Eco-driving strategies in battery electric vehicle use – what do drivers get to know over time?

Eco-driving strategies in battery electric vehicle use – what do drivers get to know over time? Isabel Neumann, Thomas Franke, Franziska Bühler, Peter Cocron, and Josef F.Krems • 06.06.2014

EV user research at TU Chemnitz EV research topics dealing with… … low noise emission … regenerative braking function … acceptance of EVs … charging concepts (W2V) … multimodal electric mobility … adaptive drive train systems for EVs … user battery interaction … safety … user experience of limited range … eco-driving

Whatiseco-driving? • Sivak & Schoettle (2012): “eco-drivingincludesthosestrategicdecisions(e.g., vehicleselectionandmaintenance), tacticaldecisions(e.g., route selection), andoperational decisions(e.g., driverbehavior) thatimprovevehiclefueleconomy” (p.96) • morenarrow sense: • All strategies a dirvercouldapplytoreduceenergyconsumptionwhiledrivingandwhenplanning a trip Source: usgreenchamber.com Source: driverimprovement.co.nz

…andwhyiseco-driving different in BEV use? (gentle) Handling of thebattery Limited range Electricdrive Long charging durations; Limited charging opportunities Conceptofelectricity, consumptionin kWh Regenerative brakingsystem (activeenergyretrieval)

Previousresarch & researchobjectives • Eco-driving with conventional vehicles has been studied in depth (e.g., Wahlberg, 2007) • Besides some research on predominantly technical issues and small samples, not much is known about eco-driving when driving a BEV (e.g., Bingham, Walsh & Carroll, 2011) •  Current research objectives: • Which strategies do drivers know to drive energy efficiently with BEVs before and after 3 months of experiencing a BEV under daily driving conditions? • Do these strategies differ from strategies known with a conventional car? • Is there a need for additional information regarding energy consumption and retrieval in the BEV?

Method: MINI E international fieldtrial • MINI E Berlin as lead-study for large-scale international field trial Great Britain 40 vehicles USA 450 vehicles on the eastand west coast (CA, NY, NJ) Germany 65 vehicles in Berlin und Munich

Method: MINI E fieldtrial • Second periodof 6 monthswith 40 users in private setting: • Screening • Online • N =728 (applicants) • Screening via selection criteria • N = 40 users • Before receiving the car (3h) • Questionnaire (129 Items) • Face-to-face interview • Trip decision game • Conjoint anyalysis • Interview after first test drive with EV • After 3 months (2h) • Questionnaire (306 Items) • Face-to-face interview • Trip decision game • Conjoint analysis • Returning the car (2h) • Questionnaire (355 Items) • Face-to-face interview • Trip decision game • Conjoint analysis • 2nd Travel diary • 1 week, all trips • 3rd Travel diary • 1 week, all trips • 1st Travel diary • 1 week, all trips • 2nd Charging diary • 1 week • 1st Charging diary • 1 week May/June 2010 February/April 2010 . August 2010 2 test drives with EV

Sample • N = 40; 35 men, 5 women • Age: about 50 years (SD = 10.19) • Previous experience with electric drive: • 60% no previous experience at all • 40 % previous experience with HEV or BEV (short test drive) Annual milage: 80% between 10.000 to 30.000 km/year

Test vehicle • MINI E battery electric vehicle • Range: about 170 km under normal driving conditions • Regenerative braking implemented at the gas pedal • Displays: SOC, remaining range, instantanous & average consumption

Results: Eco-drivingstrategiesforconvenztionalvehicles Interview (T0): ‘Which strategies do you know to drive energy efficiently with your conventional car?’ N = 40

Results: Eco-drivingstrategiesfor BEVs vs. conventionalvehicles Interviews (T0 & T1): ‘Which strategies do you know to drive energy efficiently with the BEV?’ ** ** ** Sumof reportedstrategies: MdnT0 = 3 MdnT1 = 4* MdnICE= 4* N = 40

Results: userrequirementsregarding additional eneryconsumptionfeedback T1: ‘Please rate the benefit of the following possible additional systems.’ T1: ‘I would like to have some additional information regarding the energy consumption displayed in the BEV.’

Conclusions • Knowldege • Users report significantly more eco-driving strategies after 3 months of BEV driving than after a short test drive • Users report different strategies for conventional vehicles and BEVs • The most often mentioned eco-driving strategies with BEVs are: • Moderate acceleration* • Avoidance of auxiliary features* • Usage of regenerative braking *also found to be influencing factors in driving tests (Bingham et al., 2011) • Users seem to learn which factors influence the energy consumption of a BEV by experience Requirements regarding additional feedback • Users express need for additional information & regard the given systems as helpful (might be more relevant for other user groups)

Thanks a lot for your attention! Contact: isabel.neumann@psychologie.tu-chemnitz.de This study was funded by the German Federal Ministry for the Environment, Nature Conservation and Nuclear Safety. Source: Modiapple.com

Wissen: Eco-Driving Strategien mit dem EV Interviews (T0 & T1): Welche Strategien kennen Sie, um energieeffizient mit dem MINI E zu fahren? * * Summe berichteter Strategien: MdnT0 = 3 MdnT1 = 4 Z = -2.252; p = .024; r = -.25 N = 40

Methode: Testfahrt nach 3 Monaten EV Erfahrung • 2 Fahrten im Stadtverkehr; ca. 4 km Länge • 2 Fahrten mit 2 Instruktionen: (1) Normaler Fahrstil (Kalibrierungsfahrt) (2) Eco-driving • Datenlogger (BMW): Geschwindigkeit (SD, Mean), Beschleunigung (SD, Mean), Motorleistung (inkl. Rekuperation), Rekuperationsleistung, Strecke, Zeit, Außen- & Batterietemperatur… • Protokoll zur Testfahrt, Fragebogen & Interview

MINI E Berlin – powered by Vattenfall 24.09.2009 Isabel Neumann

Eco-driving strategies in battery electric vehicle use – what do drivers get to know over time?