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Stack of batteries through ADC: Is this possible?

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NVergunst

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So I have an arbitrarily large or small amount of batteries that are stacked in series to give potentially large pack voltages.

I would like to monitor the voltage of each cell individually and accurately. My latest idea is to make an isolated power supply from a source not from the batteries. Then there will be lots of relays (solid state hopefully) that can switch each cell's positive and negative terminal. The negative of the cell would connect to the negative of the isolated supply, and the positive of the cell would go through some goo and into an ADC. The results fed over an isolated channel digitally.

My question is, is it possible to attach the negative of the battery cell (which might be at 100v relative to the bottom-most cell stack) to the negative of the isolated supply as long as no other cell's negative is attached either? Obviously there would be dead time between switching the cells to assure only 1 cell is ever connected at one time. Then to read all cells, I just switch different pairs of relays.

Are there any adverse effects of this? My backup plan is to put little buck-boosts on each cell that then power the ADC and isolation channels but I would rather put the power load on the system reading it and have just one transformer smps instead of multiple independent smps.

Is it ok to connect the negative of the cell to the ground part of the isolated power supply so that the ADC and the cell are both referenced to the same ground?
 

allanvv

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There's special battery pack monitoring IC's that would be ideal for your application.

Something like this: **broken link removed**
 

NVergunst

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There's special battery pack monitoring IC's that would be ideal for your application.

Something like this: **broken link removed**

Yes i know, but I do not want to use them. I would use the Linear LTC6803 if I were to use one.

I would rather do it manually as there is a greater plan behind it. I just want to make sure tieing the grounds together wont do anything funky.
 

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