Wiring for Alternator

[Wykeham 99]

Hello all!

 

Although I have read (many times!)Ian Cornish's excellent article on the Technicalities CD on the subject of wiring alternators, I am still in need of some assistance. I have a LRA100N (18ACR) alternator fitted to my TR3A which is coupled to a wiring loom via a plug in block. The wires in this loom are a thin yellow (for the ignition light) and a thick brown wire and a thinner brown wire. At the moment, the thick and thin brown wires are joined together in the loom and are routed to the solenoid connection via a large ring tag. The yellow wire is connected to the ignition light lead. The ammeter only reads discharge - it is not recording the charge from the alternator. Where should the brown wires be connected? I have retained the control box for connection purposes only and, at the moment, A1 and A are linked. Secondly, am I correct in thinking that the LRA100N is a 45amp alternator and so I will need to put a shunt across the ammeter connections to reduce the amps across the instrument?

 

I realise that I am revisiting an old topic but a definite 'do this and do that' would be much appreciated.

 

Confused of Suffolk

[ianc]

I think that your problem is caused by the joining of the two brown wires - they need to be separate. For a 3-wire alternator, you should connect thus:

3-Wire Alternator: remove the Control Box and connect as follows:

(a) Link D (the heavy lead from the dynamo) to the cables which connected to A (from the Ammeter) and A1 (from the Ignition/Lighting Switch). At the alternator, connect the D lead to the terminal marked + (a large, push-on, 35 amp, spade connector will be required).

( Link the lead F from the dynamo's field coil (the light duty lead) to the lead from the Ignition Warning Light (the second and smaller of the leads which terminated at D). At the alternator, connect the F lead to the terminal marked IND (a small, push-on, 17.5 amp, spade connector will be required).

© Run a new lead, rated at 35 amps (size 65/0.30), from the terminal marked Sense or B+ on the alternator (a large, push-on, 35 amp, spade connector will be required) to the connection on the starter solenoid that is fed directly from the positive terminal of the battery (a large ring-tag will be required).

 

Box Original Duty New Duty Linking

E To Earth Redundant

D {To Dynamo -ve (heavy lead) To Alternator +ve ┐

{To Ignition Warning Light To Ignition Warning Light ┐ │

F To Dynamo Field Coil (light lead) To Alternator IND ┘ │

A To Ammeter To Ammeter ┤

A1 To Ignition Switch Terminal 1 (TR4) To Ignition Switch Terminal 1 ┘

or Lighting Switch Terminal A (TR2/3) or Lighting Switch Terminal A

From Alternator Sense or B+ ┐

To Starter Solenoid ┘

(Battery +ve)

I have cut this from a Word version of my article as the linking is not so clear in the CD (transposition to some other Word Processing system, I imagine). If you would like the Word version, just e-mail me direct:

ifcornish@btinternet.com

 

Ian Cornish

[ianc]

I think that your problem is caused by the joining of the two brown wires - they need to be separate. For a 3-wire alternator, you should connect thus:

3-Wire Alternator: remove the Control Box and connect as follows:

(a) Link D (the heavy lead from the dynamo) to the cables which connected to A (from the Ammeter) and A1 (from the Ignition/Lighting Switch). At the alternator, connect the D lead to the terminal marked + (a large, push-on, 35 amp, spade connector will be required).

( Link the lead F from the dynamo's field coil (the light duty lead) to the lead from the Ignition Warning Light (the second and smaller of the leads which terminated at D). At the alternator, connect the F lead to the terminal marked IND (a small, push-on, 17.5 amp, spade connector will be required).

© Run a new lead, rated at 35 amps (size 65/0.30), from the terminal marked Sense or B+ on the alternator (a large, push-on, 35 amp, spade connector will be required) to the connection on the starter solenoid that is fed directly from the positive terminal of the battery (a large ring-tag will be required).

 

Box Original Duty New Duty Linking

E To Earth Redundant

D {To Dynamo -ve (heavy lead) To Alternator +ve ┐

{To Ignition Warning Light To Ignition Warning Light ┐ │

F To Dynamo Field Coil (light lead) To Alternator IND ┘ │

A To Ammeter To Ammeter ┤

A1 To Ignition Switch Terminal 1 (TR4) To Ignition Switch Terminal 1 ┘

or Lighting Switch Terminal A (TR2/3) or Lighting Switch Terminal A

From Alternator Sense or B+ ┐

To Starter Solenoid ┘

(Battery +ve)

I have cut this from a Word version of my article as the linking is not so clear in the CD (transposition to some other Word Processing system, I imagine). If you would like the Word version, just e-mail me direct:

ifcornish@btinternet.com

 

Ian Cornish

 

Sorry - the linking looked OK until I posted the reply - it has become deranged and it does not appear possible to correct it! e-mail me!

