I would like to use Nanos G20 as a mobile webcam to upload picture once an hour to internet. For power using 12 V, 6 Ah battery -> Traco Power switching regulator = 5V. Measured power consumption from mains 0.8 W only Nanos 1.6 W with webcam 2.4 W with Huawei and webcam So battery would last only for one day continuous operation. Tried power saving http://www.armbedded.eu/node/372 echo "" > /sys/class/rtc/rtc0/wakealarm echo "+20" > /sys/class/rtc/rtc0/wakealarm echo mem > /sys/power/state 1) works with NanosG20 and LogitechC510 webcam. Power use 0 W from mains. 2) Does not work with Huavei E1750 surf stick. Power consumed during power down = 1 W. 3) Does not work with RTL8187 stick. Power consumed with power down = 1.3W. May be there is still some software method? or I could try in hardware to switch off USB 5 V power with GPIO and external transistor. You can toggle pin PA27 to switch off the 5V supply for USB (low is on, high is off). You can use this method to do it: http://armbedded.eu/node/258 Thanks a lot for supprt! Very smart feature! Will print out and study Nanos schematics. This controls USB power: echo 59 > /sys/class/gpio/export echo out > /sys/class/gpio/gpio59/direction echo 0 > /sys/class/gpio/gpio59/value # +5V on echo 1 > /sys/class/gpio/gpio59/value # +5V off The value is not preserved after restart, but it is not a problem to set it every time. 4) power saving works with nanos and Edimax wlan stick. 0W. But need to connect to network again iwconfig wlan0 essid "WLAN" dhclient wlan0 otherwice very fast 5) does not work with rtl8188. Power consumed in power down mode 0.7 W after power back need to wait ca 1 min ADDRCONF(NETDEV_UP): wlan1: link is not ready /etc/init.d/networking restart iwconfig wlan1 essid "WLAN" dhclient wlan1 then works ------------------------------------------------------------------------ 5V switching down-converters comparison Traco Power TEN 10-1211 in 9-18V out 5 V 2A 25 mA idle Fortec Electronik Ascheim 9-18V 5V 1A 14 mA idel Power trends 30 V in 5V 1.5A idle 5.5 mA LOWEST CURRENT CONSUMPTION. Bet to use with 12V battery to supply NanosG20. aimtec AMSR-7805Z 6-32V 5V 0.5A 6.5 mA idle