[rudolphs]

I left off the Exciter wire when replacing my 1984 Universal Catalina 30 alternator with a new 51 Amp Sierra 18 6263 "Internal Regulator" alternator. The new belt is extremely tight; two brand new 105 Ah Walmart EverStart batteries. The prior and very suspect alternator/wiring had no exciter wire, so I left the new Sierra-supplied Exciter wire in the box. Now I'm seeing intermittent "no charging". Some days I'll go out and run the engine in idle for most of a 4-hour trip and find that my house battery has discharged during the entire trip. Need to switch batteries to start. Also, I seem to need to rev the engine once to "wake up" the new alternator. For load I run a small GPS and VHF Radio, which I've measured with a current clamp to be drawing 1.3A combined.

When the alternator is producing, I've measured it outputting 14.67V at full throttle between the positive terminal of the starter to ground. FYI, I have added a beefy shortcut lead from the alternator output to the positive battery terminal to bypass the long run to the console and back. Without the shortcut lead I only see 13.8V at the same test location.

Was I dumb to leave off the Exciter wire? Would the purple fuel pump power wire be a good candidate for T-connecting into the EXC. terminal of the alternator. I've attached a picture as currently wired as well as the Mando wiring diagram that came in the Sierra box. And a digression: if you happen to know, which terminal should the tachometer be connected too, again I could have wired it wrong, currently tach wire is connected to "indicator light" but I also tried it on "A/C TAP Tachometer" to no avail - I think my tach guage is caput.

Main problem is intermittent charging. Should I wire fuel pump wire to EXC.? Thanks in advance for all help, help, help.

As currently wired:

Mando Wiring Diagram that came in the Sierra box:

 

[deniseO30]

Welcome to sailnet! I went through this last summer and installed a self exciting alternator, it cuts in when engine is up to speed. So it would seem you already know what to do! Fuel pump could go through a oil pressure switch, I think that indicator light provides the resistance needed to excite the alt, maybe Sierra's wire has a resistor?

 

[MarkSF]

According to a quick search, the exciter wire should be connected to the ignition + which provides the excite. This is probably the reason you have to rev it to start charging. Im surprised it ever charges at all. Theres no reason it should, without excite.

"Was I dumb to leave off the Exciter wire?" I prefer the term "ill advised"!

Also, i believe that the sense wire should run separately to the battery, so that it gives a true reading of battery voltage to the alternator without carrying any current and hence having any voltage drop.

Finally, the tachometer connects to, wait for it, the tach connection.

 

[MarkSF]

I just realised something! Whys the fuel pump connected to the alt +? It should go to the ignition +!

Do you have a Universal 5424? Heres the manual which includes wiring diagram.

http://www.ewmanchester.com/CalDocs/Universal Diesel_5411_5416_5424_5432_Owners Manual.pdf

On the wiring diagram purple is excite. What a mess. Id check all the wiring and put it right.

If that really is fuel pump, that means its always on. No wonder your batteries go flat.

Edit : the wiring diagram might confuse you into thinking purple is fuel pump, as it says fuel pump above the wire. However, the fuel pump is ABOVE.

 

[SimonV]

I maybe blind but where is your negative wire.