XO power data: power draws for plugged-in laptops

Guest post by Richard Smith

We’ve finished testing power consumption while plugged into a 230V ac wall outlet for the XO-1 and the XO-1.5. The new machine performs well while suspended, and suspends very smoothly.   The 1.5 charges faster and using less power to charge the same battery.  It also draws slightly more power when in high use, thanks to its variable CPU.

See the chart below, which includes the power draw of the AC adapter.  Battery-only numbers will be significantly lower, in particular for idle and suspend, but are a bit harder to measure cleanly.  There is no comparison chart for that yet.

Power draw at the wall (XO + adapter + backlight)

Scenario XO-1 XO-1.5
Full charge 56 Wh 47 Wh
Idle 8.5W 7.2W
High 9.5W 9.7W
Suspend 5.2W 2.85W
  • Full Charge: The amount of energy it takes to completely charge a dead battery, using an adapter (power needed for bulk charging of batteries may differ).
  • Idle: Laptop sitting at the Sugar home screen, with power management disabled, backlight on full, charging.
  • High: Laptop running the Record activity’s “preview” mode.  Power management disabled, backlight on full, charging.
  • Suspend: Laptop with power management enabled, suspended, charging.

Calculating low-power options:

  • The backlight draws close to 1W – you can shave that off of the idle and high numbers turning it off.
  • Most of the power draw on suspend is to the adapter – you could view that as an upper bound on how much to factor out of the other numbers for battery-only power usage.

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