High Voltage under Power

[Sailing_Sona_Linn]

Sona Linn has a Universal 25 XP. The engine charging system seems to be "standard".  She has 200W of solar with a dedicated charge controller charging 270Ah house bank and separate starting battery. I noticed my cockpit volt meter reading above 15 while motoring last weekend- I checked the meter at the nav table and confirmed the same. While plugged into shore power, or under solar alone, I am between 13-14V which is normal. Any thoughts on the root cause? Voltage regulator? If so, where might I look to find it?

[Stu Jackson]

The ONLY 12V producing piece of equipment when motoring is your alternator, unless your solar controller is broken (but you've checked it already, you said).

ITWMB, I'd disconnect the solar from the house bank, and prepare to measure the AO (alternator output) voltage.  You do this either at the back of the alternator (best but you need either secure alligator clips or adding a wired ring terminal to the V+ post and a ground wire) or at the battery bank (other end of same wire, account for voltage drop in the wire).  Run the engine at cruising rpm out of gear, it won't hurt anything for a short period of time to do this.

If you haven't run your AO to the house bank bypassing the 1-2-B switch, then you could measure voltage at the C post of the switch.

It appears you just have the OEM alternator with internal regulator.  The regulator is built onto the back of the alternator.  If you still read high, bring it into a local alternator shop.

Good thing you check your instruments when motoring, good on you!

[waughoo]

I'm with Stu here.  The internal regulator might be out of whack.

[Sailing_Sona_Linn]

Thanks guys. I was at the boat this morning before I saw your response-I pulled the alternator and took it to my local shop here in town for a quick bench test. It was working as it should. I showed him the pictures of the connections (so I could remember where to reconnect) and he suggested that the PO may not have wired the connections properly to begin with. His main concern was there was nothing wired to the "Sense" post on the VR. I am going double check some of the diagrams on the forum and see if I can confirm correct connections. I know 2 of the three are right

[Stu Jackson]

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 and he suggested that the PO may not have wired the connections properly to begin with. His main concern was there was nothing wired to the "Sense" post on the VR. I am going double check some of the diagrams on the forum and see if I can confirm correct connections. I know 2 of the three are right

These may help, from when I upgraded to an external regulator.

Alternator Regulator Wiring Diagrams - all three http://c34.org/bbs/index.php/topic,4548.0.html

[Sailing_Sona_Linn]

I reviewed the diagram linked above and made a jumper from the battery to the sense post. I ran out to the boat tonight and reinstalled the alternator. It is working as it should. ~13.5-14 V on both volt meters. Thanks for the great info!

[waughoo]

Glad you got it sorted out!!

[KWKloeber]

Caution

Sona Linn has a Universal 25 XP. The engine charging system seems to be "standard". 

Realize folks that there is no such thing as "standard" when it comes to a boat, especially Catalinas.  When Universal was building engines trying to meet the high demand of boat manufacturers during the heyday they could use any part they could buy when another one was not available.  Supply chain issues happen not only during a pandemic!

In a dictionary, any dictionary, you will never see a picture of a Catalina, or any boat, next to "typical" or "normal" or "standard."
Really, I've looked.

Universal used 3 or 4 alternators that I know of, though most had the Motorola 8M2049K series (first picture) -- which are INTERNALLY sensed.  One of the optional 72a alts had external sense.  But one of the 55 amp Motorolas was also EXTERNALLY sensed -- the original wiring was to connect the SENSE to the AO (as I show 2nd pic) but of course, it's always better to sense right at the bank rather than at the AO.

Photos-photos-photos are always best when posting a problem. 
YOUR part is possibly not the same as SOMEONE ELSE's part.