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Alternator suddently not putting out voltage... help!


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5 minutes ago, Mike the Boilerman said:

But Snibs has positively identified it as self exciting.

 

Have you tested the alternator in the dark? That 13.9v from your solar will be fooling your 14.0V regulator into turning the alternator OFF.

I wrote that before Snibs got involved! Thanks - I'm writing a reply to his questions now...

 

The solar turning the alternator off would explain it?!

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2 hours ago, Sir Nibble said:

What does this mean?

"In doing so I managed to loosen the terminal that comes out of the alternator. I thought I'd broken it completely but after removing the whole alternator I found that the bolt has a slotted head that just fits into the "face". I put it back together and the alternator was working."

I see no slotted heads and don't know what you mean by the "face".

 

The main output bolt had a very tight nut on it. When I unscrewed it, with some force, the whole bolt became loose. Naturally I thought I'd broken it completely.

 

I removed the alternator to get better access. Once I removed the black plastic cover from the back of the alternator I could see inside with difficulty. It turns out that the loose output terminal bolt has a "head" that has say a 20 point star. When you screw a nut onto the terminal bolt it draws the head into a 20 point star hole, preventing it from turning while you screw your lugs on. Here's a diagram...

 

image.png.e6b7a20da6d00ace3e9f9bc9cf2093a9.png

 

 

2 hours ago, Sir Nibble said:

If you can lay your hands on a small test lamp and connect it from +ve to D+ (the small terminal in the picture with the nut on) then let us know how it behaves.

I'll try find a test lamp, but for now I measured the voltage and there's a difference of 12.1V between the +ve output terminal and D+, if that helps?

 

 

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33 minutes ago, ivan&alice said:

  

 

The main output bolt had a very tight nut on it. When I unscrewed it, with some force, the whole bolt became loose. Naturally I thought I'd broken it completely.

 

I removed the alternator to get better access. Once I removed the black plastic cover from the back of the alternator I could see inside with difficulty. It turns out that the loose output terminal bolt has a "head" that has say a 20 point star. When you screw a nut onto the terminal bolt it draws the head into a 20 point star hole, preventing it from turning while you screw your lugs on. Here's a diagram...

 

image.png.e6b7a20da6d00ace3e9f9bc9cf2093a9.png

 

 

I'll try find a test lamp, but for now I measured the voltage and there's a difference of 12.1V between the +ve output terminal and D+, if that helps?

 

 

That voltage is to be expected. If you look closely at the main terminal stud, under the nut is a sleeve, under the sleeve is a wafer thin metal plate that carries current into the regulator. You wouldn't be the first one to fracture that. Check closely. I will post a picture.

233636.jpg&height=525&width=525&quality=90&Crop=5

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1 hour ago, Sir Nibble said:

That voltage is to be expected. If you look closely at the main terminal stud, under the nut is a sleeve, under the sleeve is a wafer thin metal plate that carries current into the regulator. You wouldn't be the first one to fracture that. Check closely. I will post a picture.

233636.jpg&height=525&width=525&quality=90&Crop=5

I didn't take the whole regulator off to check, because I started stripping one of the screws holding it on and I felt like i could see the metal plate quite well. It doesn't look fractured to me. Unless the fracture could be underneat the black plastic inside the regulator?

 

Here are some pics - let me know and I can take more. (As an aside, the alternator is filthy, it's full of soot from a past exhaust leak - the carbon doesn't dissolve in anything so I'm not sure how I can clean it or if I should).

 

IMG_20200414_154233.jpg.e191f4e8b097e3c4f6c17c5a765d89c1.jpgIMG_20200414_154223.jpg.6aead269116d5cc5c18af8df2d176e45.jpg

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That looks sound. Hate to say it but it does look like the regulator will have to come off. How well can you see the brushes where they contact the slip ring? That's usually the problem with these. 

Cleaning. Jizer, gunk or similar followed with hot soapy water. Unless you have a can of brake cleaner or similar.

Edited by Sir Nibble
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But don’t forget that with a 14v regulator the alternator output current will be nil if the battery voltage is above 14v because of the solar panel.  Even if the solar floats at 13.5v, with a fully charged battery the alternator output will not be much to push the battery up to 14v.  So alternator current measurements may be a bit unexpected without some significant load on your electrical system and possibly cover the solar panels as well to stop the solar doing too much work when testing.

