Alternator problem

[3663Ian]

I have a problem with the Alternator on a Volvo Penta 2002 18hp circa 1985. I think the alternator is a Veleo A13N1M but I haven’t found any marking to confirm this, does anyone know how to positively identify the type? (I have not taken the alternator off the engine yet)

The problem is as follows:
When the ignition is turned on the charge light does not come on.
When the engine is started the alternator does not charge unless the engine revs are rasied above 2500rpm, after that it continues to charge normally regardless of revs.

I have done the following tests:
Checked the charge warning lamp....OK
Measured the Voltage at terminal 61 with the engine not running...... 11.5 Volts
Removed the wire form terminal 61 and connected it directly to -ve batt.....Charge warning lamp lights(as does the temperature warning light...I think this might be a normal feature to test the temp warning lamp or provide a second source of alternator excitation, I have read both explanations but I would be grateful if someone could clarify if this is correct please)
Connected a small 12 Volt lamp between +ve batt and terminal 61 of the alternator.....Lamp does not light, and alternator does not charge unless the engine revs raised to 2500rpm.
Checked the -Ve connection of the alternator to the engine block and to Batt -ve.....0 Ohms and 0 Volt drop (engine off, engine running but not charging and when charging)

My thought so far: (please check my logic)
The alternator appears not be getting excitation current and is self-exciting when the engine is run fast.
The control panel/charge warning light circuit, which should provide the excitation current, appears to be OK.
The alternator itself (rotor, stator, slip rings, diodes, regulator) appears to be working ok as the alternator charges OK once excited.

So I am thinking that the must be some break in the circuit between Terminal 61 on the back of the alternator and wherever this is connected internally inside the alternator. Is there anything inside the alternator that is specific to the part of the circuit?

Does anyone have any internal information on this alternator type?

I haven’t taken an alternator apart before so I would like to know what to expect and have whatever spares I might need before I take it off the engine.

Any ideas please?

Ian

 

[catmandoo]

I have a problem with the Alternator on a Volvo Penta 2002 18hp circa 1985. I think the alternator is a Veleo A13N1M but I haven’t found any marking to confirm this, does anyone know how to positively identify the type? (I have not taken the alternator off the engine yet)

The problem is as follows:
When the ignition is turned on the charge light does not come on.
When the engine is started the alternator does not charge unless the engine revs are rasied above 2500rpm, after that it continues to charge normally regardless of revs.

I have done the following tests:
Checked the charge warning lamp....OK
Measured the Voltage at terminal 61 with the engine not running...... 11.5 Volts
Removed the wire form terminal 61 and connected it directly to -ve batt.....Charge warning lamp lights(as does the temperature warning light...I think this might be a normal feature to test the temp warning lamp or provide a second source of alternator excitation, I have read both explanations but I would be grateful if someone could clarify if this is correct please)
Connected a small 12 Volt lamp between +ve batt and terminal 61 of the alternator.....Lamp does not light, and alternator does not charge unless the engine revs raised to 2500rpm.
Checked the -Ve connection of the alternator to the engine block and to Batt -ve.....0 Ohms and 0 Volt drop (engine off, engine running but not charging and when charging)

My thought so far: (please check my logic)
The alternator appears not be getting excitation current and is self-exciting when the engine is run fast.
The control panel/charge warning light circuit, which should provide the excitation current, appears to be OK.
The alternator itself (rotor, stator, slip rings, diodes, regulator) appears to be working ok as the alternator charges OK once excited.

So I am thinking that the must be some break in the circuit between Terminal 61 on the back of the alternator and wherever this is connected internally inside the alternator. Is there anything inside the alternator that is specific to the part of the circuit?

Does anyone have any internal information on this alternator type?

I haven’t taken an alternator apart before so I would like to know what to expect and have whatever spares I might need before I take it off the engine.

Any ideas please?

Ian

If you can find anything externally you might want to check the brushes . Potting compound on my alternator regulator directly mounted over the brushes partially melted and the sticky epoxy ran into the brushes preventing them making contact with the rings on the rotor . at worst it took 2 minutes before heat made the epoxy more fluid and allowed the brushes to make contact so while symptoms similar to yours it might be that there is some other thing wrong with the way your brushes make contact

 

[VicS]

The symptoms you describe and the results of the things you have tried have me puzzled.

i have repaired alternators when the problem has been obvious but i think this is one of those times when I would take it to an automobile electrician.

You may be right about the broken wire or it might be a regulator fault

Brushes / slip rings maybe but .... ?

 

[catmandoo]

The symptoms you describe and the results of the things you have tried have me puzzled.

i have repaired alternators when the problem has been obvious but i think this is one of those times when I would take it to an automobile electrician.

You may be right about the broken wire or it might be a regulator fault

Well said

 

[3663Ian]

Thanks

I realise now that I haven't measured the voltage on Terminal 61 with the wire disconnected and the alternator charging. I am going to do that, I guess if it is 14V then my broken connection theory is out the window. But if its 0V then I guess it's not something intermitent in the rotor -brushes regulator circuit.

I haven't tried to measure the resitance of termina 61 to -ve batt as I was not really sure what to expect. Any ideas what to expect?

 

[VicS]

Beware of volts readings made with a digital meter. they take so lttle current that you can often get a normal reading when you would not if they drew a bit of current.

No idea what the resistance is but it must be fairly low because the warning light would normally come on brightly.

Dismantling the alternator may require some seriously heavy unsoldering of the stator windings from the rectifier although you'll be able to access the regulator and brushes without.

Should look something like this

 

[pampas]

Measure the voltage on the warning light ciruit cable when disconnected. with engine stopped and ignition on, this will prove that circuit is ok. if not you will have to trace it back , either cable fault or ingnition switch.

