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
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
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
Location:
United Kingdom
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.
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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