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hi all,i,m having problems with my alternator not charging,and i,m not sure what to look for in fixing this,i thought the alternator was broke so i bought a new one off ebay and this one did,nt charge either,someone suggested the alternator was,nt getting excited but i,m not sure how to check this,the alternator is fitted to a BMC 1800,any advice greatly appreciated, many thanks

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Without being able to identify the alternator.

 

As its a new one we can assume that you have tensioned the belt correctly.

 

Typically you will have one or two think wires (charge pos & maybe neg). Then one or two thin wires:

One from the warning lamp which is vital to energise the alternator and maybe one for the rev counter. If you get these on the wrong terminals it will not charge but no damage will be done.

 

There is also likely to be another 6mm blade connection "hidden" down a hole in the case that is for a radio suppressor - ignore this one and there may be a square suppressor fitted to it.

 

The terminal the warning lamp wire goes to is typically marked D+.

 

So, assuming two thin wires;

 

Turn the ignition on and keep an eye on the warning lamp. If it does not come on you probably have the two thin wires on the wrong terminals.

 

Pull a thin wire off and touch it to clean metal. If the lamp comes on its the warning lamp wire so it needs to og to D+

 

Pull the other wire off 9if you have one) and do the same. The lamp should not come on, that goes to the rev counter terminal that may be marked W.

 

If the warning light does not come on then the bulb has blown or there is a wiring fault related to the warning lamp.

 

If the warning lamp does not come one when the ignition is turned on but does when you earth the alternator end to metal then the alternator is faulty.

 

Please can we have a photo of the back of the alternator or tell us the make and model. Boats are not like cars and all are one offs so you could have anything there.

 

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The exciter current is via the warning lamp, no bulb, no excitement just boring. Bulb needs to be a filament not an LED unless a resistor is also fitted.

 

How did the lack of charge first show up? Was the lamp lit all the time? Did it come on with the ignition switch?

TD'

Edited by Tracy D'arth
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1 hour ago, Tracy D'arth said:
1 hour ago, Tracy D'arth said:

he exciter current is via the warning lamp, no bulb, no excitement just boring. Bulb needs to be a filament not an LED unless a resistor is also fitted.

 

How did the lack of charge first show up? Was the lamp lit all the time? Did it come on with the ignition switch?

TD'

 

1 hour ago, Tracy D'arth said:

The exciter current is via the warning lamp, no bulb, no excitement just boring. Bulb needs to be a filament not an LED unless a resistor is also fitted.

 

How did the lack of charge first show up? Was the lamp lit all the time? Did it come on with the ignition switch?

TD'

The exciter current is via the warning lamp, no bulb, no excitement just boring. Bulb needs to be a filament not an LED unless a resistor is also fitted

How did the lack of charge first show up? Was the lamp lit all the time? Did it come on with the ignition switch?

TD'

its an old engine fitted in a new boat,tight budget,and has never charged,rcr had a play with it said they fixed it but its not charging at all,i changed the warning light i could of put led in,i,ll check

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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38 minutes ago, dreadnought said:

its an old engine fitted in a new boat,tight budget,and has never charged,rcr had a play with it said they fixed it but its not charging at all,i changed the warning light i could of put led in,i,ll check

Its no just LEDs that are no good. Cheap all plastic warning lamps about 1/2" diameter that use a non-replacable grain of wheat (dolls house) bulb will also not pass sufficient current.

 

If you want a quick and dirty test of the warning lamp circuit get the engine running at about 1200 rpm or more and use a piece of wire to join battery positive (or the main positive output terminal) to the D+ terminal on the alternator for  a very few seconds. if it starts to charge its a warning lamp circuit fault.

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1 hour ago, Tony Brooks said:

Its no just LEDs that are no good. Cheap all plastic warning lamps about 1/2" diameter that use a non-replacable grain of wheat (dolls house) bulb will also not pass sufficient current.

 

If you want a quick and dirty test of the warning lamp circuit get the engine running at about 1200 rpm or more and use a piece of wire to join battery positive (or the main positive output terminal) to the D+ terminal on the alternator for  a very few seconds. if it starts to charge its a warning lamp circuit fault.

Do you have a multimeter to test things with?

