Tool/software:
Good morning, I have a 2S battery pack with the BQ40z50-R5 firmware that I have been trying to get do cell balancing in sleep and it never occurs. I have made sure of the following for the pack:
- Gauging is enabled - ManufacturingStatus[GAUGE_EN] = 1
- Balancing is enabled - GaugingStatus[BAL_EN] = 1
- There are no SafetyAlerts, SafetyStatus, or Permanent Failures
- A Field Learning Cycle has been performed - LSTATUS[FIELD_QMAX] = 1 and Gas Gauging -> State -> Update Status = 0xE
- Sleep is enabled - DA Configuration[SLEEP] = 1
- The cells are intentionally not balanced (one has an OCV of 4.238V and the other is at 4.222V)
- Cell Balancing in Sleep is Enabled - Balancing Configuration[CB] = 1 and Balancing Configuration[CBS] = 1
- The fuel gauge has taken at least two OCV readings and updated the cell balancing time - Cell 1 Bal Time = 0, Cell 2 Bal Time = 1998s
- The RSOC of the battery pack is at 90% which is above Start Rsoc for Bal in Sleep. I have set Start Time for Bal in Sleep artificially low in this screenshot to 1h to force it to happen more quickly just for testing (it is typically at 100h).
- The device will enter sleep after 5s of no I2C communication and the current is <10mA
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I believe that these are all the settings necessary to make sure cell balancing in sleep should happen. However, I have tried the following and cell balancing in sleep never happens (Cell 2 Bal Time remains at 199s8 and my inline current monitor I added to the battery cell never exceeds 1mA). I have tried:
- Physically disconnecting any I2C devices and power sources/sinks from the gauge to ensure that the device is going to sleep
- Adding a current monitor to both battery cells to ensure the device is going to sleep (current draw properly drops to sleep current levels and then jumps up a little bit every 5s to check the voltage like it should in SLEEP mode)
- Waiting over 100h to see if anything changes
- Forcefully putting the gauge in SLEEP mode by sending the MAC SLEEP command
I can confirm that cell balancing in charging works as I see the Cell 2 Bal Time decrease when that occurs. Also, if I enable Cell Balancing in Relax mode (Balancing Configuration[CBR]) I can see that working as well. Just nothing works to get cell balancing to happen in SLEEP. Any tips to get this working would be appreciated!
Thanks,
Mackenzie