alternator wiring

[Alvin]

Over the last weeks my electrically capable friend and I have been fitting an alternator and new wiring to my old SL3. The particular Bosch alternator was suggested by the dealer as charging at 500RPM upwards and it does on his test rig and as I did not want to change engine pulley seemed good plan. The unit fitted well after making a steel tubular spacer between original rear bracket on engine and rear lug on Alt. The main connection points on rear of Alt. are Battery + and Ign. ve+? chassis to ve-. From the ve+ side of battery we mounted a double acting ingnition switch,one line to start sw. to starter, second line to ignition light also to ve+ on battery. Engine starts, on button with ignition switch on.

As I look at diagram today cannot see why light is also in a ve+ circuit or should this circuit drop out once full charge revs are met therefore light goes out on oprn circuit. I really wanted to attach diag.but never seem to be able to use the attaching system ( copy & paste would be so easy)?

[Robin2]

Over the last weeks my electrically capable friend and I have been fitting an alternator and new wiring to my old SL3. The particular Bosch alternator was suggested by the dealer as charging at 500RPM upwards and it does on his test rig and as I did not want to change engine pulley seemed good plan. The unit fitted well after making a steel tubular spacer between original rear bracket on engine and rear lug on Alt. The main connection points on rear of Alt. are Battery + and Ign. ve+? chassis to ve-. From the ve+ side of battery we mounted a double acting ingnition switch,one line to start sw. to starter, second line to ignition light also to ve+ on battery. Engine starts, on button with ignition switch on.

As I look at diagram today cannot see why light is also in a ve+ circuit or should this circuit drop out once full charge revs are met therefore light goes out on oprn circuit. I really wanted to attach diag.but never seem to be able to use the attaching system ( copy & paste would be so easy)?

 

There was an extended discussion about alternator wiring on another thread a couple of days ago. The key switch should go to the Ign on the alternator through the warning light. Current will flow into the field winding until the alternator's generated voltage matches the battery voltage - then the current will stop and the light will go out.

[Gibbo]

I can't even understand the question.

[paulcatchpole]

I can't even understand the question.

 

I think he's wondering why the charge warning light / field light has +ve on the non-alternator side of it... I think.

 

For the OP, the light lights up, while current is flowing through it to the field windings of the alternator, to excite it.

 

Once the alternator is excited and running, +ve appears on both sides of the field / warning lamp and it goes out.

 

I would hazard a guess that you aren't feeding the alternator with enough field current for it to excite.

 

Would suggest either upping the wattage of the bulb in the warning lamp, or sticking a (erm, 40ohm do it, Gibbo?) cermet resistor in parallel with the lamp.

 

You could try giving the engine some beans in neutral, to see if it'll eventually come up, as well.

 

PC

[WotEver]

Hmmm, Paul, why are you assuming it's not working?

 

I've re-read the OP several times and whilst I'm still unsure exactly what the question is, I don't believe it's "Why doesn't my alternator work?"

 

Tony

[paulcatchpole]

Hmmm, Paul, why are you assuming it's not working?

 

I've re-read the OP several times and whilst I'm still unsure exactly what the question is, I don't believe it's "Why doesn't my alternator work?"

 

Tony

 

I was going by the thread subtitle, Tony:

 

"alternator wiring ignition light does not go out "

 

PC

[Tony Brooks]

Question 1 - what does he mean by a double acting ignition switch? I assume he means an off-aux-start one but who knows.

 

Question 2 - what does "second line to ignition light also to ve+ on battery" mean. This sounds as if he may have two battery feeds to the switch and no ign.sw. to warning lamp connection.

 

Question 3 - what are the actual terminal markings on the alternator, I doubt they are shown as the OP quotes.

 

At the moment we are just speculation and possibly giving the OP some wrong ideas. I know PC and Alvin have got it right but can the OP understand what is being said.

 

Perhaps the OP should try to describe the wiring again but using the terminal marking on the alternator.

[paulcatchpole]

At the moment we are just speculation and possibly giving the OP some wrong ideas.

 

Wise words, I did rather rush in with an assumption...

 

Be interesting to hear more from the OP.

 

PC

[WotEver]

I was going by the thread subtitle, Tony:

 

"alternator wiring ignition light does not go out "

 

PC

Well, if you're going to read the whole title then I'm not going to play any more

 

T.

