Re: (ET) "42 volt systems"

["RJ Kanary" <rjkanary nauticom net>]

Larry, how are the engineering types dealing with the other problems that
higher DC potentials bring with them? Like arc suppression in switches and
contactors. Some automotive trade journals have had some impressive 
pictures
of what happens to the 'state of the art' automotive switchgear, when
exposed to the 36V nominal / 42V charging, system.


RJ Kanary
Member TRNi  Since 1998
ASE® Certified Master Auto Technician

rjkanary nauticom net

----- Original Message -----
From: "Elie, Larry (L.D.)" <lelie ford com>
To: "'Neil Dennis'" <wombat RealNS com>; "Elec-trak"
<elec-trak cosmos phy tufts edu>
Sent: Friday, June 07, 2002 11:44 AM
Subject: RE: (ET) "42 volt systems"


> Neil, Steve, everyone:  I am very familiar with the 'coming' 42V systems.
It was WAY oversold here at the automakers for about a decade but is still
coming.  I say oversold because it was touted as a 'more efficient system'.
Well, the wiring harness will be lighter.  That's about it.  It really is
just a way for some controls people to put in a bigger alternator.
Seriously, any magnetic-field delivering device is limited by the product 
of
the current and the number of turns of wire.  If you have more voltage, you
can use less current, but then you use more turns of wire.  It is a 
zero-sum
gain to within a fraction of a percent.  That said, the wiring harness can
be made lighter at a higher voltage, and the power electronics are lighter
and cheaper.  Yes, it 'enables' electric valve train, etc.; but only in 
that
we can now afford the electronics.  Yes, you can make a cheaper
starter-alternator; but if you want to pay for the tooling you could 
before.
Chrysler did it on a !
> 6V system in the 1930's.  Our alternators are 50-60% efficient because
they are CHEAP TO MAKE that way.  My bet is our 42V alternators will still
be 50-60% efficient because they will be CHEAP TO MAKE that way.  We can't
go much beyond 130A at 14V because the wire is too heavy to bend at
production levels.  THAT'S why we are upping the voltage.
>
> That said, there will be 42V chargers on the market soon.
>
> Cynically,
>
> Larry Elie
>
>
> -----Original Message-----
> From: Neil Dennis [mailto:wombat RealNS com]
> Sent: Thursday, June 06, 2002 5:10 PM
> To: Elec-trak
> Subject: (ET) "42 volt systems"
>
>
> Just finished reading an article about the coming "42 volt" automotive
> systems - sounded interesting.  Uses 36 volt battery and 12 volt battery
> with all kinds of "dream' stuff.  Maybe automotive will catch up with us
> and our antiques.  (;-')
>
> wombat
>