Power lithium battery communication failure and voltage failure

　　1. Communication failure

　　LUM communication fails, BMU communication fails; the vehicle has one or more LMU information, or the vehicle has no BMS information.

　　The cause of the failure: LMU/BMU failure; (2) LMU/BMU power supply line or communication line has poor contact/fault; (3) signal interference.

　　Treatment: replace LMU/BMU; check and repair the power supply line/communication line; (3) check the picture and check the line to find and eliminate the source of interference.

　　Voltage failure

　　1. High battery voltage: After the battery is fully charged and allowed to stand still, the voltage of a single or multiple series of batteries will increase significantly, and other cells will be normal.

　　(1) Acquisition error; (2) LMU balance function is poor or invalid; (3) The battery capacity is low and the charging voltage rises quickly.

　　(1) The cell voltage display value is higher than other cells, measure the actual voltage value of the cell for comparison. If the actual value is lower than the displayed value and the voltage is the same as that of other cells, the LMU cell voltage is calibrated based on the actual value; if the measured value is consistent with the displayed value, manually perform the discharge balance of the cell. (2) Check whether the voltage sampling line is disconnected or not connected; replace LMU.

　　2. Low battery voltage: After the battery is fully charged with static electricity, the voltage of the battery cell or multiple cells is obviously low, and the other cells are normal.

　　(1) Acquisition error; (2) LMU balance function is poor or invalid; (3) Battery self-discharge rate; (4) Battery capacity is low, and discharge voltage drops quickly.

　　(1) The cell voltage display value is lower than other cells, measure the actual voltage value of the cell for comparison. If the actual value is higher than the displayed value and is the same as other monomers, the actual value is used to calibrate the LMU monomer voltage; if the measured value is consistent with the displayed value, manually charge the single battery. (2) Check whether the voltage sampling line is disconnected or not connected; (3) Replace the LMU; replace the problematic battery pack.

　　3. Pressure difference: dynamic pressure difference/static pressure difference. When charging, a single voltage quickly reaches the cut-off voltage to jump the gun; when the accelerator is stepped on, the cell voltage drops faster than other series; when the brake is applied, the single voltage rises faster than the other series.

　　(1) The cause of the failure: The fastening nut of the copper plate of the battery is loose; (2) There is dirt on the connection surface; (3) The battery self-discharge rate; (4) The open welding of the copper plate of the battery welding joint (resulting in the low monomer capacity of the string ); Single cell leakage.

　　Treatment method: tighten the nut; remove foreign objects on the connecting surface; balance the charge and discharge of a single battery; replace the battery pack with the problem.

　　4. Voltage jump: a single voltage jump occurs when the vehicle is running or charging.

　　(1) The connection point of the voltage acquisition line is loose; (2) The fault zone.

　　Solution: Tighten the connection point; (2) Replace LMU.