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ivan&alice

Alternator suddently not putting out voltage... help!

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I ran my engine to charge my batteries this evening. When I started the engine up my voltmeter on my 110Ah leisure battery jumped from 12.4V up to 13.8V, which is about normal. I only noticed when I turned my engine off an hour later that my battery voltage had dwindled to 11.9V. I was running the fridge and USB chargers while charging, as usual, but the drop in voltage seems consistent with the alternator not putting anything in for that hour.

I turned the engine off for half an hour and stopped consuming electricity. I started the engine up and the voltage hovered around 12.0V.

There is a bit of a squeak from the belts that started a couple of weeks ago. And the belt driving the alternator looks a bit worn. I checked all the connections and everything seems fine, although the one cable rubbed part of its insulation off on a vibrating part.

 

Do you have any ideas for what could have caused this? What should I check? Should I call a boat electrician in the morning or are there some things I can try first to diagnose the problem?

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10 minutes ago, Murflynn said:

you have already diagnosed the most likely problem - tighten the alternator belt.

That and tape the wire up.

 

What engine/alt is it?

Is the charging light lit on the panel when you turn ignition on?
Does the light go out when running and is there a faint glow?
This will help others diagnose the problem.

My Vetus alt did a sudden death last year and it was a faulty (corroded) diode in the control panel. 

Edited by Guest

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19 minutes ago, Murflynn said:

you have already diagnosed the most likely problem - tighten the alternator belt.

 

11 minutes ago, catweasel said:

That and tape the wire up.

 

What engine/alt is it?

Is the charging light lit on the panel when you turn ignition on?
Does the light go out when running and is there a faint glow?
This will help others diagnose the problem.

My Vetus alt did a sudden death last year and it was a faulty (corroded) diode in the control panel. 


Thanks guys. No there is no charging light. I can normally tell when charging because the voltage jumps up. I have a split charge relay. Usually when turning the engine on the voltage remains in the low 12V range (I presume while the starter battery is charging) and then jumps up to around 14V. When I turn the engine off it dips down to 13.6V ish (which I believe is surface charge) and then settles down to around 12.9V. We make sure to charge before the battery shows 12.1V, which the battery manufacturer states is around 50% charge.

The engine is a Beta 38 (BV1505). Not entirely sure what alternator it is, in fact that is something I have been trying to find out. This 120A one looks identical:

https://www.ebay.co.uk/itm/LAND-ROVER-ALTERNATOR-300TDI-120-AMP-12V-YLE10113-MARELLI-TYPE-BRAND-NEW/264251686055
 

This looks like a 100A version: https://picclick.co.uk/Landrover-Land-Rover-Discovery-300Tdi-300-Tdi-100-361716748179.html
 

This is what mine looks like:


image.png.962682714d4d6b7d113785d9ba2638c5.png



 

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42 minutes ago, ivan&alice said:

When I started the engine up my voltmeter on my 110Ah leisure battery jumped from 12.4V up to 13.8V, which is about normal.

 

42 minutes ago, ivan&alice said:

the drop in voltage seems consistent with the alternator not putting anything in for that hour.

Your first statement seems to contradict the second one. 

 

22 minutes ago, catweasel said:

Is the charging light lit on the panel when you turn ignition on?
Does the light go out when running and is there a faint glow?

 

3 minutes ago, ivan&alice said:

No there is no charging light.

Ever?  So it’s not lit when you turn the ignition on?  If that’s the case then either the bulb is blown or you have a wiring fault, and the alternator is unlikely to excite (start outputting). 

 

 

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24 minutes ago, WotEver said:

 

Your first statement seems to contradict the second one. 

 

 

Ever?  So it’s not lit when you turn the ignition on?  If that’s the case then either the bulb is blown or you have a wiring fault, and the alternator is unlikely to excite (start outputting). 

 

 

I read it there isnt a lamp fitted, I didn't have one on my last alternator. 

