Zaurus Power Usage & Battery Drain

[mathemajikian]

Test results by an OpenBSD/Zaurus user concerning power usage and battery drain:

arm,

I did some tests to see the power drain on the battery and I found
some interesting things.
I put a 4V power supply on the battery terminals and measured the
current my SL-C3200 Zaurus drew.

Here are some of the highlights:
* When powered on, the ZHost USB host cable (short, white mini USB
plug) simply plugged in (no usb device attached) draws an additional
85mA of current.
* If you have the Zaurus in low power mode (apm -L) and you put it to
sleep (zzz) then when it is woken up it is in high power mode but apm
reports that it is still in low power mode. (this sounds like a bug)
* OpenBSD suspend takes 18mA compared to Linux suspend takes only 2mA
of current.
* suspend and standby both draw 18mA
* after shutdown and pressing the reset button the Zaurus draws only 1mA


Full report, voltage level at 4 volts in OpenBSD:
(zaurus in high power mode)
*running X in xterm, idle, 234mA
*executing yes command, 394mA
*executing find /, 600mA
*idle and HardDrive spinning, 295mA
*executed xmms and playing mp3, varies between 370mA and 410mA
*executing glxgears, 370mA
*executed shutdown -hp, 18mA
*then pressed reset button, 1.2mA

(zaurus now in low power mode)
*executed apm -L now idle is 195mA
*screen turned off, 170mA
*CF card inserted, 216mA
*CF card mounted, 196mA
*executed zzz, 18mA
*after wake up from zzz, 234mA (this looks like high power mode even
though apm says it is in low power mode.  I had to do apm -H; amp -L
to put it back in low power mode after sleep)

Notes:
It seems that the Zaurus lowers the current usage when increasing the
voltage.  I plotted out a graph of this and found that at 3.7V it was
drawing 280mA and at 5V it was drawing 200mA and at 6V it was drawing
180mA.  The graph basically leveled off at 180mA when the voltage
reached 5.6V or more.  Also I found that there are differences in
OpenBSD and in linux (db mode) when apm --suspend is executed the
Zaurus draws 2mA and after shutdown -h it draws 39mA.

-alfred

[Gatu]

Test results by an OpenBSD/Zaurus user concerning power usage and battery drain:

arm,

Notes:
It seems that the Zaurus lowers the current usage when increasing the
voltage.  I plotted out a graph of this and found that at 3.7V it was
drawing 280mA and at 5V it was drawing 200mA and at 6V it was drawing
180mA.  The graph basically leveled off at 180mA when the voltage
reached 5.6V or more.  Also I found that there are differences in
OpenBSD and in linux (db mode) when apm --suspend is executed the
Zaurus draws 2mA and after shutdown -h it draws 39mA.

-alfred

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This behaviour is typical for devices which have a switching power regulator.
As this is the most effective way of converting and stabilizing voltages (almost no heat dissipated which would mean loss of energy), I guess that this kind of voltage stabilizator is very common in this kind of devices.

Br,
Gatu