Alternator wiring diagram

[moggyjo]

That is a slightly low charge voltage. Is there a shoreline powered charger on? It is certainly too high for a battery at rest, it may be down to meter innacuracy, but that would be a VERY innacurate meter. I presume the is actually a volt meter? Amps and volts being very different breeds of budgie.

I just had a thought should I have disconnected the live wire from the B+ before checking, I have a power line coming in but not to the batteries but I am using a battery charger that I disconnected while doing the test.

[Sir Nibble]

I just had a thought should I have disconnected the live wire from the B+ before checking, I have a power line coming in but not to the batteries but I am using a battery charger that I disconnected while doing the test.

No, you should not have disconnected anything but the charger, which as you say you did. We'll call that a positive test result then (the high voltage could be explained by the batteries having just come off charge). Are you certain sure cross my heart and hope to die that the warning light wire is correctly connected to D+?

[moggyjo]

No, you should not have disconnected anything but the charger, which as you say you did. We'll call that a positive test result then (the high voltage could be explained by the batteries having just come off charge). Are you certain sure cross my heart and hope to die that the warning light wire is correctly connected to D+?

Dont know how to say this just asked Moggy, he didn't re connect the D+ wire so I'll go and do it now,

[Sir Nibble]

Dont know how to say this just asked Moggy, he didn't re connect the D+ wire so I'll go and do it now,

I'll think of a way.

[moggyjo]

I'll think of a way.

Right it reads anything up to 0.52, any help

[Sir Nibble]

Right it reads anything up to 0.52, any help

What does? The voltage at D+?

[moggyjo]

What does? The voltage at D+?

Doesn't seem to read anything from the D+

[Sir Nibble]

Sorry, I think I must have come over all stupid. The voltage at B+ is 13.8, voltage at D+ is buggerall, where does the 0.52 come into it? This is SO difficult without being there!

[moggyjo]

Sorry, I think I must have come over all stupid. The voltage at B+ is 13.8, voltage at D+ is buggerall, where does the 0.52 come into it? This is SO difficult without being there!

Hello the 0.52 was the reading when I did not have the D+ connected

[Sir Nibble]

Hello the 0.52 was the reading when I did not have the D+ connected

Back tomorrow after a nights sleep

[Bones]

Sorry, I think I must have come over all stupid. The voltage at B+ is 13.8, voltage at D+ is buggerall, where does the 0.52 come into it? This is SO difficult without being there!

 

come and visit then! Moggy is up the way from here... I'll cook you a curry for afters....

[steelaway]

come and visit then! Moggy is up the way from here... I'll cook you a curry for afters....

 

JUST A MAYBE

 

Has the earth to the domestic batterys/alternater been disconnected. The starter circiut has it own (different) earth cable.

 

good luck

[Sir Nibble]

Well I've had a good look around and I cannot lay my hands on one of these alternators nor any worthwhile bits to play with. The reason I wanted to get hold of one is so that I could carry out some checks here. Let me explain. The bog standard alternator we have all come to know over the years have 6 diodes inside (think of a diode as a one way valve) to convert the generated AC into DC for battery charging, they also have an additional 3 diodes to supply current to magnetise the rotating field and require the small current supplied through the warning light to provide a wee bit of initial magnetism to this field.

Your alternator does not have these extra diodes but takes the field current direct from the B+ terminal. In order to only supply the field when the alternator is actually running there is an electronic circuit that detects the biddy little bit of AC generated as the unit begins to turn and switches on the field, one of these alternators requires only a B+ connection to work. Others, require that warning light current to "wake up" the electronics and say "Ignition is on get ready to go". I simply don't know which system yours employs.

The readings you give suggest the possibility that yours is of the second type and wants to see a voltage at the D+ terminal in order to function, but is not seeing sufficient to recognise. I suggest that the next step is to disconnect your split charge relay terminal 85 or 86 and try it again, the relay is connected to the same side of the warning lamp as D+ and is possibly "robbing" the alternator of the required signal.

I am getting splinters under my fingernails from scratching my head!

[moggyjo]

Well I've had a good look around and I cannot lay my hands on one of these alternators nor any worthwhile bits to play with. The reason I wanted to get hold of one is so that I could carry out some checks here. Let me explain. The bog standard alternator we have all come to know over the years have 6 diodes inside (think of a diode as a one way valve) to convert the generated AC into DC for battery charging, they also have an additional 3 diodes to supply current to magnetise the rotating field and require the small current supplied through the warning light to provide a wee bit of initial magnetism to this field.

Your alternator does not have these extra diodes but takes the field current direct from the B+ terminal. In order to only supply the field when the alternator is actually running there is an electronic circuit that detects the biddy little bit of AC generated as the unit begins to turn and switches on the field, one of these alternators requires only a B+ connection to work. Others, require that warning light current to "wake up" the electronics and say "Ignition is on get ready to go". I simply don't know which system yours employs.

The readings you give suggest the possibility that yours is of the second type and wants to see a voltage at the D+ terminal in order to function, but is not seeing sufficient to recognise. I suggest that the next step is to disconnect your split charge relay terminal 85 or 86 and try it again, the relay is connected to the same side of the warning lamp as D+ and is possibly "robbing" the alternator of the required signal.

