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[leboutillier]

Hi all my name is Scott I am after a bit of your knowledge if you could 

 

I have a alternator on my mother's boat that i have had to change due to only giving out 7 volts to the leisure/domestic batterys and it has a additional green wire on it but my replacement does not I have included a image if that helps 

I know B+ is battery positive and D+ goes to the warning lamp

 

However on the other the alternator that goes to the starter battery it has the same wire in the same place 

Bothe of the original alternators was connected to gether at the green wire 

 

If I disconnected the green wire the tacho/Reves stop working and the red warning light will go out but if I conect it up the red warning light will come on and the tacho will work again 

 

Both Alternators are working and giving out 14.5 volts to there relative battery's 

 

I'm just trying to work out the purpose of the green wire and is there a way to sort out the warning lamp but still keep the tacho working. 

 

It is a lucas type a127 alternator 

[BEngo]

The normal reason for an extra wire  where you show it is as the field control wire for an alternator booster by Stirling, x-alt and others.  aka "battery boiler" which raises the alternator output voltage to about 14.5 V

However, since the green wire also affects the warning light I suspect there has been some modification  of the feed to the regulator.  Undo the three screws that hold the regulator on and remove it. It it is the ribbed thing on the left of your pic.  As built there is a yellow wire from the inside of the alternator to a push fit spade terminal in the regulator.  This provides the power to the regulator and the field coils.  I guess someone has decided to power the regulator independently of the alternators internal diodes.

 

The rev counter should normally be fed from the W terminal.

The warning light is normally connected to the D terminal.

 

N

 

[leboutillier]

Thanks Bengo

The picture I originally put on is jus a generic one edited hear is the actual one  the red bit is the connecter 

Edited October 17, 2023 by leboutillier

[Tony Brooks]

Almost certainly as Bengo explained, except it sounds to me yor description of the original wiring is either a misunderstanding or something weird. With certain advanced alternator controllers, you can mod the alternator to bypass its own regulator and leave the new "advanced" one to do the total controlling. In this case, disconnecting the extra wire will shut the alternator down and the rev counter will stop working & the red light come on.

 

My guess is that the wires from both alternators link on or close to a controller.

[leboutillier]

The red light is on when connected but will go out when disconnected I'm going to look in to it at the weekend for now as bothe are charging at around 13 to 14 volts I will jus use it as a engin running light un till I can get to the back of the control panel 

[BEngo]

Take the regulator off the old one and post a pic of the inside parts of it please. I am particularly interested in where the wire is connected to, so as to work out what it does.

 

In the short term you could fit the old regulator to the new alternator and see what effect that has when connected as original.  If it produces  7 V the regulator is broke!  In that case a new regulator ( v cheap) would leave you with a spare used alternator.

 

In the mean 5ime both alternators are charging at a sensible voltage so there is no urgency.

 

N

[Tony Brooks]

1 hour ago, BEngo said:

Take the regulator off the old one and post a pic of the inside parts of it please. I am particularly interested in where the wire is connected to, so as to work out what it does.

 

In the short term you could fit the old regulator to the new alternator and see what effect that has when connected as original.  If it produces  7 V the regulator is broke!  In that case a new regulator ( v cheap) would leave you with a spare used alternator.

 

In the mean 5ime both alternators are charging at a sensible voltage so there is no urgency.

 

N

 

To add:

 

When the OP takes the regulator off it is important to tell us where the (normally) yellow wire with a 6mm female blade connection on it is connected and if it seems to have been modified.

[leboutillier]

So the regulator had gone down it has now been repaired and installed back on to the engin the red light is still on but verry dim now 

I think you was right about the booster as you previously mentioned 

I am going to have a look for a relay when I'm next down as I suspect it might be either sticking or have carbon on the contact 

I didn't have a chance to take the regulator off as my brother had it repaired in Leicester 

We are going to keep the new on as a spare and I will carry out the modification to it when next up aswell 

 

Thanks for all the input

[Tony Brooks]

 

You were asked for two specific questions, Bengo's about a photo and mine about the yellow cable, yet you seem to ignore that and decide the regulator has failed. We still need to know the purpose of linking tho fly leads on both alternators.

