The battery weight in plug-in hybrid electric vehicles (PHEVs) significantly affects their fuel efficiency on long trips in a nuanced way:
- Larger batteries enable PHEVs to travel farther on electric power alone before switching to using liquid fuel. This extended electric range reduces fuel consumption initially, thereby improving fuel efficiency on shorter trips or at the start of long trips when the battery is charged.
- However, batteries have much lower energy density compared to gasoline, meaning they weigh considerably more per kWh of stored energy. A typical PHEV battery pack can weigh between 100 to 600 kg, plus additional structural weight the vehicle must carry even after the battery is depleted, whereas 10 gallons of gasoline weighs only about 28 kg.
- This extra weight reduces overall vehicle efficiency. The heavier battery load increases energy consumption both in electric mode (electric miles per kWh decrease) and in hybrid mode after the battery is depleted (miles per gallon decrease). Essentially, the vehicle uses more energy to carry the heavier battery, negating some benefits of the larger electric range during long trips where fuel combustion is dominant.
- For long trips that exceed the all-electric range (AER), the fuel efficiency penalty from the added battery weight becomes more apparent because the vehicle relies more on the internal combustion engine, which must also move the heavier battery pack.
- On shorter trips within the electric range, bigger batteries save more fuel despite the weight penalty. Beyond that range, the weight penalty can cause slightly worse fuel economy compared to smaller battery PHEVs.
In summary, while larger batteries in PHEVs improve electric-only range and reduce fuel usage at the start of a trip, their heavier weight decreases efficiency during extended driving on fuel alone. This trade-off means that on long trips beyond the battery’s electric range, heavier batteries can lead to reduced fuel efficiency due to the increased energy needed to move the added mass.
Original article by NenPower, If reposted, please credit the source: https://nenpower.com/blog/how-does-the-battery-weight-in-phevs-affect-their-fuel-efficiency-on-long-trips/
