Measuring multiple batteries without a common ground

Other Hardware Sensors
21

dougp:
I'm probably out of my depth here but, could this work? Essentially, mount a voltmeter for each cell and read them through I2C.

I have imagined a solution using 12 lilypads, one on each battery, but then you have got the problem of transmitting the result in an isolated way.
No, finally the capacitor-relays solution is probably the best way to go.

22

RIN67630:
I have imagined a solution using 12 lilypads, one on each battery, but then you have got the problem of transmitting the result in an isolated way.

I thought maybe since the chips linked have a differential mode that would get around the isolation problem. Oh, well.

23

dougp:
I thought maybe since the chips linked have a differential mode that would get around the isolation problem. Oh, well.

On an electric car you may have quite high overall voltages.
A differential mode is usually only valid "within the rails".

24

I can't help thinking there's got to be an electronic solution to this problem. Let me know if I'm being a nuisance

http://isolation-transmitter.com/download/JSD-TAF-1001S.pdf

Precision Optically Isolated Voltage Sensor

1-Wire voltage sensor TSV200-60i

25

dougp:
I can't help thinking there's got to be an electronic solution to this problem. Let me know if I'm being a nuisance

http://isolation-transmitter.com/download/JSD-TAF-1001S.pdf

Precision Optically Isolated Voltage Sensor

1-Wire voltage sensor TSV200-60i

  • First one provides pulse output only: hard to process with an arduino
  • Second one is fine, but SMD soldering skills and need to design a PCB
  • Last one is perfect, but expensive: at least 12* 75€