power does the XO consume?

Depends on state of XO
Max draw of 17 W
Not Charging
1 W idle
4-7 W Average
9 W peak, when using camera


Laptop off
1 hr 47 min at best
Laptop on
2 hrs 30 min

Battery good for 2000 cycles Off Grid Charging Options

Solar Panel
Durable amorphous silicon panels that can be rolled, though not the most efficient
5 W Panel
Charges with laptop off in 5 hrs 15 min
Not intended as a primary shipping device
7 W Panel
Charges with laptop off in 3 hrs 45 min
10 W Panel
Charges with laptop off in 2 hrs 40 min
Can be made into a solar blanket which folds into a compact shape as well, though this option is more expensive
60 W Solar blanket
Charging times highly dependent on weather
Charging times not linear- Doubling wattage doesn’t halve charge time since battery can only charge so quickly
Foot pedal
30 W output
Charges 2 batteries in 2 hrs using a 7ah lead acid battery
Costs $160- $200+
22 W, requires 2 hrs of constant cranking
Not viable until Gen 2
Grassroots efforts
Cow power- Arjun in charge of this
Wind, water, pedal, treadle
Freeplay currently working on water generator

Human Power Generation

Requires at least 1 hr and 47 min to charge a laptop
Can transfer power to a separate battery to recharge more than one laptop battery at a time

Multi-Battery Charger

Prototype available, hoping to get price below $300
300 W AC
Charges 15 batteries in 2 hrs
120 W DC
Requires 10-28 V input
Charges 8 batteries in 2 hrs
Can direct connect two 60 W solar blankets to charge batteries

Battery life

4 hrs during normal use
14-16 hrs in sleep mode

Helpful information for implementing power generation at a location

Climate & geography of area
Natural resources available
How many schools/kids/kids per class
Reliability of grid
Expected laptop usage
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