Idle power consumption is the electricity a device uses while it is powered on but not actively delivering its primary function. In EV charging, idle power consumption refers to the energy an EV charger (EVSE) draws when it is not charging a vehicle—covering standby electronics, communications, displays, relays/contactors, heaters, and internal power supplies.
What Is Idle Power Consumption in EV Chargers?
An EV charger typically consumes some power even when no vehicle is connected or no session is active, for example:
– Control electronics and CPU/communications modem (Ethernet/4G/Wi-Fi)
– User interface (LEDs, display, card reader)
– Sensors and monitoring circuits (temperature, ground fault detection)
– Auxiliary power supplies and conversion losses
– Internal climate control (fans or heaters), especially in outdoor enclosures
This is sometimes called standby power.
Why Idle Power Consumption Matters
Idle power adds up across fleets and networks:
– In a multi-charger site, standby draw can become a measurable portion of annual electricity use
– It affects operating costs for hosts and CPOs, especially at low-utilization sites
– It impacts sustainability metrics and carbon reporting (Scope 2 electricity consumption)
– It influences site design decisions (always-on vs scheduled power, auxiliary heating needs)
For large deployments, reducing idle power improves both OPEX and environmental footprint.
Typical Factors That Increase Idle Power
Idle power consumption varies by charger design and site conditions:
– Always-on displays and high-brightness lighting
– Cellular connectivity and frequent communication polling
– RFID/payment terminals and contactless readers
– Enclosure heaters for cold climates (can dominate standby use)
– Active cooling fans running due to poor ventilation or hot weather
– Older or less efficient auxiliary power supplies
Outdoor public chargers usually have higher idle power than simple indoor AC wallboxes due to additional features and environmental protection needs.
How Idle Power Is Measured
Idle power can be assessed through:
– Metering at the circuit or charger supply while no session is active
– Charger diagnostics and telemetry via the CPMS (if supported)
– Aggregated energy accounting: comparing total site energy vs delivered kWh
For accurate reporting, measurement should specify the idle state clearly (no vehicle connected vs vehicle connected but not charging).
Reducing Idle Power Consumption
Common design and operational strategies include:
– Efficient auxiliary power supplies and low-power standby modes
– Display dimming, sleep modes, and event-based wake-up
– Optimized communication intervals while maintaining uptime monitoring
– Smarter thermal management (better insulation, controlled heater duty cycles)
– Scheduling non-critical components when the site is closed (where allowed)
– Firmware improvements to reduce unnecessary background activity (OTA firmware updates)
Reducing idle power must not compromise safety functions like fault monitoring or remote connectivity requirements.
Idle Power vs “Phantom Charging”
Idle power consumption is different from session energy:
– Idle power is energy used by the charger itself
– Charging energy is energy delivered to the vehicle (kWh billed)
– Some sites track both to understand “site overhead” and true energy cost per delivered kWh
This distinction matters for profitability analysis and sustainability reporting.
Related Glossary Terms
Standby Power
Auxiliary Power Supply
CPMS
Uptime
OCPP
Energy Monitoring
Scope 2 Emissions
Carbon Reporting
Load Balancing
OTA Firmware Updates