Screen-off vs. turn-off : what's the different in terms of batt life?

[johnmnemonic]

Since the machine is not really shutdown when 'turned off' unlike the desktop counterpart.

I'm just wondering how much batt can u save when u turn it off compare to screen-off-only.

[Kacey Green]

several percentage points per hour, because when you turn off the screen the device is still running at normal power usage, but when you press "power" the powermanagement features go into effect (all the different sleep modes and such)

[WyattEarp]

I don't know how much power you will save but screens use a good amount of power especially when lit. From personal experience when playing music with the screen off saves me about 5-10% of power drain per hour of use. Thats my best estimate without a formal test.

[Kacey Green]

you can save even more in either mode by turning off "receive all beams"

[bimmergirl]

sorry for my ignorant but how do you "screen off" ?

[Kacey Green]

There are several ways to do this, the only one I can think of right now is in Windows Media Player, you set a hardware button to turn the screen off and on again, if you have WMP set to respond to keys when it isn't the active program you can do this during any program

[Kowalski]

i get 4 hours of runtime with full brightness and 6-7 hours with screen off
so this shows that screen is evil :devilboy:

[johnmnemonic]

I'm just curious that: when you turn off the device. Is the cpu still running at 400 Mhz? Or not running at all until the next power-on.

[Kacey Green]

it is running in one of its sleep modes during this time, until the device goes in to a higher sleep mode (to check for alarms, midnight maint. etc) then device and processor go back to one of their more fully sleeping modes. When you get the turning off to conserve battery power message, I think that is the closest to off as the device gets without loosing data.

Edit: I don't know if sleep modes are measured in Mhz, Khz, hz, mhz (milihertz), or not in cycles at all

[Kowalski]

if a proccessor is totally shut down the only way to wake up is sending reset signal.
but in the sleep mode there are some other ways to wake up the proccessor but in these modes some parts of the cpu still consumes power.