I am getting splinters under my fingernails from scratching my head!

Hi Snibble,

Its working, a friend came round just now and what he did was put a small wire to B+ and D+ with engine running and the light went out and is charging now. He said it should work now without having to do that, if not he said he would have to put a bigger bulb on the charging light saying that maybe it might need that for more powerfull alternator,

Thank you ever so much for all your time and help,

Wendy

[Sir Nibble]

Hi Snibble,

Its working, a friend came round just now and what he did was put a small wire to B+ and D+ with engine running and the light went out and is charging now. He said it should work now without having to do that, if not he said he would have to put a bigger bulb on the charging light saying that maybe it might need that for more powerfull alternator,

Thank you ever so much for all your time and help,

Wendy

That's the one thing I was not going to advise, harmless and effective with the old 9 diode alternators but without knowing the internal circuit of the regulator it risks blowing out the warning light switching transistor in the regulator! I have since my last post got hold of a 2nd hand A127ir regulator and determined that the +ve brush is connected to the warning light terminal, so that's all right then. I have to assume that your mate either knows these units better than I do, or is a gambler, or had no idea of the risk! Bloody glad it's working now.

[moggyjo]

Blo***hell Batteries as flat as pancakes and this was almost as soon as I turned the engine off and just tried to fire up engine and the light wont go out! It all looked so good yesterday, what has gone wrong please.

I am just about to run out of power, neighbour is out so cant use his genny, got the BW Planning officer coming round at 11am and going off to a funeral at 1pm what a day and not even the sun to put some power into my solar pannels

[Sir Nibble]

Blo***hell Batteries as flat as pancakes and this was almost as soon as I turned the engine off and just tried to fire up engine and the light wont go out! It all looked so good yesterday, what has gone wrong please.

I am just about to run out of power, neighbour is out so cant use his genny, got the BW Planning officer coming round at 11am and going off to a funeral at 1pm what a day and not even the sun to put some power into my solar pannels

Do like what your mate said, higher wattage warning lamp.

[moggyjo]

Do like what your mate said, higher wattage warning lamp.

Hes just been round he said its beyond him, alternator is putting out half a amp with engine running light off batteries reading 13.50 and there abouts, he tightened up fan belt but made no difference, weird

[Chris-B]

Blo***hell Batteries as flat as pancakes and this was almost as soon as I turned the engine off and just tried to fire up engine and the light wont go out! It all looked so good yesterday, what has gone wrong please.

I am just about to run out of power, neighbour is out so cant use his genny, got the BW Planning officer coming round at 11am and going off to a funeral at 1pm what a day and not even the sun to put some power into my solar pannels

Is the Alternator/Wiring really requiring that ??

[Bones]

sounds like a complete nightmare! Is there anything I can do? I am at work at the moment, but I have a chum who isn't who may be persuaded to move my boat around if you can charge from that?

Edited January 10, 2008 by Bones

[Sir Nibble]

O dear oh dear, first and foremost, DON'T PANIC.

Check the voltage from alternator B+ to case, alternator D+ to case and battery + to - with engine running and alternator charging.

[chris w]

Hes just been round he said its beyond him, alternator is putting out half a amp with engine running light off batteries reading 13.50 and there abouts, he tightened up fan belt but made no difference, weird

 

The 13.5 volts out of your alternator regulator is too low to use on a narrowboat (it's for a car). You need around 14.2v in order to be able to charge the batteries effectively. Snibble may be able to supply one or failing that the alternator will need to be exchanged for one with a higher voltage regulator. That's why you are getting such a low current out of your alternator (assuming the alternator is working correctly otherwise).

 

Chris

[Sir Nibble]

Off the top of my head, I believe this alternator is regulated at around 14.9V! I suspect either a resistance between alternator and battery or multiple diode failure. Realistically, discharged batteries + 13.8V + 0.5A = does not make sense.

Edited to say that is is TOTALLY unnacceptable that anyone with such a cute avatar (Aaaaah bless) should be having these problems.

Edited January 11, 2008 by snibble

[moggyjo]

Bit hungver after yesterday, a car mechanic I know sugested that the ignition bulb being to small may be making the alternator not put out the amps, could this be right? if you think this could be the problem, what sort of bulb do I get? All the readings that Pete did yesterday were low said it was not worth running engine for half a amp

[Sir Nibble]

Bit hungver after yesterday, a car mechanic I know sugested that the ignition bulb being to small may be making the alternator not put out the amps, could this be right?

No, the bulb wattage will effect cut in speed but not output. I would expect that a voltage of 13.8V applied to a discharged 100Ah battery would push a current of around 20A, (Chris will be along in a moment to calculate it exactly for us). This is where I am having difficulty, If your battery is discharged, and the terminal voltage is reaching 13.8V, and this results in a charge of only 0.5A the only logical conclusion is really spectacularly knackered batteries. If this was correct, then the alternator should be driving up to it's regulated voltage which I cannot immediately quote with any certainty but should be significantly over 14V. This is where the problems arise, each reading gives the lie to the others, I really wish I had the time to come and look at this!!!

 

Go back to the meter, read the voltage at the alternator output, engine battery and domestic battery, let's see what difference, if any there is.