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pinaz
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EPA fuel economy
pinaz   12/30/2013 2:40:24 PM
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My understanding is that the EPA fuel economy test downplays any benefit to stop-start, as there are no significant stops in the test.  As a result, there is no visible benefit to the consumer when comparing the "sticker" mileage of vehicles.

junko.yoshida
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Re: EPA fuel economy
junko.yoshida   12/30/2013 3:25:10 PM
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@pinaz, you are absolutely right.

Accoridng to Automoitve News (http://www.autonews.com/article/20131104/OEM06/311049962/daimler-asks-epa-to-let-tech-features-bolster-its-mileage-ratings#axzz2ozWlV866

Daimler is seeking to get better treatment under new U.S. fuel economy standards for its start-stop technology and other fuel-saving features.

geekmaster
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Hybrids use already stop-start?
geekmaster   12/30/2013 3:31:08 PM
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Hi Junko!

I thought that Hybrids use already stop-start. We drive a Toyota Prius C and the motor stops when the car stops. By the way: the battery charges when we hit the break! Very impressive.

junko.yoshida
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Re: Hybrids use already stop-start?
junko.yoshida   12/30/2013 4:44:29 PM
@Descartes, oui, bien sur, they do.  

In fact, as I wrote in the story (page 2), hybrid/electric assist vehicles experience almost no delay in power from a stop, due to the instant availability of power from the traction battery to the electric motors.

The issue is when we try to do this on our non-hybrids.

Non-hybrids must rely on a run-of-the-mill starter motor, which is usually too weak for a seamless reboot. That results in that slight partial-second delay in gasoline cars. One solution is to increase the size of the starter motor. But this would add weight and cost.

Alvie
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start stop is no news in EU
Alvie   12/30/2013 4:57:30 PM
Start&stop tech is no news in Europe at least, marketed with different names by all the vendors. I personally own a Volkswagen Tiugan, diesel, year 2011, which uses the same tech marketed as "bluemotion". All I can say is it works painlessly, engine shuts down exactly when I want, restarts quickly, saves quite some fuel when transit stops - but make sure you do not use it for short stops, might not save fuel at all, but the opposite. From my experience, a 2-3 minute or more stop is worth using S&S, less than this does not.

junko.yoshida
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Re: start stop is no news in EU
junko.yoshida   12/30/2013 5:16:41 PM
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@Alvie, thanks for chiming in. I know many cars sold in Europe and in Japan come with stop-start technology already. Your observation as to when th feature becomes most effective is fascinating!

philmck
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Delay may be less than a stick shift
philmck   12/30/2013 6:27:24 PM
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I drive a Prius (in Europe) and as you say the delay isn't really an issue with a hybrid. There is though a noticeable change of torque as the ICE kicks in and this can be annoying if it happens while cornering but you get used to it.

There are still quite a few cars around with manual transmissions here and they can take forever to pull away, sometimes so long that the traffic lights change before cars behind get through (lights can have quite short cycles here). Fuel is so expensive that people don't want to waste it on an automatic transmission. So stop/start might actually be faster as well as cheaper in that situation.

outdoors
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This is nothing new
outdoors   12/30/2013 6:35:04 PM
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Ever go golfing.  They have been using this technology in Golf carts for decades.  To me this makes sense. 

Bert22306
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Re: start stop is no news in EU
Bert22306   12/30/2013 6:43:56 PM
Where gasoline is very expensive, like Europe, it was not unheard of that people turned off their engines at red lights. Whether or not their vehicle was "start-stop."

One thing you didn't explain, Junko, is how you keep the heater or air conditioner running, when the engine is off. In practice, many/most/all(?) hybrids do not stop the engine if you are running either heat or air. Try it on any car. Turn off the engine at a stoplight, either during cold weather, or while it's raining and the windshield is fogging up, or on a hot summer day. With the interior fan running just on battery power, see well this works. Not very well! The heater core cools down very quickly when the (mechanical) water pump isn't running, and the blowing air warms up very quickly when the (mechanically driven) air compressor isn't running. I haven't seen either electric water pumps or heat pumps used in regular or hybrid cars just yet! I'm not sure how safe an electric water pump would be, for that matter. (Possibly, it could be designed to run on battery power only if the car is stopped, but that would put a heavy load on that battery.)

These days of computer-controlled machinery, this all can be made intelligent enough. But then, what this really means is that often, the engine won't turn off. Or if it does, not for long.

prabhakar_deosthali
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retrofiiting start-stop for the older vehicles
prabhakar_deosthali   12/31/2013 8:19:41 AM
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As far as the current technology cars , or slightly old cars for that matter ,are concerned ( I am using an Opel Corsa), even if I want to , I do not switch off the engine at the red signal.

This is because of the fear that the engine may not start quickly enough when the signal turns green and I would hearing the honking of the cars behind because of that delay.

 

I would love if this automatic start-stop mechanism can be fitted to the old cars ( with good starter motors!)  as they are not as fuel efficient as today's cars .

 

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