Edited by Chewbacka
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32 minutes ago, Sir Nibble said:

How well can you see the brushes where they contact the slip ring? That's usually the problem with these. 

Er... I don't know what any of those things are, so I am guessing I can't see them at all. I'll get WD40ing that nut thats stripping and hopefully I'll be able to get it off and see what's going on. However the timing - a day after I installed solar and was mucking about with the alternator wiring - seems to suggest this isn't just something that's "gone" but that it's something I've caused.

 

7 minutes ago, Chewbacka said:

with a 14v regulator the alternator output current will be nil if the battery voltage is above 14v because of the solar panel.  Even if the solar floats at 13.5v, with a fully charged battery the alternator output will not be much to push the battery up to 14v.

Yeah, with my engine off my voltage meter is registering 13.9V and the BMV is registering 13.96V. The MPPT is registering 13.98V on the battery and 2.4A of current (Float state). So that does suggest to me that the solar has raised the system voltage too high and so the alternator won't kick in.

 

I'll try run the engine after dark and see what happens. If it is the solar, I believe I can turn down the charge voltage so that the alternator can still charge - it seems a bit rubbish to not be able to charge the battery while I'm cruising just because it's a sunny day.

 

Is it possible also that my 110Ah battery is also just "full"? The BMV says 81% SoC but I have no idea how it could possibly know that. I think that most of my load during the day is met by the solar, but it says 23Ah used since last full charge.
 

I'm sure that there is some wisdom in all these numbers but I've only just installed this device and I'm not sure how to read it yet.

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9 minutes ago, ivan&alice said:

Er... I don't know what any of those things are, so I am guessing I can't see them at all. I'll get WD40ing that nut thats stripping and hopefully I'll be able to get it off and see what's going on. However the timing - a day after I installed solar and was mucking about with the alternator wiring - seems to suggest this isn't just something that's "gone" but that it's something I've caused.

 

Yeah, with my engine off my voltage meter is registering 13.9V and the BMV is registering 13.96V. The MPPT is registering 13.98V on the battery and 2.4A of current (Float state). So that does suggest to me that the solar has raised the system voltage too high and so the alternator won't kick in.

 

I'll try run the engine after dark and see what happens. If it is the solar, I believe I can turn down the charge voltage so that the alternator can still charge - it seems a bit rubbish to not be able to charge the battery while I'm cruising just because it's a sunny day.

 

Is it possible also that my 110Ah battery is also just "full"? The BMV says 81% SoC but I have no idea how it could possibly know that. I think that most of my load during the day is met by the solar, but it says 23Ah used since last full charge.
 

I'm sure that there is some wisdom in all these numbers but I've only just installed this device and I'm not sure how to read it yet.

On a sunny day and cruising the battery WILL charge until it is full, at which point it will stop charging.  As to wether the charge current comes from the solar or alternator makes not a jot of difference to the battery.  The thing to remember is a full battery is a happy battery, and it does not care where it’s charge current comes from - so long as you don’t over charge it.

 

You could actually argue it is better coming from the solar as it will reduce the work done by the alternator reducing wear. 

 

Turning down the solar charging voltage is a bad idea, as when you are not cruising the solar will still have a low voltage set and so will only charge very slowly, which is NOT what you want.

 

In my case on a bright sunny day my batteries are charged by about lunch time.

Edited by Chewbacka
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I have an ammeter on my alternator output and solar panels, if I do not go cruising until after lunch on sunny day the batteries are already full from solar, therefore my alternator ammeter reads zero and my solar controller reads 5Amps tail current rising to 8Amps when the fridge cycles on. If I then pass through a shaded region, the solar ammeter reads less and the alternator ammeter rises above zero. You can only fill your batteries the once (as long as your voltage settings are correct of course).

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46 minutes ago, ivan&alice said:

Er... I don't know what any of those things are, so I am guessing I can't see them at all. I'll get WD40ing that nut thats stripping and hopefully I'll be able to get it off and see what's going on. However the timing - a day after I installed solar and was mucking about with the alternator wiring - seems to suggest this isn't just something that's "gone" but that it's something I've caused.

