eco-driving strategies in battery electric vehicle use – what do drivers get to know over time?...
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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.Krems06.06.2014
Isabel NeumannEuropean conference on Human Centred Design for
Intelligent Transport Systems
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
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What is eco-driving?
- Sivak & Schoettle (2012):
“eco-driving includes those strategic decisions (e.g., vehicle selection and maintenance), tactical decisions (e.g., route selection), and operational decisions (e.g., driver behavior) that improve vehicle fuel economy” (p.96)
- more narrow sense:
All strategies a dirver could apply to reduce energy consumption while driving and when planning a trip
Source: usgreenchamber.com
Source: driverimprovement.co.nz
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…and why is eco-driving different in BEV use?
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(gentle) Handling of the battery
Limited range
Regenerative braking system (active energy retrieval)
Long charging durations;
Limited charging opportunities
Electric drive
Concept of electricity,consumption in kWh
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Previous resarch & research objectives
- 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:
(1) Which strategies do drivers know to drive energy efficiently with BEVs before and after 3 months of experiencing a BEV under daily driving conditions?
(2) Do these strategies differ from strategies known with a conventional car?
(3) Is there a need for additional information regarding energy consumption and retrieval in the BEV?
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Method: MINI E international field trial
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- MINI E Berlin as lead-study for large-scale international field trial
USA450 vehicles on the east
and west coast (CA, NY, NJ)
Germany65 vehicles in
Berlin und Munich
Great Britain40 vehicles
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Method: MINI E field trial
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Second period of 6 months with 40 users in private setting:
Screening- Online- N =728
(applicants)- Screening via
selection criteria- N = 40 users
1st Travel diary- 1 week, all trips
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
2nd Travel diary- 1 week, all trips
3rd Travel diary- 1 week, all trips
1st Charging diary- 1 week
2nd Charging diary- 1 week
Returning the car (2h)- Questionnaire (355
Items)- Face-to-face interview- Trip decision game- Conjoint analysis
May/June2010
February/April 2010
. August 2010
2 test drives with EV
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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
< 5.000 5.000 - 1.0000
10.000 - 15.000
15.000 - 20.000
20.000 - 30.000
30.000 - 40.000
40.000 - 50.000
0
5
10
15
20
25
30
35
Annual milage (km/year)
Pro
po
rtio
n (
%)
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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
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Results: Eco-driving strategies for convenztional vehicles
N = 40
Avoid braking/let the car roll
Drive evenly (speed & acceleration)
Optimal tires/tire pressure
Minimize load
Avoid idling
Avoid high speeds
Avoid auxiliary functions (e.g., AC)
Anticipatory driving style
Accelerate moderately
Use highest gear possible
0 10 20 30 40 50 60 70 80 90 100Proportion of drivers reporting the strategy (%)
Interview (T0): ‘Which strategies do you know to drive energy efficiently with your conventional car?’
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Results: Eco-driving strategies for BEVs vs. conventional vehicles
Optimal tires/tire pressure
Chooseenergy efficient route
Minimize load
Let the car roll (sailing)
Instantaneous power meter
Drive evenly (speed & acceleration)
Avoid high speeds
Anticipatory driving style
Use regenerative braking /avoid braking
Accelerate moderately
Avoid auxiliary functions (e.g., AC)
0 10 20 30 40 50 60 70 80 90 100
ICE
after short test drive
after 3 months EV usage
Proportion of drivers reporting the strategy (%)N = 40
Sum of reported strategies:
MdnT0 = 3
MdnT1 = 4*
MdnICE= 4*
**** **
Interviews (T0 & T1): ‘Which strategies do you know to drive energy efficiently with the BEV?’
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Results: user requirements regarding additional enery consumption feedback
1
2
3
4
5
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Additional information / assistance
As
se
ss
me
nt;
95
% C
I
T1: ‘I would like to have some additional information regarding the energy consumption displayed in the BEV.’
1
2
3
4
5
6
Ag
ree
me
nt;
95
% C
I
T1: ‘Please rate the benefit of the following possible additional systems.’
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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)
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Thanks a lot for your attention! Contact: [email protected]
This study was funded by the German Federal Ministry for the Environment, Nature Conservation and Nuclear Safety.
Source: Modiapple.com
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Wissen: Eco-Driving Strategien mit dem EV
N = 40
**
Optimal tires/tire pressure
Energy efficient route to destination
Minimize load
Let the car roll (sailing)
Instantaneous power meter
Drive evenly (speed & acceleration)
Avoid high speeds
Anticipatory driving style
Use regenerative braking /avoid braking
Accelerate moderately
Avoid auxiliary functions (e.g., AC)
0 10 20 30 40 50 60 70 80 90 100
after short test drive
after 3 months EV usage
Proportion of drivers reporting the strategy (%)
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
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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
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24.09.2009Isabel Neumann