[Quietcars] Cars that shut off and start back up.

Thu Dec 30 13:25:45 UTC 2010

Hi,
Successful stop start vehicles need better, electrically operated accessories. Yes, some of the energy comes from regeneration but this is seldom enough to operate these accessories alone. One of the earliest lessons hybrid owner learn is regeneration is this is not the best path to high mileage compared to calmer driving. But start stop vehicles often have to run the engine to provide the additional energy needed.
Early Honda and Prius owners soon discovered their engine driven, air conditioner compressors, typically 2-5 horsepower, even impacted their mileage in the winter. The defrost cycle uses the air conditioner to dry the cabin air so breathing won't fog the inside of the windshield and windows. So the engine which even at idle consumes 2-3 horsepower from internal friction had to generate nearly twice as much power to also handle the compressor. 
This is even more important for vacuum operated, power brakes and hydraulic steering systems. So the earliest electric assisted brakes and steering were on hybrid electric cars as no one could accept the loss of power braking and steering when the engine is off. 
This transition from mechanically driven accessories to electrically driven is not just for 'start stop' but overall vehicle efficiency. For example, a mechanically driven air conditioner compressor has to deal with engines that turn from 1,000 rpm to 6,000 rpm. But an electrically driven compressor can be optimized with the motor to run at an optimum speed. Electric compressors are more efficient than the mechanically driven compressors including elimination of a seal for the power shaft so they have fewer leaks, fewer moving parts, and last longer.
Bob Wilson
> Date: Wed, 29 Dec 2010 18:35:00 -0500
> From: mrtownsend at optonline.net
> To: quietcars at nfbnet.org
> Subject: Re: [Quietcars] Cars that shut off and start back up.
> 
> So, does this mean cars withy start stop systems have to run the engine stop
> run accessories or are the accessories driven by electric power and then
> when the engine starts, is the battery or batteries recharged by the
> generator or the regenerative braking system?  
> 
>  
> 
> -----Original Message-----
> From: quietcars-bounces at nfbnet.org [mailto:quietcars-bounces at nfbnet.org] On
> Behalf Of Robert Wilson
> Sent: Wednesday, December 29, 2010 3:49 PM
> To: quietcars at nfbnet.org
> Subject: Re: [Quietcars] Cars that shut off and start back up.
> 
> 
> Hi Mike,
> 
> You may be thinking of Ford's announcement that they are going to install
> "start/stop" systems in all of their new vehicles in the next year or so.
> This is a first for Ford which has been using hybrid technology similar to
> Toyota (and in fact both had cross-patent sharing agreements.)
> 
> This past decade, GM sold mostly "Mild Hybrids" which we called "belt
> assisted" hybrids with this start-stop technology. Sad to say, the fuel
> savings claims from "start/stop" were and remain inflated. The "start/stop"
> mechanism is that once the foot left the brake, it would start the engine.
> The vehicle would not move forward until the engine was running. Even so,
> the time frame was within the time it takes to remove the foot from the
> brake and move it over to the accelerator, several tenths of seconds or
> more.
> 
> >From a technical standpoint, these 'start/stop' system are typically in the
> 5 horsepower region and use a modified alternator that can run as a motor.
> They have been just strong enough to spin the engine but never strong enough
> to sustain speed in electric mode. All electrical power had to flow through
> the crank shaft, the GM approach.
> 
> The Honda hybrid builds the electric motor into the flywheel assembly, the
> Honda Integrated Motor Assist. There is enough electrical power that in some
> speed regions, the 15 horse power motor could both spin the engine and
> sustain speed. The real advantage came from the low-end torque that allowed
> a smaller Honda engine to perform more like one the next size up.
> 
> The "belt assisted" hybrids were always on large displacement engines and
> did not use the alternator-motor for any appreciable efficiency gains.
> 
> One aspect of the "start/stop" systems is the need for accessories such as
> the air conditioner compressor, power steering, and even power brakes to
> operate electrically. This will provide additional noise as many Prius
> owners have learned when running the air conditioner in the summer.
> 
> Bob Wilson
> 
> ----------------------------------------
> > Date: Tue, 28 Dec 2010 18:15:50 -0500
> > From: mrtownsend at optonline.net
> > To: quietcars at nfbnet.org
> > Subject: [Quietcars] Cars that shut off and start back up.
> >
> > This is something that I'd posted to a guide dog list of Seeing eye 
> > handlers, as someone had posted about the fact that some cars will 
> > join the quieter fleet, meaning that they will turn off and again 
> > restart once the accelerator pedal is pressed after being idle for a 
> > time., this is only my opinion, so if anyone has any concrete evidence 
> > of such or has other information that disputes anything I'm saying and 
> > can show me through evidence that our passed quiet car legislation 
> > will be enacted sooner, please share. This is not meant to bash any 
> > one organization or throw water on the quiet car fire, but to be 
> > truthful, in any and all ways regarding this issue.
> >
> > Mike T
> >
> > Jenn, this is apparently what is proposed, and the fact is that this 
> > legislation that was passed in the house that was begun primarily by 
> > the NFB and then the ACB which collaborated to lobby for it, will NOT 
> > be enacted for a couple of years, at the very least, and there isn't a 
> > thing that we can do to get it through beforehand.
> >
> > There is testing that needs to be done, a solution to which noises or 
> > noise a car or vehicle should make and where the noise emitted device 
> > or devices should be placed And an agreement that each car 
> > manufacturer has to come on board with is not yet set in stone. Scary, 
> > but true, and this legislation doesn't just apply to the blind for 
> > their safety, but to every consumer, whether the be sighted, mobile 
> > without any impairment, etc. Just something to think about.
> >
> > "I am accustomed to hearing malicious falsehoods about myself...but I 
> > think I have a right to resent, to object to, libelous statements 
> > about my dog."
> > -Franklin D. Roosevelt
> > Mike Townsend and Seeing Eye dog Brent Dunellen, New Jersey 08812
> > emails: mrtownsend at optonline.net;
> > michael.townsend54 at gmail.com
> > Home Phone: 732 200-5643
> > Cellular: 732 718-9480
> >
> >
> >
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