Alternator connection

[VicS]

I have checked and rechecked BM-! connections, ....

As to the positive circuits to the selector switch, both BATT1 & 2 & BOTH are fed from a small busbar fed directly from the alternator output. Simple selection of the swiches send current either to BATT1, ie domestic, or BATT2 to starter motor, .....
I have noticed, and this may be significant, when I start the engine just with BATT 2 as normal, the charge shown on the engine meter is very little, as the engine battery is pretty much always well charged, which also matches the BM-1 reading to, when I then select BATT1 and deselect BATT2 the engine meter reads much higher as does the BM-1, but the difference seems greater.

So the positive connections are just the simplest possible arrangement for wiring two batteries using a 1, 2, both, off switch. ( you will now be given a 1001 reasons why you should change it and 10001 suggestions as to how you should change it but no matter)

With batt 2 ( the start battery) selected you should see a significant charge current on the engine ammeter as soon as the engine starts but it should fall away as the starter battery recharges. You should not see any current, charge or discharge, registered on the BM1 while only the starter battery is selected except for any input from the solar panel.

When you switch to battery 1 you might see a charge current on the engine ammeter if the battery is not fully charged already but it should fall away as battery 1 recharges. The BM1 should show the same current plus any input from the solar panel, assuming there are no loads on the system.

When you stop the engine and switch the "ignition" off the engine panel ammeter should read zero and the BM1 should show the net current from any load battery 1 is supplying and any input from the solar panel.

If you observe anything different from the above then either things are not wired as you think or the engine panel meter is reading incorrectly.

I have assumed that the solar panel is connected to the house battery positive and the common negative bus bar... That is what I understand you to have said.

 

[Sarnia]

So the positive connections are just the simplest possible arrangement for wiring two batteries using a 1, 2, both, off switch. ( you will now be given a 1001 reasons why you should change it and 10001 suggestions as to how you should change it but no matter)

With batt 2 ( the start battery) selected you should see a significant charge current on the engine ammeter as soon as the engine starts but it should fall away as the starter battery recharges. You should not see any current, charge or discharge, registered on the BM1 while only the starter battery is selected except for any input from the solar panel.

When you switch to battery 1 you might see a charge current on the engine ammeter if the battery is not fully charged already but it should fall away as battery 1 recharges. The BM1 should show the same current plus any input from the solar panel, assuming there are no loads on the system.

When you stop the engine and switch the "ignition" off the engine panel ammeter should read zero and the BM1 should show the net current from any load battery 1 is supplying and any input from the solar panel.

If you observe anything different from the above then either things are not wired as you think or the engine panel meter is reading incorrectly.

I have assumed that the solar panel is connected to the house battery positive and the common negative bus bar... That is what I understand you to have said.

Yes they are the simplest connections, the PO was a marine engineer who, like me believes in the KISS principle, I have from time to time spoken to companies at boat shows who sell more complicated control systems, who viewed me, following my explanation of my system, as someone not quite right (they may have a point) and with evangelical furvor tried to convince me of the 1001 value reasons you refer to. I remain unconvinced, the simple system has worked well for me as I follow a routine to ensure it does.

Your observations as to what should happen do happen, when starting with BATT2 the engine ammeter momentarily swings high but immediatly returns to a low reading, as I keep the starter battery well charged. The BM-1 shows nothing other than what the solars produce or at night zero.
When I switch to BATT1 and switch off BATT2 both the engine ammeter and BM_1 show the charge, but as per my original question, are different, the engine ammeter is a basic one, and of unknown age, certainly some 10 years plus.
When stopping the engine and ignition to off, the BM-1 quickly reduces the charge shown down to whatever the solar are producing.
Yes the solar are connected to the house and the negative side of the shunt, farthest away from the battery which in turn is connected to to the common negative busbar.
I have made a drawing of the connections but cannot master the method to post her, i have sent you a PM.