 

Yeah, with my engine off my voltage meter is registering 13.9V and the BMV is registering 13.96V. The MPPT is registering 13.98V on the battery and 2.4A of current (Float state). So that does suggest to me that the solar has raised the system voltage too high and so the alternator won't kick in.

 

I'll try run the engine after dark and see what happens. If it is the solar, I believe I can turn down the charge voltage so that the alternator can still charge - it seems a bit rubbish to not be able to charge the battery while I'm cruising just because it's a sunny day.

 

Is it possible also that my 110Ah battery is also just "full"? The BMV says 81% SoC but I have no idea how it could possibly know that. I think that most of my load during the day is met by the solar, but it says 23Ah used since last full charge.
 

I'm sure that there is some wisdom in all these numbers but I've only just installed this device and I'm not sure how to read it yet.

Is your battery full? Ignore the SoC on the BMV. The 23Ah could be ok to look at IF you synchronised it to full in the last few days. If you havent then ignore that as well. With only 110Ahr capacity you must have got to full today with all the sun we have had....but how much did you take out of the 110Ahr battery last night? At midday, what Amps were the panels putting in? If it was up in the 20A region you should be fairly well full but did the MPPT go to float too early. You really need to map out all these things before trying to fix the alternator......or cover up the panels and see what the alternator is doing without them.

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1 hour ago, Chewbacka said:

On a sunny day and cruising the battery WILL charge until it is full, at which point it will stop charging.  As to wether the charge current comes from the solar or alternator makes not a jot of difference to the battery.  

Except the current from my alternator (which I've measured at 50A on a flat battery and all my domestic loads on) is a lot more than what I'll get out of the solar?

 

So wouldn't I want to use the alternator current when charging, if I can? Not to mention that I'm running loads during the day and need the power.

 

 

46 minutes ago, Dr Bob said:

Ignore the SoC on the BMV. The 23Ah could be ok to look at IF you synchronised it to full in the last few days. If you havent then ignore that as well.

No I haven't synchronised to full, I was planning to do that after my next long cruise so that I could be sure the battery was full. I know that the last 10% or so of the battery take many hours to charge to full.

 

46 minutes ago, Dr Bob said:

With only 110Ahr capacity you must have got to full today with all the sun we have had....but how much did you take out of the 110Ahr battery last night?

Barely anything - a few LED lights for maybe 2 hours and my freshwater pump cycling around 3-4 litres. It was very sunny yesterday - MPPT reports a 940Wh yield (only 560Wh today).

 

48 minutes ago, Dr Bob said:

At midday, what Amps were the panels putting in? If it was up in the 20A region you should be fairly well full

I didn't check this but it says P max of 111W, which suggests around 9A max current (if I'm reading this right?). Unfortunately the BMV doesn't seem to record the history on the device - I think I should install a rasp pi to permanently connect to it and log all this data so I can answer these questions more easily. I'll check tomorrow at midday what the current says.

 

52 minutes ago, Dr Bob said:

did the MPPT go to float too early

I have left it on the default charge setting (Gel Victron deep discharge, Gel Exide A200, AGM...) Apsorption 14.4V, Float 13.8V, Equalisation 16.2V. My battery type is not one of the default options and I haven't found out the correct numbers to use yet (I have a sealed lead acid (lead calcium) dual purpose domestic battery). So I'm afraid I can't answer this question yet, either.

 

 

It's 19:10 here and the sun is quite low so I thought I'd do a quick test.

 

The MPPT is showing "Bulk" and ~8W coming in.

 

The BMV is showing a voltage of 12.92V with no domestic load on right now (base drain is -0.4A).

 

I started the engine and measured the amp output of the alternator with my clamp meter - it jumped to 25A or so soon after starting, but then quickly (over 15 seconds or so) started reducing until it was at 6 or 7A. The voltage of the system is unchanged.

 

I'll try again in an hour when it's properly dark.

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Just now, ivan&alice said:

I'll try again in an hour when it's properly dark.

 

My money is on there being nothing wrong with your alternator, as I suggested in Post 100! 

 

Make sure the battery isn't 101% charged before you try tonight after dark, or at least bung some hefty load on it, like running the water pump and shower drain pump while you check to see what alternator output current you get.

 

 

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12 minutes ago, Mike the Boilerman said:

 

My money is on there being nothing wrong with your alternator, as I suggested in Post 100! 

