[C320-list] Multi Stage Voltage Regulator for Stock Alternator Possible?

[Warren Updike]

There are others on this list with more knowledge and experience than I, so,
for what it's worth here are my 2 cents: (my thoughts as they occur)

 -- The pattern of how we use our boats should determine the value of any
upgrade.  We are retired cruisers who typically take 2-3 week cruises as
well as weekends. We prefer to be on the hook, mooring, or slip in that
order, so having ample power is important.  My comments are based on this
pattern of use.
 -- I'm not sure what you mean by "charging efficiency." The stock
alternator will only put out what it is capable of putting out. A 3-stage
regulator will not make it put out more. It's interesting to note that the
output of a 55A alternator may not generally exceed 35A once the normal
operating temp. in the engine compartment is reached. These devices are
sensitive to ambient temperature.
 -- A 3-stage regulator will give you better control over the charging of
your batteries than does the integral regulator. Of course, this will only
occur for depleted batteries after a significant amount of run time as they
reach absorption and float stage.  I'm not sure a new regulator would make
your alternator work any harder.
 -- To connect an external regulator to your stock alternator may require
that you break the connections to the internal regulator and extend the
field wire outside of the body so it can be connected to the external
regulator.  This is probably something you will have to pay an appropriate
shop a fee to accomplish. 
 -- To get the value out of a 3-stage external regulator, you really need to
have a hi-output alternator, something that can output at least 50A on a
continuous basis.  The objective is to recharge the batteries quicker making
better use of the motor time we typically experience on a cruise.  The
regulator alone won't do that.
 -- Your Yanmar probably sports a 1/2" belt which is capable of driving a
100-120A alternator.  Such an alternator will probably be able to give you
75A continuous output.  The state of charge of your batteries will determine
whether they can accept this level of charge.  Usually, the charge
acceptance rate of a 350-400A bank will not be that high for very long.  My
experience, after an alternator/regulator upgrade, is that the rate of
charge drops to 40-50A rather quickly.

The moral of my story is that you are probably wasting your $$$ to install a
3-stage charger without also improving the output of your alternator.

Warren & Pattie Updike
1994 C320 #62 "Warr de Mar"

-----Original Message-----
From: Utility Email [mailto:kswanson123 at comcast.net] 
Sent: Thursday, February 10, 2011 6:50 PM
To: C320IA List Server
Cc: David Swanson
Subject: [C320-list] Multi Stage Voltage Regulator for Stock Alternator
Possible?

I have a stock 55 watt Hitachi alternator in my 320. I am interested in
installing a separate 3 stage aftermarket (Balmar or similar) voltage
regulator while disconnecting the integral stock voltage regulator to get
more charging efficiency out of the stock alternator. 

As many of you may know, the 3 stage voltage regulator and related wiring
are not inexpensive ($200 to $300). I am trying to avoid the high cost of
swapping out a perfectly good (albeit inefficient) stock
alternator/regulator for a new $800 Balmar (or similar) assembly. 

I have heard that if I do this, I will likely burn out my stock alternator
because the 3 stage voltage regulator will make the Hitachi alternator "work
too hard."  Is this true?  I imagine that the stock alternator would have
more load for a longer time for the bulk charging phase compared to stock,
but I guess that I am questioning whether this would significantly decrease
the life of the stock alternator.  I am also guessing that if I ask the
Balmar folks, they would say it would significantly decrease the life of the
Hitachi alternator because they want to sell me one of their heavy duty
Balmar alternators.  Once the bulk charging phase is completed, it seems
like the alternator load with an aftermarket multistage regulator would be
similar to the stock regulator.  So my questions:

1.  Has anyone upgraded their Yanmar 3YM30 engine mounted alternator to
perform efficient multistage charging without dropping $1000 to $1400 on a
new Balmar alternator and regulator?  

2.  How far off base am I?  Or is it possibly practical to just upgrade the
stock voltage regulator on our boats to improve engine driven charging
efficiency?

Any and all advice and experience with this would be helpful. 

Thanks!

Dave Swanson
S/V Emily Ann
2007 C310 MK II, No. 1107
Mukilteo, WA