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measuring voltage of individual cells in 16s lithium battery pack.

The ADC Pi is an Analogue to Digital converter for the Raspberry Pi

12/04/2019

Posted by:
xsherlock

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Dear.

Can this module be used for measuring indiviual voltage in 48V lithium battery pack?

The concern I have is that all inputs have a common ground and in battery they wired in series so I should be measuring it on 2 wires on every single cell as there is no common ground.

How do I do that?

TIA

Maciej

12/04/2019

Posted by:
andrew

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Location:
United Kingdom

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Hello Maciej

Measuring the cells directly would not be possible as like you said they would all share a common ground through the ADC. You will need to isolate the ADC inputs from each cell using something like an isolated operational amplifier but that would mean that there is a constant current draw on each cell from the op-amps so they would discharge themselves over time.

A better option may be to use a dedicated battery monitor which is designed for monitoring and load-balancing multi-cell battery packs. Several manufacturers make battery monitor ICs that would work on a lithium battery pack. The BQ76PL455Afor example from Texas Instruments can monitor up to 16 cells and communicates over UART so it could be connected to a Raspberry Pi.

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