Applicable Systems
BYD Battery Management System
Symptoms
The BYD BMS reports alarm BY001, indicating battery pack voltage abnormality. The pack voltage has deviated beyond the safe operating window, triggering protective shutdown of the battery system.
Possible Causes
- One or more cell modules have an internal short circuit, causing the cell voltage to collapse
- Battery Management System voltage measurement circuit has a faulty ADC or a blown fuse in the measurement harness
- Contactor or busbar connection has high resistance, causing voltage drop under load that exceeds the threshold
Troubleshooting Steps
- Step 1: Check the individual cell module voltages on the BMS monitoring interface
All cell voltages are within the normal range, typically 2.8V to 4.2V per cell depending on chemistry - Step 2: Verify the BMS voltage measurement circuit and harness fuse continuity
All measurement harness fuses are intact and the ADC readings match a calibrated reference voltage - Step 3: Inspect the contactor and busbar connections for corrosion or looseness with a thermal camera under load
No hot spots are detected at the contactor or busbar joints, confirming low resistance connections
How to Reset
To reset: 1) Replace any shorted cell modules. 2) Repair the BMS measurement circuit or harness. 3) Clean and tighten busbar connections. 4) Restart the BMS and verify pack voltage is within range.
Comments (0)
Share your experience to help others facing the same problem.
Leave a Comment
Source: BYD Battery Management System Manual, BYD Company Limited
Category: Battery
Published: 2026-09-30
No comments yet. Be the first to share your experience!