HELP! Alternator or Regulator or....?

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DBG8492

Senior Member
Joined
Jan 16, 2023
Messages
281
Vessel Name
Sovereignty
Vessel Make
1986 Marine Trader 36 Sundeck
I have an alternator that tested good this morning. It's an old Delco modded probably a decade ago by an alternator shop in Fort Lauderdale that no longer exists. No idea how many amps it pushes, but it has an external regulator. In fact, there are two of them on the bulkhead in the engine room - assuming one of them was a "hot spare" put there by the PO just in case.

This one:
1717696810400.png


Transpo V1200...

The engine starts and runs well, but the alternator doesn't seem to be charging. Test start battery voltage before starting the engine and it's 12.5 volts. Test it after starting, no change. And the tach doesn't work either - upstairs or down. They will *sometimes* jump up like they're going to work, but then they fall back to zero - especially at idle.

This doesn't change no matter which regulator I use. Oh - and the only light that comes on on the regulator is the green one.

I just splashed so I haven't touched anything in there - not the batteries, not the wiring - nothing.

Is it a bad regulator and if so, what kind of "off the shelf" model can I buy quickly so I can get underway? Even if I have to (cringe) go to Worst Marine over in Fort Myers - I don't care...
 
Forgot to add that this is a Lehman/Am Diesel 136
 
I'm not sure what you mean by 'tested good this morning'.
Did you remove it and have it tested at a shop this morning?
 
I'm not sure what you mean by 'tested good this morning'.
Did you remove it and have it tested at a shop this morning?
Yes.
 
At this point I have tested both of the regulators on the wall in the engine room (both identical and same as the pic above.

With the alternator cable connected to *just* the start battery, the battery voltage doesn't change when the engine is running - no matter the RPM. And the tach is working, just not at idle. Once you give it a little gas, it will jump and hold around 1K RPM and above it's steady.

I am basically ready to get underway - but can't without charging at least the thruster batteries by alternator. We will be staying in marinas every night, so I can use my AC plug-in charger to charge the start and house batteries - but I need to make sure the thruster is getting charged when underway because even with two batteries on it, I'm sure it pulls a lot when in use and I'd rather not be without it.
 
I suppose I'm going to have to bite the bullet and call the shop and have them come check. They offered to do so, but I didn't want to spend $175 an hour without trying to figure it out myself.
 
Was there some reason you had the alt tested? I.e, no output?
Well, we splashed on Monday and when I started the engine, the old ProMariner ProIsoCharge was not working. I called their tech support and they said that if the lights didn't come on when the ignition was on, it was a dead stick. So - it's dead - okay...

Now, I'm trying to bypass that and just charge the thruster batteries with the alternator - but yesterday, when I tried, the voltage at the batteries was the same regardless of whether or not the engine was running. I checked the oil pressure switch and it closes at 7psi and passes 12v to the alternator field wire.

At that point, I figured it was the alternator so I pulled it and took it to E&R Rebuilders in Clewiston based on a recommendation from a friend in the yard. They tested it and said it was good to go. The next logical step up the ladder is the regulator.

We are in the water at the yard, taking up space on their tiny little dock. We were supposed to be underway Tuesday morning, but we're still here and I'm getting antsy because we're in the way as boats come in or go out. They haven't said anything yet, but I'm sure they're not happy and I would be much happier myself if I were underway.
 
I'm not an electronics expert but if you have 12+VDC at the field connection on the alternator I would expect some measurable charging to be happening, especially after having your alternator tested...
It's odd that the field LED on your regulator isn't coming on when it should, too.

To get you moving off the dock I would buy a replacement alternator first, preferably internally regulated to keep as a spare when you sort this out.
 
Obviously, double check all the engine and battery grounds.

I'm just stating the obvious but sometimes after a long time on the hard I have
left a switch or two off or on that I mis-remembered the proper setting position.
 
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I thought about buying an internally regulated alternator, but that would mean waiting until next week to leave unless I didn't want a tach. I thought maybe I could just buy an IR automotive alternator, but Brian at Am Diesel told me that they won't drive a tach unless I take them to the shop and have them add a post for it.

I can't stay here any longer.

We're going to just get underway tomorrow with the existing alternator connected to the thruster batteries. The first leg of this trip is the longest at 8.5 hours. The start battery will be driving the gauge lights and will need to start the main three times - once for leaving in the morning, and then two more times for the locks on Lake Okeechobee - I don't think that will fully discharge it. And if I have to, I can maneuver without a thruster - I did pretty well in my sailboat and we're docking inside the St Lucie lock at the campground so it's not a complicated situation. Once docked, I can use AC chargers to bring everything back to full for the next leg.
 
Our next big project once we're up north is to redo the entire electrical system, so if I have to limp up there, then so be it.
 
