Suppose I want to measure individual cell voltage of a 12-serial-cell battery pack, what would be my most economical options?
Single cell voltage is 3V-4.2V but the stack can be between 2-12 cells high.
I am looking for a solution to be attached to a microcontroller running at 3V3. Update rate requirement is modest in the range of 10Hz for the whole stack.
My first bet would be a instrumentation amplifier with sufficiently high common mode range multiplexed to the respective junctions between the cells. This however requires both a sufficiently high rated amplifier and multiplexer. Can someone suggest suitable parts or suggest a better approach?
By the way, the cell voltage of course needs to be sampled by an ADC but resolution needs to be modest 8-bit at most.
Best Answer
There are off-the-shelf solutions to this problem, you don't need to mess with transformers and exotic circuits. You can take advantage of the fact that it's much easier to isolate a digital signal than an analog signal and use serial communications between your microcontroller and the battery monitor. You should search for a "multicell battery stack monitor". As an example, the Linear Technology LTC6802 can monitor the voltages on up to 12 Li-ion cells and provide the voltage data via an SPI interface.