How do you measure the voltage - with multimeter on battery or what banana reports? If banana is powered from the battery then there is current flow in the wires from battery to banana. When there is current flow there is also voltage drop depending on how much current is used from battery and also how thick the wires are. So for accurate results use volt-meter and measure directly from battery contacts. Also there is non-linear relationship between battery voltage and how much energy is left. Depending on specific battery you should look at manufacturers discharge chart for various loads to know if there is problem. I would not worry too much about if you still get the runtime that is in line with the capacity of the battery.
Hello On my Banana PI infrared receiver is not detected at bootup. I'm running armbian 4.7 jessie. The only /dev/input device is that of axp20x-pekj, which I undestand to be a power controller. My issue is similar as found in this thread: http://forum.armbian.com/index.php/topic/475-bananapi-r1-no-infrared-device/ Except ofcourse the board is different From the other thread I gather I need to change something in regards to dtb-s, but I guess as the boards are different using the same one as mentioned is not a good idea.