Ian

[littlejim]

My two brown wires also came joined by the manufacturer of the Moss alternator.

I ended up after much agonising over wiring diagrams and recall of schoolboy physics, putting them straight into the ammeter just like the generator was. I used the voltage regulator box as a junction box after cutting the straps at the back of it, so the wire to the ammeter came from there and the brown wires made the connection there after a mod to the big washer supplied.(Mine's a 4A)

No fires so far.

Edited August 25, 2010 by littlejim

[ianc]

Re-reading Wykeham's description, I can see that he has - in effect - connected the alternator to the battery direct via the terminal on the solenoid. Hence, any charging of the battery is NOT passing through the ammeter, which is why it never shows any charge! When lights etc. are used, discharge from the battery passes throught the ammeter to feed the circuits, as he has described. Hence, when the car is running, the alternator is charging the battery invisibly, but the circuits are taking current from the battery as indicated by the ammeter - I would expect that the (invisible) inflow to the battery is matching the (visible) outflow!

 

SOLUTION: The two, linked, brown wires should be removed from the solenoid and connected to the 2 wires which were connected to A (from Ammeter) and A1 (from Ignition Switch Terminal 1 on TR4; from Lighting Switch Terminal A on TR2/3).

 

Ian Cornish

[littlejim]

Re-reading Wykeham's description, I can see that he has - in effect - connected the alternator to the battery direct via the terminal on the solenoid. Hence, any charging of the battery is NOT passing through the ammeter, which is why it never shows any charge! When lights etc. are used, discharge from the battery passes throught the ammeter to feed the circuits, as he has described. Hence, when the car is running, the alternator is charging the battery invisibly, but the circuits are taking current from the battery as indicated by the ammeter - I would expect that the (invisible) inflow to the battery is matching the (visible) outflow!

 

SOLUTION: The two, linked, brown wires should be removed from the solenoid and connected to the 2 wires which were connected to A (from Ammeter) and A1 (from Ignition Switch Terminal 1 on TR4; from Lighting Switch Terminal A on TR2/3).

 

Ian Cornish

 

Ian,

I used the VTR published guide at first, and it tells you to connect directly to the solenoid terminal, which you correctly point out bypasses the ammeter.

I eventually worked out that it had to go from the alternator directly to the ammeter if I wanted the ammeter to show what was going on.

The worry then, for electrically challenged restorers,(moi) is whether the ammeter can take it before turning into smoke. The wimps way out is to put a shunt across the ammeter terminals I guess, which would then send it happily on its way to whatever gadget without bothering the meter itself. You could play with the diameter of the shunt according to what you wanted to see on the ammeter.

Sounds good until you have a go at getting to the back of the ammeter.

 

One of our other contributors has put the shunt across the wires to and from the ammeter in a location where it much more accessible.

I am too dumb to nut out clever stuff like that, and of course have spent lots of time behind the dash instead. However I now know you take the driver seat out first (RHD).

 

Later: Some of the problem relates to whether you try to provide a guide in 'follow these steps' format or a 'this is the result we are after' format. At first I wanted the former, when it didn't work I had to nut out the latter.

Later still: I personally found your articles a godsend at the time I was putting the alternator in, otherwise would have been stonkered. The car worked, which was the primary aim. Was happy to spend time later getting it the way I wanted it.

Edited August 25, 2010 by littlejim

[Dave Larnder]

Re-reading Wykeham's description, I can see that he has - in effect - connected the alternator to the battery direct via the terminal on the solenoid. Hence, any charging of the battery is NOT passing through the ammeter, which is why it never shows any charge! When lights etc. are used, discharge from the battery passes throught the ammeter to feed the circuits, as he has described. Hence, when the car is running, the alternator is charging the battery invisibly, but the circuits are taking current from the battery as indicated by the ammeter - I would expect that the (invisible) inflow to the battery is matching the (visible) outflow!

 

SOLUTION: The two, linked, brown wires should be removed from the solenoid and connected to the 2 wires which were connected to A (from Ammeter) and A1 (from Ignition Switch Terminal 1 on TR4; from Lighting Switch Terminal A on TR2/3).

 

Ian Cornish

 

Hi Ian

This is exactly what I get on my Moss alternator, BUT I have 4 wires coming from the loom. There is a Light wire joined to a medium weight wire by a ring terminal, another medium weight wire with its own same size terminal, and also a heavy weight wire again on its own same size terminal, all of which fit the solenoid terminal size. All wires are plain brown.

I have connected them all to the solenoid EXCEPT the medium weight wire which I have taped off very carefully as I don't know where it goes to, because if I touch it to the solenoid terminal, I get a massive discharge showing all the time. With the way I have connected it up I don't get any charging shown when all accessories etc. are turned off ( Lights and windscreen wipers) but immediately I turn one or both of them on a get a discharge reading on the ammeter. Now I know that the alternator is charging the battery when driving, because I would never have got to Le Mans if it were not so. So that bears out your solution., however what do I do with the medium weight one which I have taped off?