If it has never worked even when RCR played with it the wiring could be all wrong.

I can explain how to wire it all up if need be.

TD'

 

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I would prefer the OP to identify the alternator before saying much more. Its unlikely but possible that he bought an ECU controlled automotive unit and if so he won't get it working.

 

I have given him two sets if tests and he has yet to report the results.

Edited by Tony Brooks

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I had almost exactly the same problem... new alternator wouldn't charge either. In the end it turned out I had the warning lamp and rev counter connections swapped (old alternator wasn't labelled). What really confused me was that the warning lamp went off when the engine was running as I'd expect. Not 100% sure after all that that the old alternator was actually broken but no way was I putting it back on to check!

 

Edited to add: I figured it out when I disconnected what I thought was the warning lamp connection and found zero volts between there and ground. Much swearing ensued.

Edited by phantom_iv

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Just now, phantom_iv said:

I had almost exactly the same problem... new alternator wouldn't charge either. In the end it turned out I had the warning lamp and rev counter connections swapped (old alternator wasn't labelled). What really confused me was that the warning lamp went off when the engine was running as I'd expect. Not 100% sure after all that that the old alternator was actually broken but no way was I putting it back on to check!

 

I expect the warning lamp would have been glowing if you cupped your hand around it because the rev counter terminal has a half wave rectified output of just one phase on it. However I have given the OP some tests to do that should  help sort that sort of problem out.

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22 hours ago, Tracy D'arth said:

Do you have a multimeter to test things with?

If it has never worked even when RCR played with it the wiring could be all wrong.

I can explain how to wire it all up if need be.

TD'

 

the wiring is a right mess really and i think thats the problem,i was thinking of buying a new loom and starting from scratch, ?

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22 hours ago, Tony Brooks said:

 

I expect the warning lamp would have been glowing if you cupped your hand around it because the rev counter terminal has a half wave rectified output of just one phase on it. However I have given the OP some tests to do that should  help sort that sort of problem out.

i,m hoping to do the tests that you gave next weekend,also the rev counter has never worked?

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22 minutes ago, dreadnought said:

the wiring is a right mess really and i think thats the problem,i was thinking of buying a new loom and starting from scratch, ?

If you look at the electrical notes on my website it will give you typical wiring diagrams for each section of the boat's system. Its no good buying a new loom if the alternator and charging system is not compatible and if its a single alternator engine it may well not be.

 

For charging its just 3 or four wires (2 or 3 if you ignore the rev counter) for a standard 9 diode alternator.

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I doubt that there is such a thing as a new loom for the average canal boat. Newer engines like Betas do have prepared looms but your BMC1.8D would have been wired in situ I would imagine. Not difficult, not many wires. Just wrapped in spiral wrap when completed.

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2 hours ago, dreadnought said:

i,m hoping to do the tests that you gave next weekend,also the rev counter has never worked?

If you alternator is not working the rev counter wont work

 

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On 24/07/2020 at 10:56, dreadnought said:

hi all,i,m having problems with my alternator not charging,and i,m not sure what to look for in fixing this,i thought the alternator was broke so i bought a new one off ebay and this one did,nt charge either,someone suggested the alternator was,nt getting excited but i,m not sure how to check this,the alternator is fitted to a BMC 1800,any advice greatly appreciated, many thanks

hi all,ive got an update on my charging problems,i went to my nb this weekend and tried the tests that tony brooks recommended,(many thanks tony)with no joy,i,ll try and upload a few photos and see if any body has any ideas,

20200801_131905.jpg

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On 24/07/2020 at 10:56, dreadnought said:

hi all,i,m having problems with my alternator not charging,and i,m not sure what to look for in fixing this,i thought the alternator was broke so i bought a new one off ebay and this one did,nt charge either,someone suggested the alternator was,nt getting excited but i,m not sure how to check this,the alternator is fitted to a BMC 1800,any advice greatly appreciated, many thanks

 

20200801_132306.jpg

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26 minutes ago, dreadnought said:

hi all,ive got an update on my charging problems,i went to my nb this weekend and tried the tests that tony brooks recommended,(many thanks tony)with no joy,i,ll try and upload a few photos and see if any body has any ideas,

20200801_131905.jpg

 

So its an Lucas A127.

