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From: John De Armond
Subject: Re: The Power Quest Continues
Date: Mon, 17 Jan 2000 16:39:31 EST
Newsgroups: rec.outdoors.rv-travel

Mickey Lane wrote:
> Neon John <> wrote:
> >My last post had to do with making the decision between 12 volt and
> >24 volt systems.  I wanted the 24 volt version but alas, there
> >simply isn't enough room for a 24 volt alternator in the engine
> >bay.  Indeed, space is going to be the single biggest problem.
> I think I read recently on sci.chem.electrochem.battery that the auto
> industry is considering scrapping the traditional 12V system
> for something like 47V. 47 seems like a weird number but that's
> what my CRS enabled brain spits out. I didn't go into the story
> in detail.

It's 42 volts and it is a done deal.  Should be on the market within
5 years.  Just read an industry trade rag whose whole issue was
dedicated to the topic.  The initial motivation was to cut down on
conductor and battery size as the loads (thin film heaters for
defrosters and such) increase.  The driving factor now is the
eliminating of valvetrains and cams and directly drive the valves by
electrical (pure electrical or electrohydraulic) actuators.  Also
driving the movement is the desire to decouple accessory loads from
the engine for increased fuel efficiency.  The alternator will be
directly coupled to the engine (a la the water pump on late model
'vettes) and all other loads (power steering, AC, etc) will be
driven by electric motors.

Other benefits include being able to build a brushless starter into
the flywheel.  This will perhaps eventually also be used as the
alternator.  This enables the instant start engine that does not
idle, but starts and stops instantly as needed.

I'm not completely sure of all the reasons for the selection of 42
volts but one reason reported in the SAE journal was that the
internal detonator voltage in (some|all) airbag systems is 42 volts
and so there are already automotive qualified electronic components
available in production.


From: John De Armond
Subject: Re: Electric Drive Accessories?
Date: Tue, 19 Jun 2001 04:16:05 -0400

Robert Hancock wrote:

> I don't think any are in production yet, but I don't think it will be too
> long. I'd say they'll be using a 42 volt battery, I can't see any practical
> way of converting it up or something..

It will be a 36 volt battery.  The 42 volts is the operating voltage
fully charged, just like 13.8-14 volts is the operating voltage of
the 12 volt battery.

All accessories including the AC will be electric.  There will be no
power takeoff on the other end of the engine from the transmission.
At least that's the way it is being written up in SAE papers.


From: John De Armond
Subject: Re: Electric Drive Accessories?
Date: Sat, 16 Jun 2001 02:27:23 -0400

pyats@texas.neXt wrote:

> ray wrote:
> > Was daydreaming a couple of days ago, and started to think about
> > the accessories driven off the engine - water pump, a/c compressor,
> > power steering etc.
> >
> > Could you take all that off, and only have one BIG alternator mounted
> > on there?  (200 Amp or bigger?)
> (snip)
> Those items take horsepower to run.  The a/c would require a
> 3 to 5 hp. electric motor.
> One hp = 746 watts.  At 12v. thats 62 amps.
> Five hp would require 310 amps.  ...
> The wires would be about the size of your wrist and add
> several tons to the weight of a vehicle. ...
> Along with the 5000 amp alternator and the 500 hp gas turbine
> needed to run it...

Which is why this concept is not being implemented at 12 volts.  The
coming (within a couple of years) 36 volt nominal/42 volts operating
system that all new cars will soon have makes electrically operated
accessories easy to implement.  Indeed, this is the major reason for
upgrading to high voltage.  This allows the elimination of parasitic
drag on the engine when the accessories are not actually doing
anything.  No need to turn the power steering pump, for example,
when the wheel is straight ahead.

The alternator and starter will be one and the same and incorporated
in the flywheel/pressure plate.  Very similar to a stepping motor,
the device generates when the engine is running and it cranks the
engine when driven like a stepping motor or brushless DC motor.

There has been tons of papers published by SAE on this topic in the
last few years.


From: John De Armond
Newsgroups: rec.outdoors.rv-travel
Subject: Re: ISA engines to be available to consumers in 2005
Date: Thu, 11 Mar 2004 16:19:34 -0500
Message-ID: <>

On 11 Mar 2004 08:54:17 -0800, (El Alumbrado) wrote:

>Bob Giddings <> wrote
>> "A handful of automotive component makers are developing new systems
>> that will shut a car's engine during traffic tie-ups, then restart
>> it...
>Isn't it true that start-ups are the most damaging part of an engine's
>operating cycle, causing the most wear? Wouldn't this system cause an
>engine to endure vastly more start-up/shut-down cycles than is
>currently the case? Wouldn't the engines wear out much faster? Seems
>like that would overwhelm any small percentage gains in economy.
>What am I missing?

there are several ways of addressing this.  One is to have an oil reservoir
that is valved in right before turn-over to lift the bearings and prevent
metal/metal contact.  Another is to spin the engine electrically with a
compression released to minimize the initial pressure on the bearings.  A
variation is to initiate the vehicle motion with the electric motor and turn
on the gas after motion is established.  Yet another method is to keep the
engine slowly rotating during the 'stop" period, enough to maintain oil films.

One must remember that the maajor cause of startup wear on a conventional
engine - gas on the cylinder walls - won't be present here because the engine
will be rotated before fuel injection is commenced.

This has been a cause celebre in the trade press for several years.  All the
Tier 1 suppliers (visteon, delco, etc) have products advertised on their web
pages.  A major impediment remains the failure to agree on a 42 volt standard
(36 volt in common vernacular.)  It is quite difficult to transmit the
necessary power at 12 volts.

Despite all the spin in the press, after studying this in some detail and
talking to engineer friends inside major car companies, what I expect to see
is this implimented as part of a parallel hybrid system.  Only a high voltage
motor is capable of developing enough power to move the vehicle immediately
upon accelerator press while spinning up the engine.  I don't believe people
will accept even the second or so delay required to spin up a gas engine and
engage the transmission.

Just some idle speculation on my part, of course.


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