Hello Frank:

This maybe a little long winded but I learned something neat here.

That's a good call having separate amp meters off each alternator.
I am sure one alternator will want to source most of the current, but
thats ok, as the second alternator will have to kick in when the load is
applied. When the load goes nutz-oid wanting a Bazillion amps I am sure
the output current will be close to equal, if the voltage regulators are
set close to each other.

While working as a marine technican/electrican for several years, in Los
Angles I was called to a boat having alternator problems. I talked with
the boat owner and came prepared with a new marine grade alternator and
regulator.

The boat had two engines and each engine had 2 alternators. As the
electrical system needed a redundant back up everything as it did
research and commercial work out at sea for long periods of time. Time
is money and money is time stuff here.

The owner said that when the Engine #1 auxiliary alternator was placed
on line the running voltage did not increase as with the normal main
alternator did. Same for #2 Engine.

Well as the engines where running the main alternator was carrying the
load and you could not see the auxiliary alternator come on line by just
looking at the systems 24 volt system voltage. After pulling off the
field wire from the main alternator, we verified the auxiliary
alternator was really working putting out the needed current to run the
boats 24 volt electrical system. The auxiliary alternators where placed
on line by a lever that over centered and locked into place tightening
the belt that turned the alternator pulley, pretty neat!

Ok so everything was working as we verified the alternators, batteries,
and had to replace a few battery connections. No big deal.

The owner asked me to check out the electrical system #1 and #2 cross
over operation.

The boat or really a ship had to have two of everything, Two: HF Radios,
VHF Radios, Lightening Systems, Engine Indicating Meters and Indicator
Clusters, CB Radios, and of course all of the Nav Electronics like
Radars, ADF, Loran, Depth Finder, Automatic Pilot, and bunches of other
stuff. Ok so every thing ran off the 24 volt system #1 or #2.

But they didn't know how the electrical system #1 and #2 crossed over or
ran the other system when one of the engines was shut down, and wanted
to know how to operate and test it out. I didn't know either as I
couldn't find a cross over contactor relay any where.

After looking over the ships wiring diagram, I saw the cross over
contactor or relay, it had to be turned on (by a switch in the wheel
house) to allow the two electrical systems to be tied together for high
current operation.

But the neat thing that I found was that the two electrical system where
tied together thru a calculated resistance, in this case a short length
of 8 gauge steel wire that would only allow so much current to flow
between the two electrical systems. This allowed the system #1 to be up
and running and be able to run a few things on system #2, and charge the
system #2 batteries, and visa versa. This also allowed the main system
running to not be pulled down by a short in the other system.

The electrical control panel in the wheel house showed all the
alternator voltages and currents. You where able to select which of the
3 battery sets to start the engines, pretty neat. They had a small 4
cyclender gas engine that ran again two alternators and a hydraulic pump
for a auxiliary back up. And a gas powered Honda Generator mounted just
aft of the wheel house to supply 12, 24VDC, and 115 VAC for a back up
back up. Neat stuff.

So a calculated resistance coupled connection between two alternators
would allow the alternators to run separated systems and allow say a
second alternator to back up the other system while not loading it
down. Food for thought.

Jay in the Mojave


Frank Gilliland wrote:

On Tue, 28 Dec 2004 04:11:38 -0800, Jay in the Mojave
wrote in :

snip

Is this advice from experience?



Actually, yes.

Ok I have not heard of this noise but will keep an ear for it.



Even better, install two ammeters (one on each alternator) and watch
how they -don't- share the load equally.


snip

Maybe that's why Motorola designated their cheap CB amp transistors as
MRF454 and MRF455 -- to appeal to the 'big engine' mentality.

Yeah I am sure thats possible, but the nerd linger who designates the
numbers I am sure sets behind a desk and has his car serviced by normal
people.



What's 'normal'?



I would have a number like MRF-HP/454CI-Inc. hehehehehhehe

Matched transistors would go by Balanced MRF-HP/454CI-Hipo Inc
Or even PT2M454-Hipo Inc (Pettle to the Metal) OH YEAH!



So if the amp has a cooling then it's got a 'blower'? Doesn't matter
since it probably wouldn't pass the emissions inspection. And the
bubble really bursts when you realize that it takes 3kW to equal the
power of a lawnmower engine. So throttle up that moped, Jay -- you be
ridin' with the big boys!