 

[Sarnia]

I have now fitted the new 90 aml alternator, a few differences from the previous, when switch on and startthe the ignition light flashes briefly, the alternator comes 'online' immediatly, prevoiusly had to go to 1500 revs to do that.
The readings are the same, that is the BM-I shows 14/15 amps, the engine panel ammeter hits the stop at 50 amps and stays there.
After running for 30 mins the battery (domestic reading on BM-1) condition went from 40% to 72%, previously had taken longer to do that, which suggests to me the battery is getting more than what the BM-1 says it is. The battery condition in % takes a few minutes to settle after charging stops.
The new alternator unlike the previous is not grounded automatically, and i have fitted an earth to the negative in the same way the previous one was.
To see if moving the earth to the shunt, farthest away point, would make a difference but it didnt, as connectiong an earth as i have already is much the same thing.
Must be something I am missing somewhere.

 

[VicS]

I have now fitted the new 90 aml alternator, a few differences from the previous, when switch on and startthe the ignition light flashes briefly, the alternator comes 'online' immediatly, prevoiusly had to go to 1500 revs to do that.
The readings are the same, that is the BM-I shows 14/15 amps, the engine panel ammeter hits the stop at 50 amps and stays there.

Must be something I am missing somewhere.

If you started the engine on the start battery ( not on both) you should not see any reading on the BM1....... FSD on the engine ammeter (I think you said it's only 50A) with the new high output alternator is perhaps to be expected

You should not see any reading on the BM1 until the house battery is switched into service !

 

[VicS]

Hi Vic,
Thank you for taking the time to help.
I have attached the sketch of my battery connections and the BM-1.
Earlier today I fitted the new alternator, and I have posted the
results on YBW on our thread.

As you will see on the sketch the shunt is in the negative loop from
the domstic to the busbar, also linked to the starter battery negative
along the way.

Looking forward to hearing from you.

Mike

Here, hopefully, is the picture you sent by email

That does not appear to be correct

Wire the two batteries that form the house battery bank together in parallel then wire the pair, as though they were a single battery, as indicated in my diagram

You appear to have one end of the battery monitor shunt connected to only one of the pair of batteries. The connection to the other battery bypasses the shunt


Can you also produce diagram that shows how the positives are connected to the selector switch, how the solar panel is connected, and how the starter and alternator output are connected

 

[Sarnia]

If you started the engine on the start battery ( not on both) you should not see any reading on the BM1....... FSD on the engine ammeter (I think you said it's only 50A) with the new high output alternator is perhaps to be expected

You should not see any reading on the BM1 until the house battery is switched into service !

Correct, I do not see a reading until I switch to domestic from starter, the engine ammeter is also low until I do.
The ammeter has a max of 50amps, it hits it soon as switched to domestic, then after a while comes down a little, but is showing much more than the BM-1

 

[Sarnia]

Here, hopefully, is the picture you sent by email

That does not appear to be correct

Wire the two batteries that form the house battery bank together in parallel then wire the pair, as though they were a single battery, as indicated in my diagram

You appear to have one end of the battery monitor shunt connected to only one of the pair of batteries. The connection to the other battery bypasses the shunt


Can you also produce diagram that shows how the positives are connected to the selector switch, how the solar panel is connected, and how the starter and alternator output are connected

I see what you are saying about the negative on the second battery, I presumed it was parralling with the other via the shunt and then to the negative of the starter battery to the negative busbar.
On the sketch the neagtives of the first battery, the starter battery, and the return from the shunt are all connected, (as you can see in the middle or I would have shown a crossover) before going to the negative busbar.
I will make the changes you suggest, and try to get a sketch to you of the other wiring.

 

[Chris_Robb]

Thank you, yes i have after some searching found a replacement with dimensions that will fit my set up, I made a scale drawing to compare with spec sheets of various Pretolite models.

what belt size are you using to power the new 90amp alternator? The standard would probably be 9mm. I installed this alternator, and Adverc supplied a 13mm pulley on the alternator. I installed it with the original 9mm belts. When the batteries were low, the alternator belt slipped like hell and once filled the boat with black smoke!

