Hi Everyone, Hopefully someone with a bit more experience on linear op-amps can help me here. The problem is the controller I have has common ground across all the analog inputs but I want to measure the "voltage difference" between multiple points in a battery bank circuit. To do this, I need to isolate the source voltage and match it to the 5v analog input. The source voltage across all the points is below 5V which is what the analog controller can read. eg: <-- Gnd Battery here < 5v <-- measure voltage here for analog input 0. This is gnd for analog input 1. Battery here < 5v <-- measure voltage here for analog input 1. This is gnd for analog input 2. Battery here <5v <-- measure voltage here for analog input 2. And so on for 21 batteries (21S) Obviously the easy way is to do a simple voltage divider. The problem with this is the resolution decreases in line with the number of batteries you have. Needs to be within 0.03 resolution. I've been doing a bit of research and it seems I need a linear Op Amp on each battery input to isolate the ground and just feed the differential voltage to the analog input of the mcu. In comes the LM324 (Quad linear op amp) : http://www.jaycar.com.au/products_uploaded/ZL3324.pdf I think I need to use the "Non-inverting DC Gain" schematic (Page 9) or the "Voltage Follower" so that the input voltage matches the output voltage. Which one of these Is this the right schematic? As mentioned, the Vin (to chip) is 5V and I want to measure a range of 3-5V on the inputs. Is there a better linear op amp I should be looking at? Thanks in advance!