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Ford Focus Electric gets a 95% braking regen efficiency

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frankydude · · 1 year ago

We had a bad press article from a "professionnal" auto chroniquer/reviewer done in august in a major Montreal newspaper. The chroniquer wanted to try to reach Old Orchard Beach from Montreal with a Ford Focus Electric (FFE). He reached the Vermont border, badly managed the recharge (with 120V) and returned back. His misplanned trip ended up on a flatbed.

To show how dumb this guy is, Sylvain Juteau (who own a FFE) did the trip from Trois-Rivieres, Quebec to Old Orchard Beach. He did the trip in two days, and on the going to destination, he also put himself on a "First": He was the first production BEV to climb Mount Washington.

On his up and down of the mountain, Sylvain took two pictures of his energy indicator on his dash: The first one is at the top of the mountain.
http://roulezelectrique.com/wp-content/uploads/2012/09/Mt-Washington-ene...
He started his climb by being fully charged from a plug near the welcome center of the Mt Washington Auto Road, and after he reached the summit, he had used 9.3kWh, and rolled a distance of 12.7km.
The altitude differential is of 1420 meters (4659 feet)
The weight of the Ford and it's occupants and luggages were of 1889kg / 4156 lbs
From there, he took the ride down to his starting point, where he took another picture of his energy summary: http://roulezelectrique.com/wp-content/uploads/2012/09/Energie-MtWashing...
The display show 24.8km rolled from the start, and 4.1kWh of energy net use.
so, on the going down, the car recovered 5.2kWh of energy through the regen braking. How efficient is that?
Well, the potential energy of the car at the summit is of :
1889kg x 9.8 m/s² x 1402m = 25954104 Joules If we convert this to kWh:
25954104 Joules / (1000 x 3600s/hr) we obtain: 7.2kWh
So the car recovered 5.2kWh / 7.2kWh x100 = 72%
BUT that number does not take into account rolling resistance to drive 12.4km on the auto road... The FFE does about 0.150kWh per km of energy usage on flat level road. If we take into account the energy normally used to drive 12.4km, we get: 12.4km x 0,150kWh/km = 1.86kWh
so the regen efficiency would be:
(Net Recovered energy + rolling losses)x100/Potential Energy = % regen efficiency.
(5.2kWh +1.86kWh) x 100 / 7.2kWh = 96%

This is a very very highly efficient number. The rolling losses is the experimental data that could have the greatest precision impact on this computation, but we can be certain that the regen efficiency is in the range of between 72% and 96%.

I am impressed.

Comments

· · 1 year ago

I am impressed with your "back of a napkin" energy calc's. Very good. Do you have any comments about the quality of the re-gen on the FFE from a drivers perspective? I ask because reading the reports of an owner of a BMW Active E, he mentioned that re-gen on that cars is pleasant.

· Gabriel (not verified) · 1 year ago

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· Gabriel (not verified) · 1 year ago

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· PHILLIP (not verified) · 1 year ago

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