TWL: Re: 32 to 24 volt conversion
In a message dated 2/16/02 12:01:31 AM, Mike Maurice writes:
<< One of my engineer friends points out that cat and detroit 32 volts
starters are no different than 24 volt ones.
That the alternators are the same, but the regulators are different.
Since 32 volt equipment is real hard to find, but 24 volt stuff is
becoming lot easier, I am proposing a switch. >>
Starters are very short duty cycle motors and are wound with such heavy wire
that they almost impose a direct short on the battery. On a 12v. system, the
total resistance of the entire starter circuit, i.e. battery cable, starter
relay, starter, and ground connection, should be less than .025 ohms. The
nominal voltage rating of the starter makes little difference. What
determines starter current is generally the internal resistance of the
battery. Doubling the voltage to the starter to get added output is common
practice in cold parts of the country. That's about the only way you can get
a cold soaked diesel tractor started in Vermont. (There is an alternative
approach using a blowtorch but the less said about that, the better.) Voltage
doubling relays, sold in auto parts stores, temporarily hook two 12V.
batteries in series to provide 24v., then revert to a 12v. parallel
connection after the engine has started. It doesn't surprise me at all that
24v. and 32v. starters are the same beasts, although I'll bet the 32v.
starter costs more. The upshot is that if you run a starter for less than 30
seconds at a time, allowing it to cool for 2 to 5 minutes between starting
attempts, almost any 24 v. starter can be used on 32v. or vice versa.
Alternators can be made to produce much higher voltages than their rated
output. They are wound in such a way that the rated voltage is produced at a
relatively low rpm and limited to that voltage by the regulator. The limits
on alternator output are generally set by the current handling capacity of
the wires and by the internal diodes. For a while magazines like Popular
Mechanics offered instruction for do-it-yourself voltage raising techniques,
letting you pull 110v. from an ordinary 12v. alternator. Essentially the
instructions involved circumventing the regulator and replacing the diodes
with higher voltage units. There should be no difficulty in getting a 32v.
alternator to produce 24v. with a new regulator.
Of course you can wait a few years until the automobile industry converts to
32v. and use off the shelf items.
Larry Z
At 11:20 AM 02/16/2002 EST, LRZeitlin@aol.com wrote:
Of course you can wait a few years until the automobile industry converts
to 32v. and use off the shelf items.
Larry Z
REPLY
Don't bet on it!
When the automotive world switches to 36V ( 42V ) it will involve more
than a simple voltage adjustment.
The primary need for higher voltage is increased power demand, much of
which will be used by the all electronic engines and injectors etc.
Siemens has unveiled a "coaxial" regen type starter alternator rated at
around 8 Kw.
This all in one unit bolts to the crankshaft in place of the flywheel.
Feed it power and it acts like a motor and starts the engine.
When the engine is running and turning this device, it acts like a
generator and produces electrical power.
With air pollution and hydro carbon emissions being a primary concern,
the idea has been put forth that when a vehicle comes to a stop the
engine should be shut off. When you step on the "gas" pedal, the engine
is restarted and you drive away.
Except for drag racers this slight delay will not be noticed by the
average driver. However, experts have calculated that the total amount of
emissions will be reduced drastically by not having engines ideling at
stop lights etc.
Now don't shoot the messenger!
I'm just telling you what I have found out while investigating automotive
electrical developments.
I can see several benefits to this approach in terms of production cost
reduction, increased power, lower emissions etc.
However, such an engine will be completely different compared to what we
see now. Chances of doing a retro fit of the starter onto an older engine
is slim. At least until some company produces an adaptor kit with all the
necessary parts.
Cheers
Arild
Will a 32 V winch motor work on 24 V ? (A left over from the old 32 volt
system)
Bob Clinkenbeard
M/Y Twin Screws
1964 Chris Craft Roamer 56'
Under reconstruction in Savannah
----- Original Message -----
From: LRZeitlin@aol.com
To: trawler-world-list@samurai.com
Sent: Saturday, February 16, 2002 11:20 AM
Subject: TWL: Re: 32 to 24 volt conversion
In a message dated 2/16/02 12:01:31 AM, Mike Maurice writes:
<< One of my engineer friends points out that cat and detroit 32 volts
starters are no different than 24 volt ones.
That the alternators are the same, but the regulators are different.
Since 32 volt equipment is real hard to find, but 24 volt stuff is
becoming lot easier, I am proposing a switch. >>
elnav@uniserve.com writes:
the idea has been put forth that when a vehicle comes to a stop the
engine should be shut off. When you step on the "gas" pedal, the engine
is restarted and you drive away.
A few years ago the marina here obtained an open four wheel vehicle (looked like a big golf cart that worked exactly as you describe, except the motor/generator was belt coupled to the gasoline engine).
The vehicle was used by the marina to move people and parts. It had decent pick-up and acceleration. When the marina got it, it looked fairly beaten up, meaning it was a few years old even then.
Don't see, why something like that couldn't be built for highway use right now.
Cheers -- George of Scaramouche
The large anchor winch that is on my ex commercial fishboat has a 24 volt
aircraft landing gear motor in it and it runs on 12 volts. The speed is down
somewhat but that just gives more "gear" reduction to the whole assembly but
it sure does pull !! I would expect a 32 volt motor run on 24 volts to be
much the same.
John Tones MV Penta
Victoria BC