BMS Error Detection¶
The Firmware detects electrical failures based on thresholds in software.
Overcurrent / Overload / SCP¶
| Display Pattern for Pack with Error | Other Packs of the Set |
|---|---|
| ⚫🔴🔴⚫⚫ | ⚫🔴⚫🔴⚫ |
Measurement (SCP protection method):
An analog comparator of the STM32 uses the measurement of the battery current (by current sense amplifier, 10 mV/A, 500 mV offset) and a reference voltage (generated by the STM32). When the comparator indicates, that the current is higher than a threshold, the output triggers and the BMS output latches are turned off immediately (analog circuit). Additionally, an interrupt triggers and stores the short circuit event in software for further processing.
SCP Current Threshold (Device Tree configured): -120 A for BMS@D.2, -80 A for BMS@D.1
Measurement (Overcurrent):
The analog thread samples the battery current. As soon as the current exceeds the threshold, the error gets detected (relevant during charging process).
Overcurrent Threshold: 24 A
Overtemperature¶
| Display Pattern for Pack with Error | Other Packs of the Set |
|---|---|
| ⚫⚫🔴🔴⚫ | ⚫🔴⚫🔴⚫ |
Measurement:
The analog thread samples the temperature values. As soon as two temperature measurements on the BMS exceed a configured threshold, the overtemperature gets detected.
Threshold: 60 °C
Notes: Cell should be able to operate at 80°C (but not in datasheet...)
Overvoltage¶
| Display Pattern for Pack with Error | Other Packs of the Set |
|---|---|
| 🔴🔴🔴🔴⚫ | ⚫🔴⚫🔴⚫ |
Measurement:
The analog thread samples the voltage values of the battery and its cells. If the measured battery voltage or cell voltage value exceed the corresponding threshold, the overvoltage gets detected.
Threshold: Battery 25.5 V, Cells 4.25 V
Undervoltage¶
| Display Pattern for Pack with Error | Other Packs of the Set |
|---|---|
| 🔴⚫⚫⚫⚫ | ⚫🔴⚫🔴⚫ |
Measurement:
The analog thread samples the voltage values of the battery and its cells. If the pack is discharging (the discharge current is lower than threshold) and the measured batter or cell voltage value is below the corresponding threshold, the undervoltage gets detected.
Discharge current threshold: -600 mA Threshold: Battery 16.2 V, Cells 2.5 V
Vpack always on¶
| Display Pattern for Pack with Error | Other Packs of the Set |
|---|---|
| ⚫🔴⚫🔴⚫ | ⚫🔴⚫🔴⚫ |
Measurement:
If the latches are disengaged and the BMS is not connected (slot pin indicates an open wire, and the connection pin is open), a voltage above threshold on pack side is detected as error. Reason could be a bricked latch and the pack can no longer be turned off.
Threshold: 10 V
Set Unbalanced Error¶
| Display Pattern for Pack with Error | Other Packs of the Set |
|---|---|
| ⚫🔴⚫🔴⚫ | ⚫🔴⚫🔴⚫ |
Measurement:
The battery voltages of all BMS pack of the set are received and evaluated. The set maximum and minimum battery voltage is calculated and the difference is compared to a threshold.
Threshold: 500 mV
Set Error¶
| Display Pattern for Pack with Error | Other Packs of the Set |
|---|---|
| ⚫🔴⚫🔴⚫ | ⚫🔴⚫🔴⚫ |
Measurement:
The states of all BMS pack of the set are received and evaluated. If any other pack is in the Error state, this is detected as error.
Cyphal Set Receive Error¶
| Display Pattern for Pack with Error | Other Packs of the Set |
|---|---|
| ⚫🔴⚫🔴⚫ | ⚫🔴⚫🔴⚫ |
Measurement:
If another set is connected to the same CAN bus, it gets monitored as well. If too many other sets are present, this error indicates an overflow of monitored other BMS sets.
Threshold: 10 other sets