Two battery systems can both report that balancing is taking place while using different circuits. Passive balancing removes a small amount of charge from selected cells through a resistive path. Active balancing transfers energy between parts of the battery using additional circuitry.
Balancing is a controlled operation
The controller decides when balancing is permitted. Its operating conditions, available current and monitoring strategy depend on the design. A scan showing no balancing activity at one moment is therefore not enough to condemn a circuit.
When discussing a battery report, ask which system is fitted and whether the recorded conditions allowed balancing. Keep the cell-voltage data, temperature, charge level and any relevant faults together. Comparing readings from unrelated operating conditions can give a misleading impression of progress.
Agree what the proposed work can achieve
Balancing adjusts charge distribution. It does not replace material lost through cell deterioration or repair an open sensing connection. A proposal should explain why an imbalance occurred and what evidence separates a control issue from a cell problem.
Do not assume an active-balancing device can be added to a production pack as a simple upgrade. Pack safety, monitoring and software were designed as a system. High-voltage packs require the correct competence, equipment and manufacturer procedures; this guide is an explanation of the hardware, not an instruction to open one.
Arrange an assessment
For EV and hybrid diagnostics, send the vehicle details and fault report to AXION. We support enquiries from drivers and garages. Workshop, postal and remote options depend on the job and are confirmed before booking.
Technical reference
Read the supporting technical documentation. The referenced design or vehicle application defines its scope; it is not a universal repair procedure.
Related reading
Battery open-wire detection and a misleading cell-voltage reading. Browse the automotive electronics repair library for other systems and symptoms.