In short
- JBD boards balance passively: they bleed a little current from the highest cells as heat.
- Balancing starts only above a start voltage and when cells differ by more than a set delta.
- With LiFePO4, the useful window is near the top of charge, so balancing happens in short bursts.
Most JBD smart BMS boards use passive balancing. When a cell is higher than the others, a small resistor across that cell burns off a little energy until the gap closes. The current is modest, so balancing is slow and works on small differences.
The two settings that decide
The start voltage sets the level above which balancing is allowed. The delta, or balance difference, sets how far apart cells must be before the BMS acts. If either condition is not met, nothing happens, even when the app shows a visible spread.
Only while charging
Many JBD boards offer an option to balance only during charge. It avoids burning energy at night when the pack is discharging, but it also shortens the time available to balance. Check whether yours is on.
Why LiFePO4 makes it look idle
Across most of its range, LiFePO4 voltage is almost flat. Cells that hold different amounts of energy show nearly the same voltage until they approach full. The BMS cannot see the difference earlier, so it balances in the last part of the charge, often for less than an hour a day.
Signs that balancing is not enough
A spread at the top of charge that grows week after week, one cell that always triggers the over-voltage protection, or a pack that never reaches full: these suggest a weaker cell, a loose connection, or a gap larger than passive balancing can handle.
Watching the right moment
JBD Monitor reads every cell and the balancing state from the BMS and keeps the history. The useful view is the cell spread at the end of each charge, day after day. A stable or shrinking spread means balancing keeps up.
Common questions
Should I lower the start voltage to balance more?
Not much below the knee of the LiFePO4 curve, around 3.40 V. Lower, the voltages hardly differ and the BMS may balance the wrong way.
Can JBD Monitor force balancing?
No. It only reads the BMS and never writes a setting.
What spread is acceptable?
At the top of charge, a few tens of millivolts is common. What matters most is whether it stays stable over time.
