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1 Common BMS Problems and Solutions for Balcony battery storage, Residential, Commercial and Industrial Energy Storage
1.4 1.BMS cannot communicate with the host computer

Common BMS Problems and Solutions for Balcony battery storage, Residential, Commercial and Industrial Energy Storage

BMS stands for Battery Management System. It is a device that monitors the state of energy storage batteries. Its main functions are to intelligently manage and maintain individual battery cells, prevent overcharging and overdischarging of batteries, extend battery life, and monitor battery health. A BMS typically takes the form of a circuit board or a hardware box.
BMS failures are common in energy storage systems. Most BMS failures are not directly visible and often require specific methods and testing equipment to detect.
We noticed that the BMS isn't communicating with the host computer. Let's troubleshoot together to get things working smoothly!
BMS

1.BMS cannot communicate with the host computer

Possible reasons:
  1. CAN bus connection error. The BMS host computer can only communicate with the BMS through the internal CAN bus.
  2. Not connected to the CAN bus termination resistors. CAN bus communication requires termination resistors at both CANH and CANL (The 120Ω terminal resistor is typically attached to the all-in-one machine. The slave control board has a 120Ω terminal resistorbuilt into the wiring harness).
  3. CAN bus CANH and CANL are reversed.
  4. Internal CAN is occupied by other tools.
  5. Other
BMS SYSTEM
Check and solution:
  1. Check whether the host computer is connected to the BMS via internal CAN. If not, please connect via internal CAN.
  2. Measure the resistance value between the internal CAN bus CANH and CANL using a multimeter with the BMS powered off. If the resistance value cannot be detected, connect a 120Ω resistor between the CAN line CANH and CANL.
  3. Check whether CANH and CANL are connected inversely. If so, correct the connection.
  4. Check whether the computer/tablet is running other programs that occupy the CAN bus (PCAN-Explorer5, program refresh for the host computer, etc.). If occupied by other programs, turn them off and restart the host computer.
If none of these solutions work, don't worry! Let's document the issue in detail and share it with the relevant engineers. They'll be happy to assist further.
Below is the full version of common BMS problems and their solutions encountered during work.

2.Large Deviation Between Measured and Actual Cell Voltages

Possible Reasons:
1.Faulty connection of the cell voltage sampling connector;
2.Short circuit or open circuit in the cell sampling circuit;
3.Others.
Checks and solutions:
1.Disconnect the BMS power, remove and reconnect the cell voltage sampling connector;
2.Verify if the sum of measured cell voltages matches the actual sum, and if only consecutive cells exhibit significant voltage deviation while others are within normal range, this indicates a short circuit or open circuit in the cell sampling circuit. Contact the relevant engineer for inspection and repair;
3.If the problem persists, document the issue in detail and report it to the relevant engineer.

3.Possible reasons for the large difference between the total voltage sampling value and the actual individual voltage:

  1. The total voltage is not calibrated.
  2. other
Checks and solutions:
  1. Use the BMS host computer to re-calibrate the BMS.
  2. If the above solution does not resolve the issue, please record the problem in detail and provide feedback to the relevant engineer.

4.System total voltage sampling value fluctuates by more than 0.5V when there is no current or the current is small

Possible reasons:
  1. The resistance value of the voltage divider resistor at the total voltage sampling point is not suitable.
  2. Other (please specify)
Checks and solutions:
  1. Contact the relevant hardware engineer to determine the resistance value of the voltage divider resistor and replace the resistor.
  2. If the above methods do not solve the problem, please record the problem in detail and provide feedback to the relevant engineer.

5.One or more slave board information is missing, or the information of a certain slave board jumps frequently when using the BMS host computer to detect a system with multiple slave boards.

Possible reasons:
  1. The slave board numbers of multiple slave boards are duplicated.
  2. Other
Checks and solutions:
  1. Disconnect the system low-voltage connection, and check each slave board separately. If the slave board number of a certain slave board does not match the actual board number, please re-calibrate it.
  2. If the above methods do not solve the problem, please record the problem in detail and provide feedback to the relevant engineer.

6.The BMS data received by the host computer is intermittent.

Possible reasons:
  1. The BMS power supply comes in two voltage options: 12V and 24V. If the power supply is incorrectly calibrated, the BMS will not function properly.
  2. Other
Checks and solutions:
  1. Check if the power supply mode in the BMS calibrationdata is correct. If incorrect, please re-calibrate it.
  2. If the above methods do not resolve the problem, please record the problem in detail and provide feedback to the relevant engineer.

7.BMS detects that the temperature of a certain temperature sampling point in the battery pack is high, while the temperatures of other temperature sampling points are similar.

Possible reasons:
  1. Poor contact of the wiring at the temperature sampling point.
  2. Other
Checks and solutions:
  1. Open the battery pack for inspection and refasten the wiring harness at the temperature sampling point.
  2. If the above methods do not solve the problem, please record the problem in detail and provide feedback to the relevant engineer.

8.BMS total voltage and current fluctuate greatly during battery system charge and discharge test. The total voltage and current curves follow a similar pattern, while BMS total voltage and current sampling are normal under static conditions.

Possible reasons:
  1. The output current of the charge and discharge equipment fluctuates greatly, which leads to a large fluctuation of the total voltage at both ends of the battery, and therefore the sampling of the BMS total voltage and current fluctuates greatly.
  2. Others
Checks and solutions:
  1. Use an oscilloscope to capture the output current waveform of the charge and discharge equipment. If the current fluctuates greatly, it indicates that the BMS total voltage and current samplingare normal.
  2. If the above methods do not solve the problem, please record the problem in detail and provide feedback to the relevant engineers.

9.When calibrating BMS parameters, the host computer shows that the calibration is successful, but after the BMS is repowered, it is found that the calibrated parameter values are abnormal.

Possible reason:
After the host computer sends the calibration command, the BMS returns the calibration success to the host computer immediately after receiving the calibration command without completing the parameter calibration.
Checks and solutions:
After the calibration is completed, repower the BMS and check whether the BMS parameters are correct. If not, please re-calibrate.
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