I rang Adverc (lovely people) and they said - why do you think we fitted as 13mm pulley? Ah..... I changed the belt for the 13mm belt size - even though the other pulleys run proud as they are 9mm. Problem solved - don't even get black belt dust anymore.

If you change pulley radius, then your rev counter will not read correctly as they are run by a pulse from the alternator. Some rev counters can be adjusted.

 

[VicS]

I see what you are saying about the negative on the second battery, I presumed it was parralling with the other via the shunt and then to the negative of the starter battery to the negative busbar.

The way it is connected results in the battery monitor measuring the current to and from only the right hand one of the pair of batteries

 

[nigelmercier]

On the sketch the neagtives of the first battery, the starter battery, and the return from the shunt are all connected, (as you can see in the middle or I would have shown a crossover)...

FYI, this type of connection drawing is deprecated. If the wires join, you should accentuate this with a dot. You can continue to use loop-overs as well if you prefer.

As I said in an earlier post, treat the domestic batteries and shunt as a single unit. Nothing else should be connected to the negative terminals, which should be joined locally. In your diagram, the shunt is bypassed, as Vic says. Remove the wire that joins the left battery to the negative bus, and connect to the other battery.

 

[Sarnia]

what belt size are you using to power the new 90amp alternator? The standard would probably be 9mm. I installed this alternator, and Adverc supplied a 13mm pulley on the alternator. I installed it with the original 9mm belts. When the batteries were low, the alternator belt slipped like hell and once filled the boat with black smoke!

I rang Adverc (lovely people) and they said - why do you think we fitted as 13mm pulley? Ah..... I changed the belt for the 13mm belt size - even though the other pulleys run proud as they are 9mm. Problem solved - don't even get black belt dust anymore.

If you change pulley radius, then your rev counter will not read correctly as they are run by a pulse from the alternator. Some rev counters can be adjusted.

Thank you, yes the pulley is 13mm and fits perfectly.

 

[Sarnia]

FYI, this type of connection drawing is deprecated. If the wires join, you should accentuate this with a dot. You can continue to use loop-overs as well if you prefer.

As I said in an earlier post, treat the domestic batteries and shunt as a single unit. Nothing else should be connected to the negative terminals, which should be joined locally. In your diagram, the shunt is bypassed, as Vic says. Remove the wire that joins the left battery to the negative bus, and connect to the other battery.

I have had a 'damascus' moment, Vic is absolutley spot on, the shunt is in quite the wrong place, or rather wired into the wrong place.
His original sketch, and that from NASA show quite clearly the shunt must be between the battery and the Negative busbar.
My negative feed to the busbar has been from the first battery, the shunt must be between them, the diagram clearly shows it isnt, so a quick rewire, I have sent Vic the sketch he will post here.
The results are great, BM-1 now showing initial charge of 30 amps, (battery condition 40%) previosely only 14, the engine ammeter shows approx the same, maybe slightly higher, but as the batteries charge they level out muh the same.
A lesson learned, check the diagrams and do not assume, but without so much help I would be still struggling, thank you everyone who has posted in reply.

 

[Chris_Robb]

I have had a 'damascus' moment, Vic is absolutley spot on, the shunt is in quite the wrong place, or rather wired into the wrong place.
His original sketch, and that from NASA show quite clearly the shunt must be between the battery and the Negative busbar.
My negative feed to the busbar has been from the first battery, the shunt must be between them, the diagram clearly shows it isnt, so a quick rewire, I have sent Vic the sketch he will post here.
The results are great, BM-1 now showing initial charge of 30 amps, (battery condition 40%) previosely only 14, the engine ammeter shows approx the same, maybe slightly higher, but as the batteries charge they level out muh the same.
A lesson learned, check the diagrams and do not assume, but without so much help I would be still struggling, thank you everyone who has posted in reply.

