BYD | State of Charge (SOC) & Charge Control

Initial SOC during commissioning
New HVS/HVM modules are delivered with a state of charge of approximately 30%. When a new battery system is commissioned, the BCU often initially displays an incorrect SOC, commonly 50%, 30% or 0%. This should be understood as a placeholder value because the BCU does not yet know the actual state of charge of the modules. As soon as the battery begins charging, SOC detection is corrected step by step. The SOC calibration is completed at the latest after a full cycle: charging to 100% followed by discharging to the permitted maximum depth of discharge.

SOC jumps
The state of charge of an LFP battery is not measured directly; it is calculated. Battery voltage is an important factor, but temperature, current flow and charging behaviour also influence the calculation. SOC estimation is generally more accurate when the battery regularly completes full cycles. The displayed SOC is therefore an approximation and can differ by several percentage points from the actual value. Occasional corrections or jumps in the displayed SOC are normal.