 

Make sure the battery isn't 101% charged before you try tonight after dark, or at least bung some hefty load on it, like running the water pump and shower drain pump while you check to see what alternator output current you get.

 

 

A good load is a hair drier if you have one and a big alternator, but not for too long.........

 

added - The alternator and solar will happily work together, the battery decides how much current it will take, so though your alternator can put out 50A, the battery if fully charged will only take a couple of amps, that is all the battery wand.  The solar is not preventing the alternator doing it’s  job, it is just that at low charging currents it will do most of the work because it’s voltage is slightly higher, increase the electrical load and the battery voltage will drop and the alternator will then start working to keep the voltage at 14v if it can.

Edited by Chewbacka
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2 minutes ago, Mike the Boilerman said:

My money is on there being nothing wrong with your alternator, as I suggested in Post 100! 

 

Make sure the battery isn't 101% charged before you try tonight after dark, or at least bung some hefty load on it, like running the water pump and shower drain pump while you check to see what alternator output current you get.

The thing I don't understand is, even if the battery is full (like after a long cruise) when running the engine, I'd still see 14.2ish volts. So it doesn't make sense to me that it can be 12.9ish.

 

I loaded up the battery so that it will be a bit depleted when I try again later, and I'm now getting three different voltages on the system.

 

11.5V on my old voltmeter, 11.94V on my MPPT, 12.19V on my BMV and on my Uni-T. I trust the last voltage the most since that's taken directly at the battery, so I'm going to keep going with the experiment despite the fact that 11.x volts would normally send me into a panic!

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Sun is down, battery drained of at least 10Ah and I tried the above experiment again. Voltage was down to around 11.8V when under load after running down the battery for 30 mins. Same result - jumped up to 20A for a few seconds, then counted down to 6A. Voltage of the system is still around 12V, even with the engine running. The alternator would always cause the voltage to rise to over 14V in the past no matter what state of charge the battery was at.

 

Is it possible that simply having the MPPT in circuit with the alternator is affecting the voltage?

 

I notice the starter battery is at 14.65V which suggests that it's being charged (when I turn off the engine it dropped to 13.9V). Is it possible that it's a problem with my VSR / split charge relay - so that the alternator is charging the start battery and not the domestic?

 

I wired the solar controller to the positive of the domestic, effectively avoiding the VSR. Could that be the problem?

Edited by ivan&alice
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1 hour ago, ivan&alice said:

Sun is down, battery drained of at least 10Ah and I tried the above experiment again. Voltage was down to around 11.8V when under load after running down the battery for 30 mins. Same result - jumped up to 20A for a few seconds, then counted down to 6A. Voltage of the system is still around 12V, even with the engine running. The alternator would always cause the voltage to rise to over 14V in the past no matter what state of charge the battery was at.

 

Is it possible that simply having the MPPT in circuit with the alternator is affecting the voltage?

 

I notice the starter battery is at 14.65V which suggests that it's being charged (when I turn off the engine it dropped to 13.9V). Is it possible that it's a problem with my VSR / split charge relay - so that the alternator is charging the start battery and not the domestic?

 

I wired the solar controller to the positive of the domestic, effectively avoiding the VSR. Could that be the problem?

If the starter battery is 14.65V then that really sounds like the alternator is charging the start battery.

I know nothing about split charge relays but it certainly sounds like the problem may lie there. Someone clever will be along soon.

Can you just wire the main output of the alternator to the domestic bank not via the relay and run the engine to see if you get 14.4V on the domestic bank?

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Thanks Bob, yes I can do that. I will attempt this tomorrow. If I do get 14+V on my domestic, then I'll have to rethink how best to wire up these batteries. Seems to me the starter is charged quickly and easily so the only thing the VSR is for really is to prevent domestic loads being drawn from the starter. Perhaps the best solution is a completely separate system for the starter that is charged by the small alternator. I'm actually not sure at all what role if any that small alternator is playing in my system right now.

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4 minutes ago, ivan&alice said:

Thanks Bob, yes I can do that. I will attempt this tomorrow. If I do get 14+V on my domestic, then I'll have to rethink how best to wire up these batteries. Seems to me the starter is charged quickly and easily so the only thing the VSR is for really is to prevent domestic loads being drawn from the starter. Perhaps the best solution is a completely separate system for the starter that is charged by the small alternator. I'm actually not sure at all what role if any that small alternator is playing in my system right now.

