Saturday, September 19, 2009

Regenerative braking works!

I had a brilliant tour of the Modec electric delivery-vehicle factory in Coventry, and they let me take a one-hour test-drive in an instrumented vehicle (pictured above).
The vehicle had perfectly good acceleration and its response to the pedals has been engineered to make it feel just like a 'normal' vehicle.
For me the most exciting details from the data from this 3.5-ton vehicle were: 1) three headline numbers - maximum power 80 kW; maximum regenerative power 20 kW; typical power at top speed 40 kW; 2) one nicely measured deceleration event from top speed to zero, which allowed an estimate of how efficient the regeneration is at capturing kinetic energy (the answer was that it was better than 50%; and the Modec engineers mentioned a redesign of the transmission that might further improve this efficiency). 3) overall regeneration figures, showing that the regenerative braking recovered roughly 15% of the energy used during the whole test-drive. The graph above shows by the green area the energy recovered, and by the red area the energy that went out from the battery.
Thank you, Modec!
Full story with factory tour images and data