split charge relay wiring woes

[richievtu]

hello
I have wired one of the above in my boat as the original system had been long disconnected, I have kept it simple and used the method I have previously & checked with diagrams online but this time something isnt quite right!
The basic 30A relay is split between 2 batteries, starter & service, I have connected the trigger wire to the only wire on the alternator that is live once the engine has started. The alternator isnt original and is connected to a seperate regulator, although there is also one on the alternator? the regulator is also wired to the glowplug light which seems to double as an alternator light?
So.. the issue is that the leisure battery doesnt appear to be charging, there is approx 13.5v + at one side of the relay, but not the other, its about 13v, the same charge as the battery. The starter battery is charging.
Is 0.5v usually lost through the relay or is it not working?
Or do relays need a higher input voltage before they are triggered?
The other thing is that I can hear the relay click as the ignition is switched to the glowplug heat position and at this point there is about 3v registered at the alt feed wire. The amp gauge is showing approx 15a on quick tickover.
I think I have covered everything, any input appreciated as I have run out of ideas and bored of heaving the service battery out to charge!

 

[ianj99]

hello
I have wired one of the above in my boat as the original system had been long disconnected, I have kept it simple and used the method I have previously & checked with diagrams online but this time something isnt quite right!
The basic 30A relay is split between 2 batteries, starter & service, I have connected the trigger wire to the only wire on the alternator that is live once the engine has started. The alternator isnt original and is connected to a seperate regulator, although there is also one on the alternator? the regulator is also wired to the glowplug light which seems to double as an alternator light?
So.. the issue is that the leisure battery doesnt appear to be charging, there is approx 13.5v + at one side of the relay, but not the other, its about 13v, the same charge as the battery. The starter battery is charging.
Is 0.5v usually lost through the relay or is it not working?
Or do relays need a higher input voltage before they are triggered?
The other thing is that I can hear the relay click as the ignition is switched to the glowplug heat position and at this point there is about 3v registered at the alt feed wire. The amp gauge is showing approx 15a on quick tickover.
I think I have covered everything, any input appreciated as I have run out of ideas and bored of heaving the service battery out to charge!

On side of the relay coil should be at 0V (bat negative and the other will then receive 13v when the alternator is working, thus connecting the alternator to the leisure battery.
So if you measure all 4 terminals on the relay with the engine running, if its working, 3 will all be at the charging voltage and one will be 0v.
With the engine stopped (relay open) 1 will show the leisure battery voltage, one 0v and the other 2 no significant voltage.

May just be a faulty relay or bad earth.

I

 

[VicS]

Totally confused I am afraid.

A diagram of how you have wired this would be worth a thousand attemps to explain it in words.

Puzzled by your reference to two regulators. What external regulator is installed

puzzled as to why the glowplug light comes into all of this.

what is the relay you have used. Is it proper charge control relay or a VSR or something else.

You refer to one side of the relay and the other ... I'd expect four teminals to the relay. Two to the coil and two being the contacts.

A diagram please

 

[earlybird]

Like VicS i'm confused, but one change I would make straight away would be to completely separate the heater plug circuit from the ignition/charging circuit. Seems to me that you stand a good chance of ruining some fairly pricey plugs.

 

[richievtu]

not as confused as I am, probably not explained as well as I thought!
atatched should be a diagram of a similar setup, with the engine running there is about 13.6v ( rising to nearly 14v) at term 86, the same at term 30 & 13v at term 87.
I beleieve the original alternators had seperate regulators, the alternaor in question is a newer replacement that appears to have a built in regulator but is still connected to the secondary regulator, not sure why but as the starter battery is charging ok I intended to leave it alone.

 

[VicS]

Thats Ok.

When the alternator is running its output voltage will be applied to the relay coil (86), the other end of the coil being grounded (85)

the relay will close (terminals 30 and 87) connecting the leisure battery to the starter battery and charging circuit.

Your relay appears not to be working if the volts at terminal 87 do not rise when 14 volts is applied to 86.
BUT if your leisure battery is at 13 volts something must be charging it or it would be 12.something or less.

Check the grounding of 85.

You say this is a diagram of "a similar set up" .... what we need is a diagram of your set up including how the glowplugs and their relay and warning light is wired

How do your glow plugs operate. Automatically when the ignition is tuned on .. like they do in a car ... or when the key is in a "preheat" position.