Glad you solved that. So whilst you are at it, what voltages are you getting on the BM.

When I put my much larger alternator on (prestolite 110amp), I increased the wiring size from the alternator by doubling up the wires (I know - not strictly kosher) - there was a significant increase in AMPS from about 60 to 80 amps, (into 440 a/h bank) showing that the old wires were in fact overloaded.

 

[Sarnia]

Glad you solved that. So whilst you are at it, what voltages are you getting on the BM.

When I put my much larger alternator on (prestolite 110amp), I increased the wiring size from the alternator by doubling up the wires (I know - not strictly kosher) - there was a significant increase in AMPS from about 60 to 80 amps, (into 440 a/h bank) showing that the old wires were in fact overloaded.

I am showing when charging 13.8 or thereabouts, at the alternator I get 14.14/ 14.4 depending on when I measure it, by that I mean the state of charge at the time.
I intend to increase my bank from 380 to either about 560 or 600 depending if I add anothe 180, or a pair of 6v Trojan T140 which are 225.
I know the purists prefer a single new cable of increased size instead of doubling up, but something I will do if I need to rather than undo looms etc.
I see you are in Leros, I am currently in Vlhio Lefkada, leaving the boat here for the winter.

 

[Chris_Robb]

I am showing when charging 13.8 or thereabouts, at the alternator I get 14.14/ 14.4 depending on when I measure it, by that I mean the state of charge at the time.
I intend to increase my bank from 380 to either about 560 or 600 depending if I add anothe 180, or a pair of 6v Trojan T140 which are 225.
I know the purists prefer a single new cable of increased size instead of doubling up, but something I will do if I need to rather than undo looms etc.
I see you are in Leros, I am currently in Vlhio Lefkada, leaving the boat here for the winter.

Hi - are you afloat in Vliho for the winter? If so get all the windage off the boat you can as there are significant gusts through the bay.


Voltages: 13.8 at the battery is far too low and explains why you are getting less amps on charging than I would have expected for a reasonably discharged battery. I would have expected you to see at least 70 amps on the BM1 for a short time. You need to look at where/ how the voltage loss is happening. To do this you will need long cables to your multimeter with Croc clips and connect each end of the cable - 1 on the alternator and one on the battery - I think you will see .8 of a volt. Normally this would be due to a splitting diode loosing volts, but you have a 1,2 both switch(?) so you should not loose volts through that.

This loss of volts has a significant effect on the rate of charge on the batteries. you may well find that the connections and cables are getting warm.

Additional Batteries: It is perceived wisdom to try to match batteries as closely as possible in type, so I don't know the effect of mixing types especially 6 volt and 12V. However it is certainly worth increasing to as large a bank as possible as there are considerable benefits - not least, that your charge rate is effectively much faster as there is less resistance.

Good luck - see you afloat one day???

 

[VicS]

I have had a 'damascus' moment, Vic is absolutley spot on, the shunt is in quite the wrong place, or rather wired into the wrong place.
His original sketch, and that from NASA show quite clearly the shunt must be between the battery and the Negative busbar.
My negative feed to the busbar has been from the first battery, the shunt must be between them, the diagram clearly shows it isnt, so a quick rewire, I have sent Vic the sketch he will post here.
The results are great, BM-1 now showing initial charge of 30 amps, (battery condition 40%) previosely only 14, the engine ammeter shows approx the same, maybe slightly higher, but as the batteries charge they level out muh the same.
A lesson learned, check the diagrams and do not assume, but without so much help I would be still struggling, thank you everyone who has posted in reply.

My bb connection hs been down since Tuesday morning ..... service provider doing an upgrade that went tits-up .... only just back on line again .

Glad to read you've sorted your problems

 

[nigelmercier]

My bb connection hs been down since Tuesday morning ...