 

A127 alternators do not use relays, although with a twin alternator set up the warning lamp circuit may use a relay to power the second alternator's warning lamp. Once the alternator is charging, then that relay plays no part in the charging. However, if there is for any reason a different voltage on either side of the warning lamp, the lamp will light or glow. This voltage difference when the alternator is charging is USUALLY caused by one or more field diodes in the alternator, but less commonly by dirty contacts in the ignition switch or resistance between the battery and ignition switch. If the boat does have a relay powering the second warning lamp then, as you suggests, resistive contact MIGHT be the cause of the lamp glowing, but such faults are far from common.

 

Not sure if this helps.

[Tracy D'arth]

I am not sure what connecting both the field brush extra wires together will have, I have never done it with an external alternator controller.

I must ask Sterling next time I am talking to them.

[leboutillier]

I had not ignored the questions I was unable to answer due to no having the alternator with me during the time of them being asked my brother had taken it for diagnosis and repairs 

I am sorry for any confusion that it has caused 

[Tony Brooks]

2 minutes ago, Tracy D'arth said:

I am not sure what connecting both the field brush extra wires together will have, I have never done it with an external alternator controller.

I must ask Sterling next time I am talking to them.

 

If it is a straight link with no advanced controller, then I suppose it would allow on regulator to control two alternators, providing the regulator can handle the extra current long term. I can see this MIGHT be seen as an advantage in the case or a relay being used to parallel the two alternators.

 

If both connect to a single advanced controller (not what the OP said) then, as long as the controller can handle the extra current, it saves buying two controllers.

Just now, leboutillier said:

I had not ignored the questions I was unable to answer due to no having the alternator with me during the time of them being asked my brother had taken it for diagnosis and repairs 

I am sorry for any confusion that it has caused 

 

Fair enough, but unless we can form a model of what you have in our minds, we really can't help much. The way you described the wiring seems exceptionally weird and non-standard, so the typical models will not work.

[leboutillier]

One of the reasons that I thought it may be a relay I because I have a old vw with a split charge system installed and have had a problem in the past around 12 years ago 

 

As a hgv mechanic I like the fact that the ecu can control it now but it is more expensive way when things go wrong 

 

As I was call upon yesterday to carry out a fix and the loss of light at around 5:30 I was unable to dig to deep especially with 2 dogs trying to look aswell 😆 

 

But again thanks for the information you have supplied as it has given me mor of a insite of what I have to look at 

 

It has been mentioned that the diode could be causing a back flow of current on the engin battery altnater and in tern was the caus of the lamp being on and now that they are both connected it is the reason that it is verry dim barley notable 

[Tony Brooks]

27 minutes ago, leboutillier said:

One of the reasons that I thought it may be a relay I because I have a old vw with a split charge system installed and have had a problem in the past around 12 years ago 

 

As a hgv mechanic I like the fact that the ecu can control it now but it is more expensive way when things go wrong 

 

As I was call upon yesterday to carry out a fix and the loss of light at around 5:30 I was unable to dig to deep especially with 2 dogs trying to look aswell 😆 

 

But again thanks for the information you have supplied as it has given me mor of a insite of what I have to look at 

 

It has been mentioned that the diode could be causing a back flow of current on the engin battery altnater and in tern was the caus of the lamp being on and now that they are both connected it is the reason that it is verry dim barley notable 

 

Just to make sure that you are aware that an alternator with a blown main diode or a phase that has failed for other reasons will still appear to charge the batteries. However, the maximum output current will be low and the regulated voltage is also likely to be a little low. So check the current will well discharge batteries and the engine revving and the voltage with the engine revving but less than 10 amps charging flow.

 

Whoever tested the regulator should have tested the outputs, but one can never be sure.

