PHEV — Plug-In Hybrid Specifics

A plug-in hybrid electric vehicle (PHEV) is a hybrid with a bigger battery, a charge port, and the ability to drive significant distances on electricity alone. A standard hybrid like a Toyota Prius has a battery around 1 to 2 kilowatt-hours — enough for a mile or two of electric driving. A PHEV has a battery of 10 to 20 kilowatt-hours — enough for 25 to 50 miles of pure electric driving. Once the battery is depleted, the vehicle operates like a standard hybrid, using the engine and battery together.

PHEVs operate in two modes. Charge-depleting mode: the vehicle uses battery power primarily, and the engine starts only when the driver demands more power than the electric motor can provide. The battery state of charge drops from full toward a target minimum (usually 15 to 25 percent). Charge-sustaining mode: once the battery reaches that minimum, the vehicle switches to standard hybrid operation — the engine runs regularly and the battery state of charge is maintained in a narrow range, just like a non-plug-in hybrid. Most PHEVs also have an EV mode button to force electric-only driving and a Hybrid mode to blend both power sources.

PHEVs have an onboard charger that converts AC power from a wall outlet or charging station into DC power to charge the battery. Most PHEVs use a Level 1 (120V household outlet) or Level 2 (240V) charger. The onboard charger is typically rated at 3.3 kW to 7.2 kW. A full charge from empty takes 2 to 8 hours depending on the charger rating and battery size. Some newer PHEVs also support DC fast charging, but this is less common since the batteries are small enough to charge reasonably fast on Level 2.

Toyota makes the RAV4 Prime (42 miles EV range) and Prius Prime (44 miles EV range). Hyundai and Kia make the Tucson PHEV, Sorento PHEV, and Santa Fe PHEV. Ford makes the Escape PHEV. Chrysler makes the Pacifica PHEV — the only plug-in hybrid minivan. BMW offers PHEV versions of the 3 Series, 5 Series, X3, and X5. Volvo offers T8 PHEV across their lineup. Mercedes offers EQ Power PHEV models.

PHEV batteries are larger and higher voltage than standard hybrid batteries — typically 300 to 400 volts compared to 200 to 270 volts on a standard hybrid. The cooling system for the battery is more robust because the battery is discharged more deeply and more frequently. The charge port, onboard charger, and charge door actuator are additional components that do not exist on a standard hybrid. PHEVs require the same HV safety precautions as any hybrid — de-energize the HV system before working on any orange-cabled component. Always check the HV interlock before starting work.