BYD BYD Battery Management System Error Code BY014

BYD Battery Major Communication

Model: BYD Battery Management System | Code: BY014

Applicable Systems
BYD Battery Management System

Symptoms

The BMS communication link to the inverter or SCADA system has failed. The inverter cannot read battery state of charge and defaults to a conservative power limit.

Possible Causes

  • CAN bus cable damaged or connector loose between BMS and inverter
  • BMS communication port failure due to electrical surge
  • Inverter communication firmware incompatible with the BMS protocol version
  • CAN bus termination resistor missing or incorrect value

Troubleshooting Steps

  1. Step 1: Check the CAN bus cable continuity and connector seating
    Replace damaged cables; ensure connectors click into place
  2. Step 2: Verify the CAN bus termination resistors (120 ohm) at both ends
    Measure 60 ohm across the bus with both terminators installed and power off
  3. Step 3: Check the BMS and inverter communication settings for matching baud rate and protocol
    Update firmware on both devices to compatible versions
  4. Step 4: If the BMS communication port is damaged, the BMS board needs replacement
    Use an oscilloscope to verify CAN bus signal quality

How to Reset

Reset: Communication restores automatically once the link is re-established and both devices confirm protocol compatibility.

Common Replacement Parts

  • CAN bus cable: Twisted pair, 120 ohm characteristic impedance (Use shielded cable in industrial environments)
  • Termination resistor: 120 ohm, 1/4W, metal film (Install at both physical ends of the bus)
  • BMS communication board: CAN bus or RS485 interface (Match to inverter protocol)

Frequently Asked Questions

  • Q: What is CAN bus termination?

    Resistors at both ends of the CAN bus absorb signal reflections. Without them, signal reflections cause communication errors. Value: 120 ohm to match cable impedance.

  • Q: How do I check CAN bus with an oscilloscope?

    Connect across CAN-H and CAN-L. A healthy bus shows clean differential pulses with 1.5-2V peak differential voltage. Distorted or low-amplitude signals indicate a problem.

  • Q: Can I use RS485 instead of CAN?

    Yes, many BMS systems support both. RS485 is simpler but has slower data rates. CAN is preferred for real-time battery monitoring.

Related BYD Fault Codes

Source: OEM Technical Manual

Category: Battery