 

That's just cheating

[paulcatchpole]

That's just cheating

 

I'll try and be less diligent in future...

 

PC

[WotEver]

I'll try and be less diligent in future...

 

PC

Please do. It's most disconcerting

 

T.

[cereal tiller]

i think it is time to consult the mighty dean s?

[blodger]

i think it is time to consult the mighty dean s?

The main connection points on rear of Alt. are Battery + and Ign. ve+? chassis to ve-. From the ve+ side of battery we mounted a double acting ingnition switch,one line to start sw. to starter, second line to ignition light also to ve+ on battery. Engine starts, on button with ignition switch on.

 

I am reading this double acting ignition switch as being akin to a double pole one but using one side to put a live to the start button that goes to the starter solenoid. The other goes to the charge warning light but it says the return also goes back to the battery but to light up must be on the negative not the positive but should be to the I or D+ on the alt which I think he is calling I Ign.

 

Perhaps that will aid Dean in drawing the diagram?

Edited June 22, 2011 by blodger

[Robin2]

The problem her is that the OP doesn't realize how quickly answers appear on this forum. If s/he stays away for a week we can design a whole wiring system for (insert your object of choice).

[DeanS]

i think it is time to consult the mighty dean s?

 

I read this thread with a smile on my face, and a commitment to not cause any further confusion I do have a lovely picture though

[Alvin]

The main connection points on rear of Alt. are Battery + and Ign. ve+? chassis to ve-. From the ve+ side of battery we mounted a double acting ingnition switch,one line to start sw. to starter, second line to ignition light also to ve+ on battery. Engine starts, on button with ignition switch on.

 

I am reading this double acting ignition switch as being akin to a double pole one but using one side to put a live to the start button that goes to the starter solenoid. The other goes to the charge warning light but it says the return also goes back to the battery but to light up must be on the negative not the positive but should be to the I or D+ on the alt which I think he is calling I Ign.

 

Perhaps that will aid Dean in drawing the diagram?

Hi Blodger,

Sorry that I have confused everyone, you are right it is a double pole sw. As I may have said in orig.topic start, the Alernator has been tested and works fine. The light not going out is the issue and have learnt that this should go out with the positive output from Alt. We are going to check with Taco that revs are high enough and to check output voltage & current from I term. Might also change lamp to very low resistance one (assuming existing is high-need to check with electrical friend. Ref diagram I wish there was an easier way, other than via Http:// etc. any suggestions please?

cheers Alvin

[Tony Brooks]

Hi Blodger,

Sorry that I have confused everyone, you are right it is a double pole sw. As I may have said in orig.topic start, the Alernator has been tested and works fine. The light not going out is the issue and have learnt that this should go out with the positive output from Alt. We are going to check with Taco that revs are high enough and to check output voltage & current from I term. Might also change lamp to very low resistance one (assuming existing is high-need to check with electrical friend. Ref diagram I wish there was an easier way, other than via Http:// etc. any suggestions please?

cheers Alvin

 

 

Sorry that I do not post out £8.00 books FOC to everyone who thinks they want one rather than look on the web but you will find all the generic diagrams you need on www.tb-training.co.uk in the electrical course notes. If the new alternator is odd you may need a digram for that as will but I do not think it is. The notes also tabulate recognised alternatro terminal desigantions.

 

If you are using an ordinary on-off double pole switch with one pole supplying the stater solenoid and other other the warning lamp then there are two possibilities:

 

1. You are turning it off as soon as the engine fires so you isolate the warning lamp circuit BEFORE the alternator has energise.

 

2. You have other things (warning lamps etc) fed off the charge warning lamp terminal on the switch as soon as you turn the switch off to stop the starter an energised alternator will "back feed" through the switch to try to supply the other circuits. That illuminates the warning lamp.

 

I Think you really should stick with convention and use a key type ignition switch and feed the warning lamp from the aux. terminal and the starter from the start terminal. That way everyone knows what to expect will be far better able to give help.

 

You should not need a bulb with a rating higher than 2.2 watts and 1.5 watts is normally fine. LEDs and lamps with "grain of wheat" bulbs (dolls house bulbs) are not. I think the problem is with the wiring and I am far from convinced that you have not done something odd like connecting the warning lamp to the taco terminal. This is why I asked you re-describe how you have wired the alternator using the terminal designations on the actual machine.

