ADC reading within a series circuit suggestions

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1

Hello fellow Arduionoers!

I have built a great LiFEPO4 battery MONITORING system (for my own use on my bike battery pack) using a few Atmega 328s. It currently takes a reading of one cell and also a voltage divided reading of the whole pack, makes comparisons, etc. I would like to expand on this and take voltage readings of every cell in the series without having to use voltage dividers on each line. Microcontrollers reference the ADCs only to ground as far as I can tell. Does anyone have any ideas on how I could accomplish this? Perhaps a particular external ADC multiplexed? (Ultimately, I will have a large number to read, so I’ll be muxing them anyway.) Thanks in advance for your creative answers.

2

How many cells total? A differential amplifier and differential mux could do it up to a certain voltage level. Beyond that, there was a very clever method proposed in an earlier thread that used a simple voltage to current converter for each cell when the common mode voltage was up around 50V+

3

It’s currently 16 cells at 48V total nominal voltage. However, I’d like to figure out a way to do this up to 300ish volts (modern electric vehicle voltages.)

4

Look at this thread: https://forum.sparkfun.com/viewtopic.ph … ultiplexer rrpilot had a great idea that scales very well.

5

Perfect. THANK YOU!