Voltage of single cell jumps alot

[BjoernRave]

The voltage of my 1. cell is different with every request. These requests were made directly after each other:

{
  "1": 4.258,
  "2": 3.367,
  "3": 3.369,
  "4": 3.366
}
pi@raspberrypi-main:~ $ daly-bms-cli -d /dev/ttyUSB0 --cell-voltage
{
  "1": 3.868,
  "2": 3.367,
  "3": 3.368,
  "4": 3.366
}
pi@raspberrypi-main:~ $ daly-bms-cli -d /dev/ttyUSB0 --cell-voltage
{
  "1": 4.444,
  "2": 3.367,
  "3": 3.369,
  "4": 3.37
}
pi@raspberrypi-main:~ $ daly-bms-cli -d /dev/ttyUSB0 --cell-voltage
{
  "1": 4.307,
  "2": 3.366,
  "3": 3.368,
  "4": 3.363
}
pi@raspberrypi-main:~ $ daly-bms-cli -d /dev/ttyUSB0 --cell-voltage
{
  "1": 4.383,
  "2": 3.366,
  "3": 3.369,
  "4": 3.365
}
pi@raspberrypi-main:~ $ daly-bms-cli -d /dev/ttyUSB0 --cell-voltage
{
  "1": 4.463,
  "2": 3.366,
  "3": 3.369,
  "4": 3.365
}

The iOS app SmartBMS is telling me that the 1. cell is at around 3.6v.

[dreadnought]

Hi, I see this behavior when the battery gets discharged, not while being idle or charging. The same happens to the current in --soc, while the total_voltage is stable.

I don't know why it happens or what the mobile app does different. As far as I can see there is nothing wrong in the communication, the BMS sends the values like we see them. If you want it to look better in the visualization, you can calculate the moving average to make the chart look smoother.

[bergyla]

Hi Bjorn, I think a Lifepo4 voltage at about 4,x V are fairly faulty. I saw such behavior by bad contacts (high resistance) of the sense wiring. You might double check your hardware setup.