48V Lithium-Ion Battery Cell Voltage Imbalance
2019-2024 BMW 3 Series G20 2.0L I4 Turbo B48
Description
One or more cells in the 48V lithium-ion battery have voltage that deviates significantly from other cells in the pack.
Symptoms
- 48V system limited
- Mild hybrid features intermittent
- 48V battery not holding charge
- Warning indicator for 48V system
- Reduced energy recovery
Common Causes
- Individual cell degradation
- Cell manufacturing variation
- Temperature gradient across pack
- BMS balancing circuit failure
- Extended storage without maintenance charge
Diagnostic Steps
- Read individual 48V cell voltages
- Check cell voltage spread
- Monitor balancing activity
- Test 48V battery temperature uniformity
- Review battery age and usage history
Repair Notes
Replace 48V battery pack if cell imbalance exceeds threshold. 48V batteries are typically replaced as a complete unit.
Related Codes
Other Powertrain Codes
- P0001Fuel Volume Regulator Control Circuit/Open
- P0002Fuel Volume Regulator Control Circuit Range/Performance
- P0003Fuel Volume Regulator Control Circuit Low
- P0004Fuel Volume Regulator Control Circuit High
- P0010Intake Camshaft Position Actuator Circuit/Open Bank 1
- P0011Intake Camshaft Position Timing Over-Advanced Bank 1
- P0012Intake Camshaft Position Timing Over-Retarded Bank 1
- P0013Exhaust Camshaft Position Actuator Circuit/Open Bank 1
- P0014Exhaust Camshaft Position Timing Over-Advanced Bank 1
- P0015Exhaust Camshaft Position Timing Over-Retarded Bank 1
P3808 on Other Vehicles
Common Questions
What does code P3808 mean on a 2019-2024 BMW 3 Series G20?
P3808 stands for "48V Lithium-Ion Battery Cell Voltage Imbalance". One or more cells in the 48V lithium-ion battery have voltage that deviates significantly from other cells in the pack.
What are the symptoms of P3808 on a BMW 3 Series G20?
Common symptoms of P3808 include: 48V system limited, Mild hybrid features intermittent, 48V battery not holding charge, Warning indicator for 48V system, Reduced energy recovery.
What causes P3808 on a 2019-2024 BMW 3 Series G20?
Common causes of P3808 include: Individual cell degradation, Cell manufacturing variation, Temperature gradient across pack, BMS balancing circuit failure, Extended storage without maintenance charge.