Hi, I am trying to build a sensor/meteorological station with the Udoo. However, the system will have to run "in the wild" on a battery which is charged with a solar panel. The station transmits sensor data via a 4G modem. The Udoo (quad) uses approx. 450mA when running without peripherals. This is far too much for my solar/battery powered system. Instead, I just wake up the Udoo every hour to read out the sensor data and transmit them to a webserver. So my question is what is the best way to put the Udoo to sleep for a certain interval and wake it up again. I tested Code: rtcwake -m mem -s 60 i.e. suspend to ram, off and disk mode are not supported. With rtcwake -m mem I managed to cut the power consumption to 85mA. In contrast, when the Udoo is turned off, the system/voltage regulator still consumes about 33mA. Ideally, I would like to get below 15mA but even less then 40mA would help me. Of course some external clock/timer could be used to cut the power but I would like to avoid that. 1) Is there a better way than rtcwake -m mem to put Udoo to sleep for a certain time with respect to power consumption? 2) Could the Arduino be used somehow? 3) What exactly is the battery connector J25 good for? Could I use it to connect a more efficient voltage regulator? 4) What is the required voltage range on the J25 battery connector? Thanks!