Personally I'd want to sort out this business of two regulators. OK if the external one is some special gizmo to enhance the charging but a puzzle otherwise.

 

[richievtu]

The glowplugs operate not when the ignition is in on position but when the key is turned and held, I will draw a diagram when im back on board, apart from the glowplug wiring the diagram is exactly the same as how I did mine.
The leisure battery has just been trickle charged so this might explain the full 13v?
As for the regulator situation, I may have to do another post once I have sketched how its configured!

 

[VicS]

Ok if the battery has been charged that explains why it 13 volts and not much lower

It seems to be coming back to the relay.

Earlier you said you could hear it click when the key switch is turned to the preheat position ( sorry I missed that first time round hence the later question) BUT The charge contral relay should not click ... you should however hear the glowplug relay operate.

The charge control relay should not operate until the alternator is generating and the charge warning light goes out. Then you should see the volts at terminal 87 rise to near enough the same as terminal 30. ( but with the engine running you probably wont hear the relay operate

I think it would be sensible to disconnect 85 and 86 and check the coil for continuity .

If the coil is Ok check that the volts at terminal 85 remains at near enough zero. If it rises then it indicates a bad negative connection.

Got to sort out this glowplug wiring. I think it might be red herring but until we see how its all wired we cant figure out what might be happening.

Is all this on an engine and engine manufacturers control panel which we should be able to check on.

 

[maxi77]

It may be the relay is not functioning as a result of being overloaded. Much higher current flows than 30 amps can flow in the early stages of charging if the house batteries are discharged and will effectively suck i9in all the alternator output. On my Bongo and the windlass battery I only use the 30 amp vsr to switch a 70 amp relay which carries the main charging current. If you have a high output alternator I would suggest a relay rated at the alternator output.

 

[VicS]

It may be the relay is not functioning as a result of being overloaded. Much higher current flows than 30 amps can flow in the early stages of charging if the house batteries are discharged and will effectively suck i9in all the alternator output. On my Bongo and the windlass battery I only use the 30 amp vsr to switch a 70 amp relay which carries the main charging current. If you have a high output alternator I would suggest a relay rated at the alternator output.

In the case in point though the leisure battery has been charged and is at 13 volts already

 

[maxi77]

In the case in point though the leisure battery has been charged and is at 13 volts already

Though why is the relay not open when the alternator side is at 13.5V. In reality such relays usually remain open for some time after the charging supply has been removed as the 'protected' battery volts will still be high enough to keep it open for some minutes. I have never seen a .5V drop over such a relay.

 

[VicS]

Though why is the relay not open when the alternator side is at 13.5V. In reality such relays usually remain open for some time after the charging supply has been removed as the 'protected' battery volts will still be high enough to keep it open for some minutes. I have never seen a .5V drop over such a relay.

You are thinking about VSRs.
The relay in question, as far as we can tell, is a simple relay and according to the diagram is controlled by the warning light circuit. As soon as the alternator is up and running the relay closes.
You'll find a similar circuit to the one posted in the Lucas catalogue.

I agree there should not be a 0.5 volt drop across the contacts. In this instance I think you will find that it is not a volts drop as such but the difference between the alternator output/engine battery and the charged leisure battery. I think the relay is not operating.

 

[richievtu]

thanks for the input, I will have a look at the glowplug wiring, try to separate it from the system, incidentally there is no glowplug relay, they switch off when you release the starter key, hopefully! its 60,s technology and most of it has been fiddled with over the years.
the split charge relay also definately clicks when the ignition is switched on but before the glowplugs are so there is something clearly wrong there.
I have swapped the relay for a new one which gives the same results. The next thing I will check is the earth as suggested and update!

 

[VicS]

he split charge relay also definately clicks when the ignition is switched on but before the glowplugs are so there is something clearly wrong there.
I have swapped the relay for a new one which gives the same results. The next thing I will check is the earth as suggested and update!

I am just as puzzled as before.

If the relay clicks then its operating, so the earth must be Ok but check it all the same.
If you have tried a new one that more or less rules out a defective relay.

But you cannot have that 0.5 volts difference if the relay is operating correctly and its contacts are good.

Something I am missing !