 

What's that thin black wire clamped to the mounting bracket and ending on the case clamp nut.

 

It  looks like a newish alternator so is there by any chance a thickish black wire dangling about? Say about 8mm overall diameter.

 

 

What did each of those tests show? We need the actual results.

 

Now if that is the charge warning lamp you are holding either its not wired properly or the black wire magically turns into a blue one by the time it gets to the alternator - and alters its thickness. So when you pull the blue wire off the alternator and touch bare metal with the ignition on I bet the lamp says on when you pull the wire off.

 

Is one of the instruments  revcounter? If so I think the wiring  on the alternator has a wire missing and the blue wire may be on the wrong terminal. Trace the blue wire back to the panal

 

Edited by Tony Brooks

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4 minutes ago, Tony Brooks said:

 

So its an Lucas A127.

 

What's that thin black wire clamped to the mounting bracket and ending on the case clamp nut.

 

It  looks like a newish alternator so is there by any chance a thickish black wire dangling about? Say about 8mm overall diameter.

 

 

What did each of those tests show? We need the actual results.

 

 

 

the thin black wire is an earth wire i put on,no thick black wires hanging,the charging light was on all the time,the only time it went off was when i turned the panel board lights off on the toggle switch,the only wires hanging about is the old connector that has two meaty brown wires going to it ?

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9 minutes ago, dreadnought said:

the thin black wire is an earth wire i put on,no thick black wires hanging,the charging light was on all the time,the only time it went off was when i turned the panel board lights off on the toggle switch,the only wires hanging about is the old connector that has two meaty brown wires going to it ?

In which case the so called charge warning lamp is just another panel lamp. It needs rewiring to act as a warning lamp (the bulbs in those are normally OK power wise).

 

Trace the blue cable back from the alternator and see where it goes, it looks like a numpty wired it to me.

 

Alternatively rewire the bulb thus: Ign. Sw. On terminal > warning lamp terminal 1. Warning lamp terminal  2 > where the blue cable is on the alternator.

 

Then try the tests again. I bet with the ignition on the lamp will go out when you pull the water off the alternator and go back on when you touch it t metal and then  when you replace it. If so I bet it will charge.

 

PS - you had better trace the thick red wire and ensure it runs to the battery master switch if you have a split charge relay or to the split charge diode if you have one of those. Nothing can be taken for granted now.

Edited by Tony Brooks

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48 minutes ago, Tony Brooks said:

 

So its an Lucas A127.

 

What's that thin black wire clamped to the mounting bracket and ending on the case clamp nut.

 

It  looks like a newish alternator so is there by any chance a thickish black wire dangling about? Say about 8mm overall diameter.

 

 

What did each of those tests show? We need the actual results.

 

Now if that is the charge warning lamp you are holding either its not wired properly or the black wire magically turns into a blue one by the time it gets to the alternator - and alters its thickness. So when you pull the blue wire off the alternator and touch bare metal with the ignition on I bet the lamp says on when you pull the wire off.

 

Is one of the instruments  revcounter? If so I think the wiring  on the alternator has a wire missing and the blue wire may be on the wrong terminal. Trace the blue wire back to the panal

 

i took the blue wire and touched to metal and the light stayed on,the blue wire  disappears into the engine so i`m not sure how to trace it back,also i think your right about the light being wired up wrong but not sure how to find out 

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5 minutes ago, dreadnought said:

i took the blue wire and touched to metal and the light stayed on,the blue wire  disappears into the engine so i`m not sure how to trace it back,also i think your right about the light being wired up wrong but not sure how to find out 

 

Well just disconnect and insulate it and rewire the lamp. No one knows where it goes so you need to inspect every inch of the harness to see where it comes out and then use an Ohmmeter to confirm it the same wire or split the loom open. Alternatively just rewire it.

 

I think there may be a spare blade terminal on the ignition switch but get the correct set of blades. if there is not you can probably pick up an ignition on feed from the brown wire terminal on the back of a gauge.

 

As I said it looks very non-standard wiring to me so what else has been wrongly wired, we simply do not know.

Edited by Tony Brooks

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