 

[VicS]

Measure the voltage on the warning light ciruit cable when disconnected. with engine stopped and ignition on, this will prove that circuit is ok. if not you will have to trace it back , either cable fault or ingnition switch.

He says if he earths the lead the bulb lights.. That confirms that the ign switch the wiring and the bulb are OK

 

[ZEBEDEE]

The Alternator exitation is via the ignition warning light until it is producing volts, once this is happening then the lamp will go out as there will be no voltage across it. From the symptoms discribed a would think that there is a broken wire in the alternator or an open circuit field coil. You could check this with an ohm meter measure the resistance from the terminal to earth.

 

[William_H]

Alternators

Most alternators use current via the ign lamp to the regulator then to the slip rings and filed coil. Or in the so called negative regulator the current goes ign light slip rings regulator earth. Most alternators then when generating have a separate set of 3 diodes to feed Dc to the point where the ign lamp power feeds in. This then provides the excitation power making the current from the ign lamp redundant. OK you probably knew all that.
An alternator can sometimes generate enough charge to appear to be working from the residual magnetism in the rotor. That is when the field coil has no current. This will only be noticeable at high RPM.
So I think it possible that your problem is still bad slip rings /brushes. This is a common failure mode for alternators. Certainly worth a check.
No you won't need spares to remove and check. Although you could buy new brushes just in case. The slip rings can be cleaned with fine sand paper or similar. If the brushes have been giving trouble there is often burn marks on the slip rings. On most alternators this cleaning and replacement can be done with alternator removed but not dismantled beyond the brush /regulator housing.
good luck olewill

 

[charles_reed]

I'd suggest taking the alternator along to a competent auto-electrician and having it given a thorough test, on a bench.
My very similar symptoms were traced to an intermittent fault in the on-board regulator, easily rectified, within minutes, by replacing the part.
Unless of course you like solving puzzles...

 

[VicS]

The Alternator exitation is via the ignition warning light until it is producing volts, once this is happening then the lamp will go out as there will be no voltage across it. From the symptoms discribed a would think that there is a broken wire in the alternator or an open circuit field coil. You could check this with an ohm meter measure the resistance from the terminal to earth.

The fact that once the engine is up to 2500rpm it generates ok rather suggests that the field coil is not o/c.

I'd suggest taking the alternator along to a competent auto-electrician and having it given a thorough test, on a bench.
My very similar symptoms were traced to an intermittent fault in the on-board regulator, easily rectified, within minutes, by replacing the part.
Unless of course you like solving puzzles...

as I said much earlier

 

[Leonidas]

I'd suggest taking the alternator along to a competent auto-electrician and having it given a thorough test, on a bench.
My very similar symptoms were traced to an intermittent fault in the on-board regulator, easily rectified, within minutes, by replacing the part.
Unless of course you like solving puzzles...

Totally agree and add : Plenty of good quality rebuilt exchange alternators to be had.

 

[John100156]

I trust the OP dont mind me jumping in but:

One of my alternators needs new brushes on my TAMD63 engine, anyone know where I can buy the brushes from? See part 19 below - or do I need to pay the inflated price that a VP dealer would levy?

I suppose if the brushes are soldered-in to the regulator (not stripped it yet so dont know) I may need a whole new regulator Part No. 872720 - anyone stripped one of these down?

I have repaired alternators many moons ago and know how they work, but just need to know a supplier who can provide replacement brushes if possible!

Many thanks

 

[SAMYL]

I trust the OP dont mind me jumping in but:

One of my alternators needs new brushes on my TAMD63 engine, anyone know where I can buy the brushes from? See part 19 below - or do I need to pay the inflated price that a VP dealer would levy?

I suppose if the brushes are soldered-in to the regulator (not stripped it yet so dont know) I may need a whole new regulator Part No. 872720 - anyone stripped one of these down?

I have repaired alternators many moons ago and know how they work, but just need to know a supplier who can provide replacement brushes if possible!

Many thanks

Try these people:-

http://jcrsupplies.co.uk

 

[DavidGrieves]

Hi

I had the same proplem with my VP 2002 when I bought my boat last year. Wouldn't start to charge unless you gave it loads of throttle.

Do you have any smart chargers in the system or split charge diodes?

Mine had a sterling alternator to battery smart charger fitted (badly) by a previous owner. I think it wasn't working because the alt wasn't getting power from the batteries to excite its fields. If you have a split charge diode could this do the same thing?

This a bit from the Sterling instructions...

After you have started the engine, check the voltage at the main alternator input of the unit. You should be able to measure at least 13V. If you do not measure any voltage at all, it is possible that your alternator requires a voltage on the output to fire up. (See Extended Installation.) In this case connect an extra wire from the alternator-to-battery terminal named “STARTER SOLENOID” to the positive terminal of the starter solenoid.



Link to sterling PDF instructions...

http://www.sterling-power.com/image...or-to-Battery Chargers and Remote Control.pdf



Have a look at wire No4 on the advanced instructions.


I'll probabbly get shot down and torn up by some "elec engineer forumite" but I fitted the wire over a year ago and never had the problem again...

 

[John100156]

Try these people:-

http://jcrsupplies.co.uk

Have sent them an email - will let all know how I get on....

 

[lw395]

Sounds like either brushes or regulator.
Or possibly an internal wiring failure.

 

[VicMallows]

I'll probabbly get shot down and torn up by some "elec engineer forumite" but I fitted the wire over a year ago and never had the problem again...

No! ... won't shoot you down

But if Mr Sterling wrote his instruction manuals in a more precise and less condescending manner it might save a lot of time on this forum. (I actually think his physical products are well designed and manufactured at a decent price).