P3808high severityPowertrain
48V Lithium-Ion Battery Cell Voltage Imbalance
on 2021 Mazda Mazda3 2.5L I4 · FWD
What this code means
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.
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