I am currently developing a circuit to meter liquid level among a few other things and it will have a backup 9v Battery. I want to be able to meter the battery using an analog pin, but I do not want to connect it directly through a voltage divider as this may represent a constant draw on the battery(am I wrong about this?). So I developed the circuit below.
Sig In represents a digital pin being set high, and Sig Out represents 1/2 of the 9v battery’s current voltage. I used the 47K resistors as they are already on my parts list and they seemed sufficient.
Anyone out there notice any glaring issues here, or have anything they could add? I’m looking to have PCBs made soon and this is one of the last things I need to work out.