Simple measuring of battery voltage

Experience the very same issue with reading values from resistive touch screen. The internal pull-up/down resistors are about 30..40K which may need to be considered when measuring - because they can pose 'significant load' on the measured 'object' - depending on circuitry. In my case, I could not detect the 'OFF' state reliably... continuous reading/sampling without pull-up/down even triggered subsequent setWatch() on the open pin - something did not expect. The solution is to pull down - and if the the 30..40K are a significant factor - switch to open input before reading (see http://forum.espruino.com/comments/11892­295/). It is anyway a good thing to have the input as much open as possible to not waste any power. On the other hand to avoid floating, you may consider to pull down externally with a resistor of much higher value - 470K...1M and keep it... (value all depends on your circuitry). In my case it did not really matter 30..40K vs 300..400 Ohms, and left it pulled down.