[leboutillier]

So I managed to get back to the boat to day and have the wiring diagram as it should be as it is using a ADVERC battery management system I can now see some problems 

The boat is a single beta marine with 2 alternators my querie now is 

Altnator 1 supply's the engin battery as far as I am aware and alternator 2 supplies the domestic batterys 

But what I don't understand is why the adverc bcm is connected to alternator 1 or does it not matter as both alternators first go to the SPLIT CHARGE DIODE: ( Multi-Battery Isolator)

Also would this diagram still be the same with one engin and 2 alternators 

 

Sorry to keep asking I am just trying understand the system and clean up the 30 year old wiring 

Also the previous owner did not have separate red charg lights or a yellow warning light 

[ditchcrawler]

The Adverc is connecting to both alternators, as it loops the field wire from the left hand one to the right hand one so raising the voltage of both alternators at the same time . B+ are also linked to take care of over voltage. The Adverc is only sensing the voltage from the domestic bank of batteries.
Is this how your boat is actually wired or have you just found the Adverc drawing on how to connect two alternators?

Edited October 21, 2023 by ditchcrawler

[leboutillier]

As far as I can tell the b+ is going to 1 split charge diode and the other is going to the other as you can see they need a good clean 

The battery monitor only read a maximum of 13.4 v charging at 14.4 amp's after the engin was running for 10 minutes I am assuming that it went into trickle charge mode 

But even after 2 hours the batterys red that they was only 80% full after ther settling period 

[ditchcrawler]

50 minutes ago, leboutillier said:

As far as I can tell the b+ is going to 1 split charge diode and the other is going to the other as you can see they need a good clean 

The battery monitor only read a maximum of 13.4 v charging at 14.4 amp's after the engin was running for 10 minutes I am assuming that it went into trickle charge mode 

But even after 2 hours the batterys red that they was only 80% full after ther settling period 

 

[Tony Brooks]

The whole thing looks horribly complicated for a single engine twin alternation boat.

 

In general passive split charge diodes are bad news because they will drop up to about 0.6 volts across the diode so to retain a decent charge the Adverc was fitted so it boosts the charging voltage by whatever the volt drop across the diodes is. Active electronic "diodes" waste less voltage in this respect.

 

The diagram you supplied seems to show a very non-typical way of using the diodes. They seem to be combining both alternators to charge both battery banks. Nowadays, this can be done far cheaper and made far simpler by the use of a single VSR (voltage sensitive relay). B+ to their respective battery positives and then the VSR between the  two banks B+. Use a bi-directional VSR and it will also feed any future solar to both banks as well.

 

Alternators made over the last 20 years or so tend to have the regulated voltage set to between 14.4 and 14.7 so an Adverc gives only a minor advantage, in my view simplifying the system with a VSR and ditching the Adverc will make minimal difference to the charging.

 

As far as the % state of charge goes, it is almost certainly a lie. Those monitors have encouraged many new boaters to destroy their batteries in double quick time by lying so the batteries are never fully charged. Please use rested voltage to assess the state of charge and current flow to know when charging can be stopped. Remember that with lead acid batteries it take many hours to fully charge them. It can easily be 10 hours plus for a well discharged bank. PLEASE READ, UNDERSTAND, AND ACT ON THE BATTERY MONITOR INSTRUCTIONS, and set the tail current to no more than 2% of the actual battery capacity. It will less than the label says.

 

I hope this helps.

 

[Tracy D'arth]

The BMS is lying, they do.

As Tony says you charge longer till the current going in to the batteries is less than 2% of the rated battery capacity.

So If you have 3 off  110Ah batteries as leisure/cabin battery you charge until the current going in falls below 6.6A.  Switch off and let the batteries stand with no load for at least an hour or two. Use a multimeter and check the voltage. They should then be at 12.7V or slightly better.

If not they are toast.

[Tony Brooks]

5 minutes ago, Tracy D'arth said:

The BMS is lying, they do.

As Tony says you charge longer till the current going in to the batteries is less than 2% of the rated battery capacity.

So If you have 3 off  110Ah batteries as leisure/cabin battery you charge until the current going in falls below 6.6A.  Switch off and let the batteries stand with no load for at least an hour or two. Use a multimeter and check the voltage. They should then be at 12.7V or slightly better.

If not they are toast.

 

All true, but in this specific case I think he needs to add the start battery capacity to get the total being charged.