Also I am assuming you are aware to avoid disconnecting the alternator output cable any time the engine is running. That can toast the diodes in the alternator.
 
Yessir - I don't even like being in there when the engine is running, so all disconnects/reconnects are done with the engine off and the ignition key switched off as well.
 
Have you done these tests with your battery charger off? My tach behaves in a similar way, it doesn't really pick up until I bring the rpms up to 1000 then it seems to works all the way down to idle. I was doing some 12v checks and realized my alternator didn't seem to work until I realized I had my battery charger turned on. My checks made more sense when I switched the charger off. I realize they said your charger was dead but just wondering if you actually switched it off. With my charger online the alternator didnt see a reason to kick out supply volts. Good luck!
 
Yes.

I actually thought this was the issue yesterday - I had the AC-based charger on when I was doing the initial testing, so I turned it off. But, even with that charger off, the alternator is still not charging. It's the damnedest thing...

I have to believe it's something to do with the ProMariner device being out of the mix, but the folks at their support desk - very helpful by the way - don't think that's the case. And I can't explain why it would be - it makes no sense.

But that's the ONLY thing that's changed in this equation.

Just gonna leave the alternator hooked to the thruster batteries and see what happens tomorrow when we get underway.
 
You keep repeating you will leave the ALT connected to the thruster batteries. Are you saying that ALT charges the thruster batteries but not the Start battery. That is what it sounds like.
 
No. Sorry I am just at the end of my rope and talking noise.

As far as I can tell, it's not charging anything, but I was going to leave it connected to the thruster batteries just in case.

It's dumb - and no, I'm not doing it.

What we ARE going to do is wait an extra day to leave and get a small generator that we can run to charge the batteries when underway.

If I had gotten the on board genny fixed and running like I wanted, we would have that to charge the batteries. But I let myself be talked out of it because of time.

What I should have done on Monday when I realized this was happening is just went and bought a damned generator and we would be underway now...
 
I assume you've testing the alternator directly with a multi-meter (pos probe to alternator's positive output terminal, neg probe to ground)? It should be in the 14.5+ range (at/above engine high idle). If really low output, try disconnecting the field wire from the external regulator and retest the alt. If still no meaningful output, the alternator is likely toast.

If you have appropriate Alt output voltage, work your way "down" the line and re-test voltage at each junction point (shunt, fuse, etc.).

I find the following YT channel is a great resource for pretty much all things boating electrical: PacificYachtSystems

For additional charging system troubleshooting, checkout:
or
 
OP: Balmar has an excellent troubleshooting guide available on line for their regulators. I suspect your regulators are a spin off of the same technology so I recommend going through those steps.

BTW, the quickest test to determine if the problem is the regulator or the alternator is to disconnect the regulator’s field from the alternator and, with engine at a fast idle, apply 12VDC to the field wire on the alternator. This is known as “full fielding” and should only be done for a very short period, < 1 minute. If the alternator and its connections to the DC system are sound, the alternator’s output should jump to near its nameplate rating.
 
OP: Balmar has an excellent troubleshooting guide available on line for their regulators. I suspect your regulators are a spin off of the same technology so I recommend going through those steps.

BTW, the quickest test to determine if the problem is the regulator or the alternator is to disconnect the regulator’s field from the alternator and, with engine at a fast idle, apply 12VDC to the field wire on the alternator. This is known as “full fielding” and should only be done for a very short period, < 1 minute. If the alternator and its connections to the DC system are sound, the alternator’s output should jump to near its nameplate rating.
Hey Charlie!

Thanks for the troubleshooting tip. We left on what is supposed to be an 11 day trip this AM. Bought a small 2500 watt genny just in case, but the batteries did just fine.

This hop was one of the longest of the trip, so I think we will be good the rest of the way as long as we top them off every night.
 
Is the alternator putting out on the B+ cable to the regulators? Any other wires on the back of the alternator? Pics

Alternator may not be getting excited if there is no output on the boat and bench tested good.
 
Testing GOOD on the bench may mean it gives an output with full throttle revs on the alternator. Your symptoms are no output at low revs but has an output at mid to high revs. Did you specifically ask them to test at idle rpm? The one time I took an alternator to be tested, they spun it up to several thousand rpm in a vice, it produced an output, and they handed back as GOOD. From then on I just buy a new one and keep a good one as spare.
 
I'm not an electronics expert but if you have 12+VDC at the field connection on the alternator I would expect some measurable charging to be happening, especially after having your alternator tested...
It's odd that the field LED on your regulator isn't coming on when it should, too.
I thought this was a good suggestion. Have you tried it. Attach 12v + to field and then see if ALT is putting out >13v, should be 14.4v on most IIRC. If it is, then the regulator is the problem.
 
Right now we are underway and I haven't tried anything. We bought a small gas genny to run if we need to run the AC charger while cruising.

