Battery-Charging Regulator Problem ? MasterVolt Problem ?

[RJV]

My yacht has three battery circuits - one for the engine starter, one for the house system and one for the bow thruster. It also has a Mastervolt Alpha Pro regulator (separate to the alternator) and a sophisticated Mastervolt battery monitoring system.

On occasions (sometimes several times per hour) I noticed the battery charge light on the standard Yanmar engine instrument panel illuminate - sometimes it will stay on for a minute or so, other times it will stay on for an hour or more. When this light illuminates, the engine tachometer also falls back to show zero RPM. A look at the battery monitoring system at this time confirms that the batteries are not being charged. As I make short voyages of two to four hours only and I can use sails I have not been too troubled by this .... each day I reconnect to shore power so the batteries will then be fully recharged.

My batteries are all in good condition, and the battery terminals are also all clean and tight. It would seem to me that the alternator is working OK, so I'm guessing that the Mastervolt Alpha Pro regulator has an intermittent fault. Am I on the right track, or could it be something else?

Sometimes when I am returning to my berth I discover that the bow thruster (MaxPower 100 Combi) won't work. I've figured that this problem is related to the above problem as on the occasions the bow thruster does not work the battery charge light on the instrument panel is illuminated.

My thinking here is that the control circuit for the thruster is wired to batteries other than the thruster battery bank (i.e. the engine, or more likely the house bank) ..... apparently this is good practice to wire this way ..... and if the voltage for the control circuit falls below a certain threshhold then the thruster will not energise.

On Friday I motored for four hours and the charge light stayed off for the entire time, but then as I slowed (from 2,000 RPM to 600 RPM) to reverse into my berth the light came on and my bow thruster would not operate .... just when I need it !

If I'm right then my "two problems" are connected .... but what is causing this. Is it a faulty Mastervolt Alpha Pro regulator?

[cal40john]

My first guess would be a slipping alternator belt. Many diesels get their tach signal from the alternator, so a slipping belt messes up the tach signal and your batteries aren't getting a good charge.

John

[RJV]

Originally Posted by cal40john

My first guess would be a slipping alternator belt. Many diesels get their tach signal from the alternator, so a slipping belt messes up the tach signal and your batteries aren't getting a good charge.

John

Thanks John. I also thought this might be the cause, but I checked the belt and although it showed no signs of slippage I retensioned it anyway, and the above described problems persisted. So it wasn't a loose belt to blame.

[Albro359]

Sounds like maybe you've got a loose earth connection from the alternator to the instrument panel ...the charge light on and the tacho not working at the same time

Or maybe theres an internal problem with your alternator ?

Cheers

Alan

[CharlieJ]

For troubleshooting advice, go to the Balmar site and take a look at the MC612 regulator manual. They provide excellent step by step troubleshooting procedures for the alternator and the regulator.

Part of your story is not making sense to me. You report that your bow thruster battery does not see charging current for some period, but the battery discharges enough so that the thruster is inoperable at the end of a short cruising day. If this is the case, you probably have a failed thruster battery.

[RJV]

Originally Posted by Albro359

Sounds like maybe you've got a loose earth connection from the alternator to the instrument panel ...the charge light on and the tacho not working at the same time

Or maybe theres an internal problem with your alternator ?

Cheers

Alan

I sort of dismissed the loose earth/loose wire theory as when the charge light comes on (and when tacho also reads zero) it does so for several minutes or hours at a time ..... not flickering etc. as one might expect if a wire was making intermittent contact. But I will check the wiring and earths again.

It still seems to me to be a regulator (or alternator) fault. The Mastervolt Alpha Pro regulator has a microprocessor which controls three stages of battery charging - bulk, absorption and then float. I'm no expert but my hunch is that something is going awry with this process.

[CharlieJ]

Here is the link to the Mastervolt manuals for your regulator and alternator:Alpha Pro 12 V (three-stage) « Alternators & Charge Regulators | Mastervolt. The world‘s leading brand in maritime, mobile and solar energy solutions. Use these specifics with the troubleshooting procedures on the Balmar site that I posted earlier and you will be able to isolate the problem to the regulator and/or the alternator.

You still have an undefined problem with your thruster battery that is going to have to be sorted out.

[RJV]

Originally Posted by CharlieJ

For troubleshooting advice, go to the Balmar site and take a look at the MC612 regulator manual. They provide excellent step by step troubleshooting procedures for the alternator and the regulator.

Part of your story is not making sense to me. You report that your bow thruster battery does not see charging current for some period, but the battery discharges enough so that the thruster is inoperable at the end of a short cruising day. If this is the case, you probably have a failed thruster battery.

Thanks for the pointer to the Balmar site - I've had a quick read and, yes, I will do these tests when I'm next at the marina.

As to the bow thruster part I can clarify. The bow thruster motor is wired to its own dedicated pair of batteries which are both in good order. The control circuit to operate the bow thruster (i.e. engage a relay which then connects the above batteries to the thruster motor) is wired to other batteries .... fairly sure this is the house batteries.

I don't believe that the thruster batteries are discharging at all - my battery monitor shows that they start with and keep good voltage whilst I am out cruising for a few hours (makes sense because I don't use the thruster).

But if, when I return from a cruise, I endeavour to use the bow thruster AND the charge light is on (which it typically will be at reduced RPM) then the bow thruster becomes inoperable.

If I put the boat's gearbox in neutral and rev the engine sometimes I can "tickle" something and the charge light will go off and at that minute I can use the bow thruster ... hence my reasoning that the bow thruster batteries are good, and the control circuit voltage is perhaps too low (or zero) .... caused by (at that minute) an intermittent fault in either the regulator or alternator?

