Would plug-in hybrid buyers be interested in having a choice of battery pack sizes? The authors of a new study seem to think so, recommending that manufacturers should develop a modular design for PHEVs and EREVs, allowing them to offer a choice of storage capacity to meet individual customer requirements.

The study, written by a team from the Institute of Vehicle Concepts, German Aerospace Center (DLR) and published in the journal Energy Policy, focuses specifically on the German market. It suggests that OEMs offer (for example) three different battery sizes for drivers with low, average and high mileage.

The DLR team analyzed the effect of different driving profiles, and found that battery size has a significant effect on total cost of ownership. For a German EREV owner who drives 15,000 km per year, a battery capacity of 6 kWh would be cost-optimal by 2020. However, the optimal size changes to 2 kWh if the annual mileage is halved, and to 13 kWh if annual mileage is doubled.

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“Two of the most promising powertrain technologies are plug-in hybrid (PHEV) and extended range (EREV),” writes lead author Martin Redelbach. “However, the battery is still a very critical component due to the high production cost and heavy weight. Therefore, the right sizing of the battery is the key for electric powertrains to meet customer expectations and become cost-competitive against conventional technologies.”

Of course, as automakers are well aware, the logical conclusions of academics do not always line up with car buyers’ behavior. “This paper assumes a rational customer who has objective to minimize the total cost of ownership,” writes Redelbach. “In reality, the behavior of consumers may not be fully rational. Consumers may prefer high electric range due to several reasons.”

Source: Energy Policy via Green Car Congress