T&T: Dual alternator charging revisited

[Elliott Bray]

I appologize if you got this message earlier. I tried to send it earlier but
it looks like there was a gap in coverage.
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I followed the previous threads re:dual alternator charging with some
interest.
I would like to revisit the topic and elicit any comments.

My concern addresses two engines/alternators and a single house bank (altho
engine start batteries could come into play down stream).

At present I have a 75 amp Balmar alternator and a Balmar ARS III three
stage regulator on each engine.

My understanding of the voltage regulaing process is that while the rotor of
the alternator spins constantly, it only generates current and sends it
'down the line' when current is applied to the field coils of the
alternator. The voltage regulator energizes this field line when it
determines that the battery voltage (which it measures through a 'sense
line' falls into one or more areas of concern. As already discussed, with
two separate systems, one regulator will always (?) trigger before the other
and hence that alternator will always be on-line. It is my understanding
that this is also why my non-electronic tachs don't always see any
revolutions (but that is another topic).

I have looked at the schematic of the Balmar 'Centerfielder' and my simple
understanding of its function is to 'duplex' the sense line and feed it to
two independent voltage regulators, hence they both see voltages that tell
them to do something.

In an email to the list in 2005
http://lists.samurai.com/pipermail/trawlers-and-trawlering/2005-July/094084.
html

Gary Brobst said:
"I had a long discussion with a Balmar engineer before setting up my system
to have the alternators on both engines charging a single house bank.  The
conclusion was to use a single MaxCharge regulator to control both
alternators.  This eliminates all the problems with the centerfielder and
allows maximum output from both alternators.  If you are concerned about
redundancy, buy another MaxCharge and keep it in the spare parts box.
Please contact me if you need more details.  My system works great."

Peter Bennett provides an interface diagram:
http://lists.samurai.com/pipermail/trawlers-and-trawlering/2005-July/094094.
html


Is there anything I have missed?
Is there a good reason for not constructing Peter's box and having both
alternators charge all the time?



****************
Elliott Bray
M/V Letitia - Gulfstar 44 MC
www.loopcruiser.com
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