 

31 minutes ago, ivan&alice said:

 


Thanks guys. No there is no charging light. I can normally tell when charging because the voltage jumps up. I have a split charge relay. Usually when turning the engine on the voltage remains in the low 12V range (I presume while the starter battery is charging) and then jumps up to around 14V. When I turn the engine off it dips down to 13.6V ish (which I believe is surface charge) and then settles down to around 12.9V. We make sure to charge before the battery shows 12.1V, which the battery manufacturer states is around 50% charge.

The engine is a Beta 38 (BV1505). Not entirely sure what alternator it is, in fact that is something I have been trying to find out. This 120A one looks identical:

https://www.ebay.co.uk/itm/LAND-ROVER-ALTERNATOR-300TDI-120-AMP-12V-YLE10113-MARELLI-TYPE-BRAND-NEW/264251686055
 

This looks like a 100A version: https://picclick.co.uk/Landrover-Land-Rover-Discovery-300Tdi-300-Tdi-100-361716748179.html
 

This is what mine looks like:


image.png.962682714d4d6b7d113785d9ba2638c5.png



 

Is the starter battery charging, if so it may just be a duff split charge relay

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4 hours ago, ivan&alice said:

Should I call a boat electrician in the morning or are there some things I can try first to diagnose the problem?

 

There is plenty you can do to diagnose the problem. The first thing you can do is buy a DC clamp meter last week, for immediate use whenever an electrical fault (such as this) crops up. 

 

Clamp it around the big fat wire coming from the alternator and see what charge current you have. You need to measure and tell us current as well as voltages. Measuring voltages alone only gives you half the story, and we (or you) cannot determine with certainty what is going on.

 

What current do you get?

 

 

 

 

 

 

Edited by Mike the Boilerman

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I'll punt that the *one* 110Ah battery you have been using for 6 months as your only battery is sulphated to hell and is only fit for weighing in for a tenner.

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9 minutes ago, TheBiscuits said:

I'll punt that the *one* 110Ah battery you have been using for 6 months as your only battery is sulphated to hell and is only fit for weighing in for a tenner.

 

Ah yes I'd forgotten about that. The sudden onset of this problem would suggest otherwise though.

 

 

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11 minutes ago, Mike the Boilerman said:

 

Ah yes I'd forgotten about that. The sudden onset of this problem would suggest otherwise though.

Plate short?

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11 hours ago, WotEver said:

Your first statement seems to contradict the second one. 

Sorry I wasn't clear.

 

Normally: When not cruising I charge twice a day. The voltmeter at this stage usually reads between 12.1V and 12.4V. When I start the engine, the voltage jumps up to around 13.8V. After an hour or so I turn off the engine and the voltmeter drops to around 13.2V for some time (surface charge). Then after a half hour or so it settles to be around 12.8V.

 

This time: The voltage read about 12.2V. I turned on the engine and the voltage jumped up to 13.8V as usual. I turned on the fridge and my USB chargers as usual. I wandered off and came back after an hour. I noticed the voltage was at only around 11.9V. I don't therefore know at what point the voltage dropped down from the usual 13.8V while charging. I turned off the fridge and chargers and the voltage went up to 12.0V. I opened up the engine bay to see what was happening and I saw nothing untoward. If I had left the fridge on for an hour _without_ the engine running, I'd expect the voltage to have dropped by about the same amount. So therefore I think that soon after I started the engine, the alternator stopped charging.

 

11 hours ago, WotEver said:

Ever?  So it’s not lit when you turn the ignition on?  If that’s the case then either the bulb is blown or you have a wiring fault, and the alternator is unlikely to excite (start outputting).


Again I wasn't clear. I do not have a charging light or any light on the ignition. The only way I can tell that the alternator is charging is because the voltage on the battery jumps up.


 

 

8 hours ago, Mike the Boilerman said:

There is plenty you can do to diagnose the problem. The first thing you can do is buy a DC clamp meter last week, for immediate use whenever an electrical fault (such as this) crops up. 

 

Clamp it around the big fat wire coming from the alternator and see what charge current you have. You need to measure and tell us current as well as voltages. Measuring voltages alone only gives you half the story, and we (or you) cannot determine with certainty what is going on.

 

What current do you get?

Great, this is really helpful. I have a cheap multimeter but I think it only measures up to 10A.

 

Would you be able to recommend a meter? What specs am I looking for?

