It is complicated. Voltage is not then only factor. There's also the internal resistance of the battery. So it depends on how much load a device poses and that depends on when the battery is measured. For example, load is much higher when device is transmitting than when it is receiving. And that load is higher than when only the CPU is running.   Measuring battery voltage with a multimeter is essentially measuring without load and doesn't take into account its resistance. If it measur