 

[nimbusgb]

Two heavy wires off the big terminals - One to battery A positive other to battery B positive. The other little wire is earth and goes to the negative terminal of the batteries. ( you need common negative anyway )

Otherwise it sounds as if the negative has been connected to the alternator and the relay is pulled in until voltage comes up on the Alt and then the whole device is at around 12v and it all falls apart.

The VSR senses its voltage directly off the battery terminals themselves not off the little ( ground ) wire.

It would help to know whose VSR you are using.

 

[pvb]

It would help to know whose VSR you are using.

If you read through the thread carefully, you'll see it's not a VSR, it's just a simple relay.

 

[richievtu]

a bit more info before I have a tinker, the earth wire from the relay goes to the alternator mounting bracket?
Also what should the cable be rated at that goes from alt to relay, does it need to be as thick as those going from relay to battery?
when the ignition is switched to the first postion before glowplugs are heated there about 4 volts measured at this cable, possibly why the relay is clicking, surely it should read 0 until the engine has started?
still more question marks!

 

[pvb]

a bit more info before I have a tinker, the earth wire from the relay goes to the alternator mounting bracket?
Also what should the cable be rated at that goes from alt to relay, does it need to be as thick as those going from relay to battery?
when the ignition is switched to the first postion before glowplugs are heated there about 4 volts measured at this cable, possibly why the relay is clicking, surely it should read 0 until the engine has started?
still more question marks!

OK, the wire from relay contact 85 can go to the alternator bracket, but make sure it's a good connection.

Disconnect relay contact 86 from the alternator, and connect it instead to the ignition switch terminal which is live when the engine is on. This wire only carries the current needed to activate the relay, so it can be fairly light.

The cables from relay contacts 30 and 87 to the batteries must be heavy cables capable of carrying the full charging current.

When the ignition is on, the batteries will be connected and will both be charged by the alternator. When the ignition is off, the batteries will be separated, and domestic loads won't discharge the starting battery.

The simple relay system you have isn't ideal, but it should work for your needs.

 

[VicS]

still more question marks!

I'll have a go at some answers.

the earth wire from the relay goes to the alternator mounting bracket?
Yes this should be a good earth/connection to the negative.

Also what should the cable be rated at that goes from alt to relay, does it need to be as thick as those going from relay to battery?
The wiring to terminals 86 and 85 only carry the relatively small current for the relay coil so can be much lighter than those that carry the main charging currents.
The wires to terminals 30 and 87 should be heavy enough to carry the full alternator output.

when the ignition is switched to the first postion before glowplugs are heated there about 4 volts measured at this cable, possibly why the relay is clicking, surely it should read 0 until the engine has started?
When the ignition is switched on a current flows from the key switch via the ignition warning light to the alternator to provide an initial field current. Without it the alternator probably would not start to generate. Once it is genearting it supplies its own field current and the warning light goes out.
At this point the volts at the warning light terminal of the alternator will have risen to ( depending on the exact circuitry of the alternator) about the same as the battery volts. Until the alternator is running there will be a voltage there, I m not sure what but 4 volts surprises me a little.

Several thoughts now cross my mind. It is the wrong type of relay and it is closing at 4 volts when it should not close until they have risen to at least 12.
The warning light is a larger wattage than it should be leading to the volts at the alternator connection being higher than they should be.
The glowplug circuit is tangled up in this in a way that is affecting it.

I have not managed to find a spec for a charge control relay ( I've seen it before, its out there somewhere, but you know what its like finding information when you actually need it.)

A worry that now surfaces is that if the relay closes when the ignition is switched on and before the engine is started it is effectively connecting the leisure battery in parallel with the starter battery. This means that it will share the load of the starter motor with the starter battery. This could overload the wiring and the relay contacts. Maybe this has caused them to burn up.

I think I would want to check that the relay in use is the correct type for the application. I do not believe it should close at 4 volts ... It must not close at 4 volts .. it must not close until the engine has started and the alternator is generating.

 

[richievtu]

I had though the relay may be the wrong type, I had this along with the spare I tried hanging around for a while so unsure of the specs, didnt realise there were so many types until recently. I will see what else I have.
I have also changed the warning light bulbs for 4 watt versions as the originals were only 1.2v & thought they may have been part of the problem being underpowered, according to my book they should be between 2&4w?
they are also producing a v slight glow when up & running.