 

8 hours ago, TheBiscuits said:

I'll punt that the *one* 110Ah battery you have been using for 6 months as your only battery is sulphated to hell and is only fit for weighing in for a tenner.

That's quite possible. I've been pretty dedicated to keeping the voltage above 12.1V which is what the battery manufacturer recommends. But as I've said before this battery is a disposable, temporary "trainer" battery to tide me over until I install proper electrics. I think also you might be surprised at just how little electricity we use. The only thing we ever run off the battery are our freshwater pump, lights and a bit of USB charging. The fridge, bilge and shower pump (and most of our charging) we only do with the engine on. The battery will get replaced in the next month or two regardless.

 

8 hours ago, Mike the Boilerman said:

Ah yes I'd forgotten about that. The sudden onset of this problem would suggest otherwise though.

Agreed the sudden onset seems to evidence against this.

 

8 hours ago, TheBiscuits said:

Plate short?

Could this occur from sulfation?

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14 minutes ago, ivan&alice said:

 

Normally: When not cruising I charge twice a day. The voltmeter at this stage usually reads between 12.1V and 12.4V. When I start the engine, the voltage jumps up to around 13.8V. After an hour or so I turn off the engine and the voltmeter drops to around 13.2V for some time (surface charge). Then after a half hour or so it settles to be around 12.8V.

 

If an hour's charging raises the at-rest voltage from 12.1V to 12.8V then I don't think your battery has much capacity left.

 

Only charging for an hour or two at a time is a sure fire way to wreck batteries. You should be charging for something like 8 hours continuously at least once a week.

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4 minutes ago, David Mack said:

 

If an hour's charging raises the at-rest voltage from 12.1V to 12.8V then I don't think your battery has much capacity left.

 

Only charging for an hour or two at a time is a sure fire way to wreck batteries. You should be charging for something like 8 hours continuously at least once a week.

 

Unless one has lithiums, obviously. 

 

Release from the onerous need to charge for such long periods weekly or buy replacement batteries regularly, is the spectacular benefit of having lithiums. 

 

 

 

 

 

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Problems solved!

Thanks @Mike the Boilerman you were correct. In the light of day and properly suited up I was able to see that the bolt that fixes the alternator fast had worked its way loose and was lying in the bottom of the bilge. I replaced it and tightened up the belt and voila, we're back up to charging at 14.2V.

 

Sorry for the panic and I really appreciate the prompt advice.

 

1 hour ago, Mike the Boilerman said:

Thanks! I actually want to measure the amp output of the alternator because I at this point don't know whether it is the standard 70A alternator or a replacement 100A or 120A. This will be important information while planning out the electrics. This meter will suffice to measure the alternator output yes?

 

 

1 hour ago, David Mack said:

 

If an hour's charging raises the at-rest voltage from 12.1V to 12.8V then I don't think your battery has much capacity left.

 

Only charging for an hour or two at a time is a sure fire way to wreck batteries. You should be charging for something like 8 hours continuously at least once a week.

I charge for 2-3 hours daily in two blasts, and go for a long cruise each weekend, sometimes more. The battery is still serving its purpose quite adequately and it was only 60 quid. I'm prepared to toss it once the proper system is in place. I'd actually rather kill the battery than put more wear on the engine and disturb the neighbours with more charging than I do.

 

 

54 minutes ago, Mike the Boilerman said:

Unless one has lithiums, obviously. 

 

Release from the onerous need to charge for such long periods weekly or buy replacement batteries regularly, is the spectacular benefit of having lithiums.

As great as they are, I'm still not convinced that lithiums are the way for me. But they are on my radar.

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2 minutes ago, ivan&alice said:

 

As great as they are, I'm still not convinced that lithiums are the way for me. But they are on my radar.

 

If you cruise for long periods weekly then no, not much point. Your 2-3 hours a day (bet the neighbours love THAT!) would turn in 20 mins a day though.

 

 

 

4 minutes ago, ivan&alice said:

Thanks! I actually want to measure the amp output of the alternator because I at this point don't know whether it is the standard 70A alternator or a replacement 100A or 120A. This will be important information while planning out the electrics. This meter will suffice to measure the alternator output yes?