@Tony Brooks always recommends that you fit the VSR the other way round if you are using one, so it feeds the heavy loads to domestics first then charges starter when the voltage rises a bit, purely to avoid burning out the relay.

 

As you have two alternators, I'd say use them.  Poxy little alternator to starter battery, big beefy alternator to domestic bank, stick the VSR in the spares box.

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4 minutes ago, TheBiscuits said:

 

 

As you have two alternators, I'd say use them.  Poxy little alternator to starter battery, big beefy alternator to domestic bank, stick the VSR in the spares box.

Isnt that the way they are meant to be wired? Mine are.

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5 minutes ago, TheBiscuits said:

@Tony Brooks always recommends that you fit the VSR the other way round if you are using one, so it feeds the heavy loads to domestics first then charges starter when the voltage rises a bit, purely to avoid burning out the relay.

 

As you have two alternators, I'd say use them.  Poxy little alternator to starter battery, big beefy alternator to domestic bank, stick the VSR in the spares box.

Or maybe the bin, if the VSR has indeed burned out. Someone earlier in this thread suggested connecting both alternators to the battery bank so that I could make use of charge from both of them. Indeed that might actually be the current setup. The small alternator wires just enter a rats nest and I'm not completely sure where they come out of if indeed the small alternator is even working. I will need to spend time mapping out all the electrics and testing everything. Then I'll be able to make some informed decisions about what to change. But using the two alternators as intended seems like the most robust and least complex system.

 

I should note that I'm in the process of upgrading to a lithium bank. I'm waiting for my batteries to become available. I intend for the alternator to not form a part of the lithium system at first, until I am certain I know what I'm doing. But when I get around to including the alternator in charging the lithiums I think being able to deal with the starter as a completely separate system might simplify things a lot.

 

2 minutes ago, Dr Bob said:

Isnt that the way they are meant to be wired? Mine are.

Am I thinking of someone else - haven't you connected your lithiums to allow starting from lithium if you need to?

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16 minutes ago, ivan&alice said:

Or maybe the bin, if the VSR has indeed burned out. Someone earlier in this thread suggested connecting both alternators to the battery bank so that I could make use of charge from both of them. Indeed that might actually be the current setup. The small alternator wires just enter a rats nest and I'm not completely sure where they come out of if indeed the small alternator is even working. I will need to spend time mapping out all the electrics and testing everything. Then I'll be able to make some informed decisions about what to change. But using the two alternators as intended seems like the most robust and least complex system.

 

I should note that I'm in the process of upgrading to a lithium bank. I'm waiting for my batteries to become available. I intend for the alternator to not form a part of the lithium system at first, until I am certain I know what I'm doing. But when I get around to including the alternator in charging the lithiums I think being able to deal with the starter as a completely separate system might simplify things a lot.

 

Am I thinking of someone else - haven't you connected your lithiums to allow starting from lithium if you need to?

No not me. Starter circuit only on the starter lead acid. I have a long pair of jump leads just in case.

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Problem solved! Embarassed to report back, but I must do my duty!

 

Nothing wrong with alternator - that was a red herring. I connected the alternator to the domestic instead of the starter as Bob suggested in Post 116, and the voltage jumped up to 14.7 when I started the engine.

 

That settles it thinks I - must be a problem with the VSR. So I take my spanner to it, and what do I discover but the negative (voltage sensing wire) of the VSR is disconnected from my starter battery. D'oh.

 

Put everything back where it was and it's all working as it should be. So my hunch that the solar install caused the problem was correct, but it was operator error - when I connected the BMV shunt to the negative terminal, I must have popped off the negative from the BMV and dropped it behind the starter battey where it wasn't visible.

 

Sorry for taking everyone's time but at least I learned a lot about how alternators work, which will certainly help when I get around to figuring out how to regulate the voltage of the alternator to prevent overcharging my lithiums. Thanks again for the advice. I'll leave the alternator and VSR in place for now, and I'll reconsider how I'm wiring up my alternators when I get my batteries.

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On 16/04/2020 at 19:37, ivan&alice said:

Put everything back where it was...

Do you now have the alternator feeding the domestics with the VSR sensed off them, as opposed to feeding the starter battery first?

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