 

Your warning lamp circuit should be:- battery feed - switch - bulb - alternator warning lamp terminal usually marked D or W/L. The feed should be present all the time the alternator is running, otherwise you will get no warning lamp indication of belt or alternator failure.

[blodger]

Sorry that I do not post out £8.00 books FOC to everyone who thinks they want one rather than look on the web but you will find all the generic diagrams you need on www.tb-training.co.uk in the electrical course notes. If the new alternator is odd you may need a digram for that as will but I do not think it is. The notes also tabulate recognised alternatro terminal desigantions.

 

If you are using an ordinary on-off double pole switch with one pole supplying the stater solenoid and other other the warning lamp then there are two possibilities:

 

1. You are turning it off as soon as the engine fires so you isolate the warning lamp circuit BEFORE the alternator has energise.

 

2. You have other things (warning lamps etc) fed off the charge warning lamp terminal on the switch as soon as you turn the switch off to stop the starter an energised alternator will "back feed" through the switch to try to supply the other circuits. That illuminates the warning lamp.

 

I Think you really should stick with convention and use a key type ignition switch and feed the warning lamp from the aux. terminal and the starter from the start terminal. That way everyone knows what to expect will be far better able to give help.

 

You should not need a bulb with a rating higher than 2.2 watts and 1.5 watts is normally fine. LEDs and lamps with "grain of wheat" bulbs (dolls house bulbs) are not. I think the problem is with the wiring and I am far from convinced that you have not done something odd like connecting the warning lamp to the taco terminal. This is why I asked you re-describe how you have wired the alternator using the terminal designations on the actual machine.

 

Your warning lamp circuit should be:- battery feed - switch - bulb - alternator warning lamp terminal usually marked D or W/L. The feed should be present all the time the alternator is running, otherwise you will get no warning lamp indication of belt or alternator failure.

 

Hi Blodger,

Sorry that I have confused everyone, you are right it is a double pole sw. As I may have said in orig.topic start, the Alernator has been tested and works fine. The light not going out is the issue and have learnt that this should go out with the positive output from Alt. We are going to check with Taco that revs are high enough and to check output voltage & current from I term. Might also change lamp to very low resistance one (assuming existing is high-need to check with electrical friend. Ref diagram I wish there was an easier way, other than via Http:// etc. any suggestions please?

cheers Alvin

 

From my reading and perhaps Alvin will confirm, he uses the double pole switch as an ignition on switch with a push button in line with one pole and the solenoid for starting.

The other pole enegises the alternator through the charge warning light so that the ignition switch is left on just like having a key in and turned on the conventional one.

 

Clearly there is something amiss in where the connection is made at the alternator in all probability as you have tried to explain.

 

Alvin I can recommend you look at Tony's site not just at the pages specific to your current problem but generally. The other much vaunted web site for myth shattering and explanation of things battery electrical is Smartguage. If you can manage CWDF you can visit these two sites. just google

[WotEver]

... Smartguage. <snip> just google

Although you'll have more luck if you Google for smartgauge

 

Tony

 

http://www.smartgauge.co.uk/technical1.html

[Alvin]

Although you'll have more luck if you Google for smartgauge

 

Tony

 

http://www.smartgauge.co.uk/technical1.html

Thanks to all who have contributed to this issue, yesterday Monday 27th I decided to attach an extra earth line from alternator bracket and the battery. Started engine and the light went out and the ammeter came to life and showed a charge about 20amp I think, but on negative side, so I think the wires need reversing. Anyway thanks again to everyone. Will have a look later at book opportunity.

cheers Alvin

[WotEver]

... the ammeter came to life and showed a charge about 20amp I think, but on negative side, so I think the wires need reversing.

Just to be clear, you do mean the wires to the ammeter, don't you?

 

Tony

[Gibbo]

Just to be clear, you do mean the wires to the ammeter, don't you?

 

And if so, why?

 

Has this boat spent all its life with the ammeter pointing the wrong way?

 

I suspect there is more than we have been told.

[WotEver]

And if so, why?

The clue's in the OP:

 

Over the last weeks my electrically capable friend and I have been fitting an alternator and new wiring to my old SL3.

 

I think I'd doubt the description of the friend...

 

Tony

[Gibbo]

I think I'd doubt the description of the friend...

 

Well it was that "electrically capable" part that made me believe they can't possibly have got it so badly wrong so it must have always been like that. Perhaps "in" was missing