“Following on from yesterday’s post about Eo battery issues, it was nice to wake up and see that Mgadget found out something interesting!
“We had identified two issues:
1 – Why are Eo’s appearing to drain more power than a 1.5ghz laptop with 12″ screen? (18 watts)
2 – Why arent we seeing the processor drop into power saving modes at idle.
We’ve identified the cause of the bad idle battery life. Its a known USB and power-saving bug. (USB devices get polled and the CPU never gets a chance to go into power-saving C3 state.) The Wifi and SD card slot are actually USB devices (I guess this saves developement costs and makes motherboards more generic.) and you have to disable the whole USB bus before the power-saving modes are reached. Of course, this is not a practical solution. However, it proves that there’s a fault there. We’re hoping that this could be fixed with a BIOS or even driver updates.
We’re still waiting for some more Eo battery life tests (with USB bus off) to determine the exact advantage of turning the USB bus off. (It looks like it will increase idle/low-power battery life by 30% though which is very significant.)
The second issue – overall power drain – is still being queried and tested. I’m not aware that Tablet Kiosk have given any feedback on the ticket raised yet and I know that no-one has done the battery drain measurements and screen-off performance testing.”
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