[Albro359]

If you're sure the wiring is OK..then :

Charge light on means ...no output from the alternator..
that could be because :
a. its not spinning (belt) ... easy to check
b. there's no field current coming from your regulator to make it put out ie regulator broken
c. the alternator is "broken"

You can check the alternator by disconnecting the field wire at the alternator and connecting a 12 v lamp..say 15Watt or so between the battery positive and the field connection on the alternator and then start the engine.
The lamp will give you an amp or so of field current which will be enough for the alternator to start putting out current...your battery monitor should tell you this and the charge light should go out.

If that happens, the alternator is OK..its the reg thats the problem.

If nothing happens then its the alternator.


Tacho not working..
Does your tacho feed come from the alternator ?

I have a Yanmar 3QM30 and the tacho connection is at a sensor on the flywheel housing at the rear of the engine, not the alternator.
I have had problems with the tacho not working in the past and it has been this connection being intermittent.

Good luck !

[RJV]

Originally Posted by Albro359

If you're sure the wiring is OK..then :

Charge light on means ...no output from the alternator..
that could be because :
a. its not spinning (belt) ... easy to check
b. there's no field current coming from your regulator to make it put out ie regulator broken
c. the alternator is "broken"

You can check the alternator by disconnecting the field wire at the alternator and connecting a 12 v lamp..say 15Watt or so between the battery positive and the field connection on the alternator and then start the engine.
The lamp will give you an amp or so of field current which will be enough for the alternator to start putting out current...your battery monitor should tell you this and the charge light should go out.

If that happens, the alternator is OK..its the reg thats the problem.

If nothing happens then its the alternator.


Tacho not working..
Does your tacho feed come from the alternator ?

I have a Yanmar 3QM30 and the tacho connection is at a sensor on the flywheel housing at the rear of the engine, not the alternator.
I have had problems with the tacho not working in the past and it has been this connection being intermittent.

Good luck !

Thanks for this .... also very helpful.

I'll also do these tests.

My engine is a Yanmar 4JH4-HTE and according to the manual (alternator schematics and engine/instrument wiring schematics) the tach sensor is in the alternator (which is a Hitachi LR180-03C). But I'll check the wiring to see that it is indeed wired as per the manual.

Interesting - I spotted the following in a Mastervolt Alternator and Regulator manual. It refers to connections to a Mastervolt alternator, whereas mine is an Hitachi, but there are similarities to the symptoms (no tach reading at certain times).

Connection of a tachometer (optional)

If a tachometer is used, it should be connected between the W terminal of the alternator (see reference 8

) and the B– terminal of the alternator (or the NEG pole of the battery). See figure 9.

NOTE!
With some alternators the W terminal is marked by an “R” instead of a “W”

NOTE!
The operation of the tachometer can not be guaranteed when the Alpha Pro regulator switches from absorption mode to float mode. Switching on some loads during operation will solve this problem.

[Albro359]

That Hitachi alternator originally came with a built-in auto style regulator...to work with your 3-stage regulator, thsi in-built reg needs to be removed so the external reg can supply the field current...maybe a stupid question...but has this system ever worked properly ????

[RJV]

Originally Posted by Albro359

That Hitachi alternator originally came with a built-in auto style regulator...to work with your 3-stage regulator, thsi in-built reg needs to be removed so the external reg can supply the field current...maybe a stupid question...but has this system ever worked properly ????

I know exactly what you mean. The yacht is 2 years old and I've owned it for the past year only. The Mastervolt Alpha Pro regulator etc. was all there when I purchased the yacht and it worked just fine for me until three months ago when things started to go wrong. So I am pretty confident that the Hitachi alternator has had its in-built regulator either removed or disabled.

I'm not adverse to calling in a marine electrician to address the problem - its just that I would be up for about 2 hours travel time (an hour each way) for each call out .... so I'm trying hard to first pin point the problem to either repair it myself, or narrow things down so that I can avoid multiple call outs (I doubt a marine electrician carries the required 3-stage regulator or alternator with him all the time).

I'm more than capable of adjusting or replacing the regulator and/or replacing the alternator .... if only I could determine which was at fault.

[Simon Beaven]

My Alpha pro regulator when it is near the end of a charging cycle 75 to 80% starts to over voltage, the engine room is warm then too (can go as high as 17 volts) i guess its not going into float? but i have adjusted this potentiometer with no affect. I am normally charging at 14.2 volts into a large bank of gel cells.
Is there something quite silly that Im overlooking, I have checked terminals for corrosion and replaced the sensor connector which was corroded (could this be a problem when the engine room warms up)

[goboatingnow]

OP, AT a guess, you either have a faulty or internittent Alpha pro reg or check all the field connections between the Alpha an the alternator. It looks to me like the regulator is at time dropping the field current and the alternator is shutting down, this would cause the tacho to fail and the charge light to come one as well.

Simon Beavan, your problem suggest a dead Alpha, it doesntg seem to be regulating the output at all. When the batteries are low , the battery resistance will mean the alternator is current limited hence the voltage will stay down, once you enter absorbsion phase , the alpha should begin to regulate the voltage. Check that it is connected to the battery 12v and neagative, if their ok, then the alpha is not.

[Captain Bill]

RJV, how big is your house bank? How much load do you have on it? It makes no sense to me that your bow thruster won't energize if your alternator is not putting out. It's pretty hard to drain a fully charged house bank in a couple of hours under normal load conditions. Most battery protection circuits don't cut off until the battery voltage is pretty low. The alternator light simply means that your alternator is not charging the batteries, not that the batteries are disconnected from your equipment. Unless the house bank is 80% or more discharged you should be able to energize the thruster. Do you have manual battery disconnect switches? If one of these has gone bad it could disconnect you batteries from everything. It would probably cause your alternator light to come on as well.