Nightmare! My niece is teaching in Uganda, they have been without water for a week, but they still have Internet.

 

[Sarnia]

Hi - are you afloat in Vliho for the winter? If so get all the windage off the boat you can as there are significant gusts through the bay.


Voltages: 13.8 at the battery is far too low and explains why you are getting less amps on charging than I would have expected for a reasonably discharged battery. I would have expected you to see at least 70 amps on the BM1 for a short time. You need to look at where/ how the voltage loss is happening. To do this you will need long cables to your multimeter with Croc clips and connect each end of the cable - 1 on the alternator and one on the battery - I think you will see .8 of a volt. Normally this would be due to a splitting diode loosing volts, but you have a 1,2 both switch(?) so you should not loose volts through that.

This loss of volts has a significant effect on the rate of charge on the batteries. you may well find that the connections and cables are getting warm.

Additional Batteries: It is perceived wisdom to try to match batteries as closely as possible in type, so I don't know the effect of mixing types especially 6 volt and 12V. However it is certainly worth increasing to as large a bank as possible as there are considerable benefits - not least, that your charge rate is effectively much faster as there is less resistance.

Good luck - see you afloat one day???

Also had pc problems, seems like an epidemic!.

Yes I am staying afloat here for the winter, preping the boat ready for as much as i can, have the Vlhio Club looking after her.

To be honest I did expect better than 28/30amps and 13.8v initially, have checked the alternator feed and it does get warm, it is about 10mm cable overall, I am doing some further checks today, the BATT1, 2 BOTH switches are older type, going to remove and see if they ok and also add another feed cable, not ideal but will certainly cure any resistance.

I am not quite sure what you meant about using long cables with croc clips, my alternator is close enough to do the reading you suggested.
Should I do it with the engine off, or when charging?

As to mixing batteries, we have discussed this at length in another thread, and the concensus is that so long as they are the same type of battery, ie: lead acid, then whether they are 2 x 6v in series or just 1 x 12v does not make any difference.

Getting on with the checks now.

 

[Sarnia]

My bb connection hs been down since Tuesday morning ..... service provider doing an upgrade that went tits-up .... only just back on line again .

Glad to read you've sorted your problems

Certainly have solved the shunt wiring, DEFINITLY correct now.
Would welcome your input to Chris_Robb's point re expectation of higher amps and volatage, the alternator feed is getting warm, not hot, just warm, and can feel the same at the + busbar that feeds the BATT1,1, 2 switches. Going to chech those out and run an extra cable, , managed to get some 70 amp stuff today.
Please keep any advice coming, same applies to nigel and others.

 

[VicS]

Certainly have solved the shunt wiring, DEFINITLY correct now.
Would welcome your input to Chris_Robb's point re expectation of higher amps and volatage, the alternator feed is getting warm, not hot, just warm, and can feel the same at the + busbar that feeds the BATT1,1, 2 switches. Going to chech those out and run an extra cable, , managed to get some 70 amp stuff today.
Please keep any advice coming, same applies to nigel and others.

Yep the second diagram you emailed looked fine.

Anything getting warm is either due to overloaded cable or poor connections or poor crimps.

10mm² cable should be Ok for 30 or 40 amps, unless we are looking cable lengths greater than about a couple of metres and for at least 90 amps for short direct connections. I believe it is sold as 70 amp cable.

Dont forget all the same considerations apply equally to the negative circuitry as to the positive.

Id think Chris_ Robs suggestion to measure volts drops a good idea. If you dont need long multimeter connections so much the better. You are looking to make these measurements at the highest possible currents ie when charging a partly discharged battery. Do be careful working close to rotating pulleys and belts.

You refer to switches in the plural. This presumably mens you have separate selector switches or the engine supply/ alternator output and the feed to the domestic services panel?

How is you solar panel connected. Just to the domestic battery bank ?