Catalina Mk II (1992) Alternator Regulator Issues

Jul 14, 2021
4
Catalina 30 Dartmouth Yacht Club
Hi, we have a new to us Catalina 30. I have attached an annotated photo, showing the relevant wiring.
While cruising recently, right after we installed two new start 1000MCA batteries, I took measurements at the battery terminals. Here are the results:
1700 rpm – 17.02 Vdc on terminals of start battery S2
1500 rpm – 16.40 Vdc on S2
1100 rpm – 13.85 Vdc on S2
I know these voltages are too high, so I am guessing the regulator may be off.
I could not find any name/model on the alternator, nor the voltage regulator. Does anyone recognise this alternator? I do not know if it is 51A, 55 A or larger.
The terminals are identified in the picture, as I could see them. I do not know if that will help identify this alternator/regulator combination.
I have been in contact with Balmar to see if they could suggest a new regulator to use - they suggested I start with the simple ERS-KIT ($50) to replace the existing regulator.
Any thoughts on what this alternator may be and any luck replacing just the regulator?
Thanks
Ken
Laveer
 

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Ward H

.
Nov 7, 2011
3,129
Catalina 30 Mk II Barnegat, NJ
Welcome to the forum, Ken!
My 93 C30 had a different alternator with an internal regulator so I'm not familiar with your set up. I do agree the voltages are high.

Forum member @Maine Sail, AKA Rod Collins, is a marine electrician and has an excellent how-to web site.
Here is the link: Marine How To. There you will will find many articles on marine electrical and other subjects.

Maine Sail is also a Featured Contributor on the Musings with Maine Sail forum (part of this site). Here is a link to a thread by Maine Sail on external regulators that you might find helpful. External Regulators

Hopefully he'll jump in on this thread and can answer your questions.
 
Jul 14, 2021
4
Catalina 30 Dartmouth Yacht Club
Thanks for the reply with the links Ward. It is forums like this that make the time thinking about sailing fun!

Ken
 
Feb 6, 1998
11,436
Canadian Sailcraft 36T Casco Bay, ME
#1 You have a Delco 12SI. If you are using it with an external regulator this means someone converted it to external regulation as Delco never made an externally regulated 12SI. Most shops that do this Mickey-Mouse the conversion because they don't have the components to do it professionally and in a professional manner. We very often see 10SI and 12Si's that have been converted to ER short internally. When this happens the alt can go full field and run the voltage through the roof or take out the regulator entirely.

#2 Your regulator is very, very old. The company that made it is long gone and it was a single-stage regulator that was no better than an internal regulator. It's seems very odd that someone would go to all that work only to use a cheap single stage regulator as the stock 12SI would do just about the same.

#3 Your issue could be a voltage-sensing problem. You'll need to figure out where the red regulator wire goes. If the boat has a diode-isolator, that regulator and alt combo it is certainly time to start over with an upgrade.
 
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Jul 14, 2021
4
Catalina 30 Dartmouth Yacht Club
Thanks for info Maine Sail. I went to your website and it is (after just scratching the surface) awesome!
Looks like I should plan to get a new alternator/regulator. I will have to look at the varius topics on your site as well as others in this forum to figure out what would be best option moving forward.

Ken
 
Feb 6, 1998
11,436
Canadian Sailcraft 36T Casco Bay, ME
Thanks for info Maine Sail. I went to your website and it is (after just scratching the surface) awesome!
Looks like I should plan to get a new alternator/regulator. I will have to look at the varius topics on your site as well as others in this forum to figure out what would be best option moving forward.

Ken
When we can get stators & rotors again we have the best values on externally regulated alternators you'll find anywhere. Pair one with a Balmar ARS-5H and you'll have a very nice system for very little boat bucks.
 
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