 

Yes. But not having to break the cable to insert a meter in series is the main benefit. 

 

 

 

 

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35 minutes ago, ivan&alice said:

Thanks! I actually want to measure the amp output of the alternator because I at this point don't know whether it is the standard 70A alternator or a replacement 100A or 120A. This will be important information while planning out the electrics. This meter will suffice to measure the alternator output yes?

Well the meter says it will do 400A so it is the right range, however, if you have only one battery, then that might not accept the full output of the alternator so you might not be able to determine exactly what unit you have. When taking the measurement you would need to turn all your power demands on and have the engine at more than tickover.

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47 minutes ago, ivan&alice said:

Problems solved!

Thanks @Mike the Boilerman you were correct. In the light of day and properly suited up I was able to see that the bolt that fixes the alternator fast had worked its way loose and was lying in the bottom of the bilge. I replaced it and tightened up the belt and voila, we're back up to charging at 14.2V.

 

Sorry for the panic and I really appreciate the prompt advice.

 

Thanks! I actually want to measure the amp output of the alternator because I at this point don't know whether it is the standard 70A alternator or a replacement 100A or 120A. This will be important information while planning out the electrics. This meter will suffice to measure the alternator output yes?

 

 

I charge for 2-3 hours daily in two blasts, and go for a long cruise each weekend, sometimes more. The battery is still serving its purpose quite adequately and it was only 60 quid. I'm prepared to toss it once the proper system is in place. I'd actually rather kill the battery than put more wear on the engine and disturb the neighbours with more charging than I do.

 

 

As great as they are, I'm still not convinced that lithiums are the way for me. But they are on my radar.

You currently have a 70amp alternator, what type of belt drives it?

Single vee belt, will only just drive a 90amp alternator, so not much better than what you have.

Multi vee (poly vee) much better for higher amp alternators.  But if not already fitted, can your engine take the different pulley?

 

Your charging regime, is not really enough to keep the current setup in good health, better to learn now how to keep cheap batteries happy, than to go to great expense, only to kill batteries even faster.  Solar panels will help greatly in summer, but you still need to generate enough in winter.  

 

Bod

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48 minutes ago, Mike the Boilerman said:

If you cruise for long periods weekly then no, not much point. Your 2-3 hours a day (bet the neighbours love THAT!) would turn in 20 mins a day though.

Wow that would be a big draw card! How would having lithiums save on charging time? Surely you still have to put in what you take out? Or would the lithiums accept a greater charge current or something?

It's pretty standard on visitors moorings for people to run their engines. We try to be as considerate as we can and religiously stick to the 8am/8pm rule. Luckily our engine is very quiet compared to some of the engines and generators I've heard.

 

51 minutes ago, Mike the Boilerman said:

not having to break the cable to insert a meter in series is the main benefit. 

Would you not still have to do that, otherwise how would the current flow through the meter?
 

16 minutes ago, PeterF said:

Well the meter says it will do 400A so it is the right range, however, if you have only one battery, then that might not accept the full output of the alternator so you might not be able to determine exactly what unit you have. When taking the measurement you would need to turn all your power demands on and have the engine at more than tickover.

Thanks yes I will make sure to put the maximum load on the alternator when I do the measurement.

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21 minutes ago, ivan&alice said:

Would you not still have to do that, otherwise how would the current flow through the meter?

The current doesn't flow through a clamp meter. You place the arms of the meter around a cable and it senses the magnetic field induced by the current flowing through the wire.

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34 minutes ago, ivan&alice said:

Or would the lithiums accept a greater charge current or something?

 

Yep. Lithiums will suck it p as fast as any equipment you might install can deliver it. This is WHY peeps obsess about them!

 

35 minutes ago, ivan&alice said:

Would you not still have to do that, otherwise how would the current flow through the meter?

 

Nope. This is why clamp meters are nearly as brilliant as lithium batts!

 

 

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4 hours ago, Mike the Boilerman said:

Don't get a cheap one, many don't measure DC current via the clamp.

This one is about the best available, for boating needs.

 

Bod

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