Our first day was a 7 hour trip and the batteries held up fine. That's the second longest day we had planned. The next day, the behavior was the same so nothing has changed. There is no charge regardless of engine RPM except for the tach - it doesn't work at lower ranges when I first start the engine, but it does work at all ranges once we've been underway for a while.

The alternator worked at all RPM ranges. I watched them test it.

Due to weather in Florida, we are probably going to have to stop for an extended period today or tomorrow so I will resume troubleshooting then. Wherever we stop, it will probably be for a couple of weeks so I can order another alternator and voltage regulator and just wholesale replace everything because right now, I don't trust any of it.
 
Charlie's suggestion to full-field the alternator is a good one. There is a similar test that might be easier to do, which is to measure the voltage at the field terminal on the alternator. It will range from 0 to battery voltage, and indicates how much output the regulator is calling for. Battery voltage is full output, and is what you are doing when you do Charlie's test. But you can also just measure the field voltage without removing any wires or doing any jumpering which might be easier.

You should see a field voltage very close to battery voltage. If not, work back to the regulator to figure out why. The regulator could be bad, or it could be that it's not getting power (power feed to it is surely fused, so check that), the "ignition" input to the regulator isn't on which will prevent the regulator from doing anything, or there is some other bad connection in the power or sense wires for the regulator.
 
Any chance of a picture showing the regulator and how it's wired. That appears to be a completely undocumented regulator, so I think changes are real good that it's just not hooked up correctly or that it should be junked competely. Besides, I don't know why you would replace an internaly regulator with an external one that is also fixed voltage. The whole point of going to an external regulator is to get multi-stage charging. Temp control too, but this regulator doesn't have that.
 
There is zero documentation for that regulator, but from what I can piece together from youtube, facebook posts, and other random info, the regulator isn't doing anything, which we already know. The green LED just says it has power. The yello LED comes on when the field is beign driven, and the orange comes on when there is stator output detected.

A first step would be to confirm power and ground to the device, and confirm that the ignition input is turning on/off with the engine key switch. I suspect there is no ignition signal, or that it's connected to the wrong terminal on the regulator. Based on one youtube video, the A terminal is Battery +, and the S terminal is the Ignition input. Also, some of the videos are saying that the Green LED only comes on if there is a fault - go figure, especially since the label says it indicates power on.

Sorry, but this is about as bootleg as a device could possibly be.
 
I'm posting a listing for a Balmar regulator that looks nearly identical to the OP's.
There is a 24V version that looks identical, too.

This makes me think his is a 'TRANSPO' branded knock-off or maybe a counterfeit.
I notice that the OP's is listed at around $100 less than the Balmar branded one.

Here is another one that is very similar except that it has more colors on the fins:
 
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There is zero documentation for that regulator, but from what I can piece together from youtube, facebook posts, and other random info, the regulator isn't doing anything, which we already know. The green LED just says it has power. The yello LED comes on when the field is beign driven, and the orange comes on when there is stator output detected.

A first step would be to confirm power and ground to the device, and confirm that the ignition input is turning on/off with the engine key switch. I suspect there is no ignition signal, or that it's connected to the wrong terminal on the regulator. Based on one youtube video, the A terminal is Battery +, and the S terminal is the Ignition input. Also, some of the videos are saying that the Green LED only comes on if there is a fault - go figure, especially since the label says it indicates power on.

Sorry, but this is about as bootleg as a device could possibly be.
Yes - it is bootleg - as is the alternator. Like I said, the PO had the alternator built in a shop in Fort Lauderdale nearly twenty years ago. Based on that - and other things on the boat, he was a rather frugal person. If he were alive, I would ask him about it - but alas...

The alternator was in the spare parts bin when we bought the boat marked "Rebuilt 2006 - Tested Good" - and we used it because the one that was on the engine wasn't working. In his defense, after replacing the alternator when we bought the boat, this whole system worked until we splashed after being on the hard for nine months. Now suddenly, we are back in the water, and it's no longer working.

As I said above, there is power going to the Field Wire from the oil pressure switch. As soon as the engine starts and builds oil pressure, the switch closes, and 12V is available on the field side.

I just have a sneaking suspicion that this is all related to the ProMariner IsoCharge being dead when we splashed. Maybe that doesn't have anything to do with it, but it sure does seem quite coincidental.

My plan at this point is to get where I'm going, dock her, spend some time with family I haven't seen in nine months, and then come back and replace the alternator and regulator with new equipment from a well-know and well-liked vendor - rewiring everything involved in the charging system.

Would I like to get it working now? Sure - but I no longer have time to spend troubleshooting it as we are underway almost every day trying to get out of Florida before hurricane season ramps up. The little genny will power the AC battery charger underway if we need it.
 
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