🔋 Understanding Phantom Drain and Phantom Charge: Battery Behavior During Idle State

When a vehicle is parked or in standby mode, a decrease in the battery's state of charge (SOC), known as phantom drain, or an increase, known as phantom charge, is typically a normal phenomenon that occurs as the Battery Management System (BMS) recalibrates the battery status. Recently, the term phantom drain has also come to include not just changes in SOC, but the actual energy consumption during idle periods.

The following diagram explains the mechanism behind changes in battery level even when the vehicle is not consuming energy.When the vehicle is completely stopped and no current is flowing, the voltage—referred to as OCV (Open Circuit Voltage)—varies depending on the type of battery. In particular, NCM and LFP batteries show significant differences in their voltage curves.

The BMS uses these OCV characteristics to recalibrate the SOC while the vehicle is idle. As a result, users may observe that the battery level appears to have increased or decreased after charging or driving. Some manufacturers choose not to show these changes to users or display them gradually to reduce confusion.

Dr.EV has added a feature to monitor phantom drain and phantom charge in real time, based on user requests.

• When the measured value is negative, it indicates phantom drain

• When the measured value is positive, it indicates phantom charge

  
  

We will continue to develop interesting and useful features related to vehicles, and we actively welcome your suggestions.

Thank you.