Sorry for the non technical sizing of the wires as I don't understand electrics at all, it has always been the bane of my life.

Dave

[Dave Larnder]

Ian,

I used the VTR published guide at first, and it tells you to connect directly to the solenoid terminal, which you correctly point out bypasses the ammeter.

I eventually worked out that it had to go from the alternator directly to the ammeter if I wanted the ammeter to show what was going on.

The worry then, for electrically challenged restorers,(moi) is whether the ammeter can take it before turning into smoke. The wimps way out is to put a shunt across the ammeter terminals I guess, which would then send it happily on its way to whatever gadget without bothering the meter itself. You could play with the diameter of the shunt according to what you wanted to see on the ammeter.

Sounds good until you have a go at getting to the back of the ammeter.

 

One of our other contributors has put the shunt across the wires to and from the ammeter in a location where it much more accessible.

I am too dumb to nut out clever stuff like that, and of course have spent lots of time behind the dash instead. However I now know you take the driver seat out first (RHD).

 

Later: Some of the problem relates to whether you try to provide a guide in 'follow these steps' format or a 'this is the result we are after' format. At first I wanted the former, when it didn't work I had to nut out the latter.

 

 

Littlejim

I find it easier to leave the drivers seat in position and sit on it when I have first removed the 4 thumb screws that hold the crackle black panel to the dash and pull it forward to make things easier to get at. However be carefull that you have enough coiled or looped oil pressure pipe behind the panel and enough connection for the temp. gauge as well.

Dave

[ianc]

One of the reasons behind my choice of the LRA101 was that it is rated at 34 amps. In practice, I have never seen a charge rate greater that about 28 amps, and that has been the depths of winter when the car hasn't been run for about 3 weeks, and that charge rate lasts only a few seconds. Hence, I don't worry about my ammeter getting cooked! If I had fitted a 60 amp rating alternator, I would have either put a shunt onto my ammeter or tried to find a meter scaled +60/0/-60 amps.

 

Why Dave should have four wires in the alternator loom, I have no idea! The fact that they are all the same colour strikes me as stupid on the supplier's part! I would have expected the supplier to provide comprehensive instructions, but, from what I have read, purchasers have been left to suck it and see, which is unsatisfactory. Some have used my article as a guide, but I have no information on the wiring loom included in the "kit" which they have purchased, so there is a knowledge gap there. Perhaps someone could e-mail me (ifcornish@btinternet.com) the instructions with which their kit was issued and I might then be able to assist further?

 

I have a feeling that the suppliers may be assuming that the cars involved have a voltmeter, so direct connection (via the solenoid terminal) to the battery would be fine. However, we have ammeters in our TRs (TR2-6) and, after years of running with a dynamo, it is disturbing not to see a charge going into the battery, and a hefty discharge when the lights, electric fan etc are turned on. The saving grace is that the warning light should glow if the alternator is not coping with the load.

 

Ian Cornish

[littlejim]

Littlejim

I find it easier to leave the drivers seat in position and sit on it when I have first removed the 4 thumb screws that hold the crackle black panel to the dash and pull it forward to make things easier to get at. However be carefull that you have enough coiled or looped oil pressure pipe behind the panel and enough connection for the temp. gauge as well.

Dave

 

Different setup in the 4A, no thumbscrews, no crackle panel.

[Dave Larnder]

Littlejim

 

I see you have the good sense to use the TR2/3/3A forum instead of the 4a, hence the reason I assumed (wrongfully) that you had one of those magnificent sidescreen cars we all love so much.

For your info, I have scanned in, the instructions that I got from Moss and e mailed it to Ian Cornish, so lets hope he can unravel our problem

Keep TR-ing

Dave

[Wykeham 99]

Hello all

 

Many thanks for all the wise words! Problem now solved (as suggested) by putting both the brown wires to A1/A on the control box (which I have linked together). Not much + charge showing as engine is running but no heavy - when the lights are turned on so I presume that all is well as the ammeter needle sits happily in the central position.

 

Thanks to all

 

Less confused of Suffolk!

[ianc]

Dave Larnder sent me a copy of the instructions issued by Moss.

It doesn't help that Moss has not properly copied the sheet (from AC, the maker of the alternator which Moss sells) -so the far and bottom right edges are missing! Having read these instructions, this is my response:

 

I am appalled by this! And now I can see why some TR people have been suffering difficulties in swapping to an alternator. AC's technical people should be ashamed of themselves for producing such unclear and downright confusing instructions. Although I know what should be going on, I cannot equate it with these diagrams and the description.

 

I understood, from something read on the Forum, that a loom with 4 wires is supplied as part of the conversion kit. I am at a loss as to why there should be 4 wires, since the alternator has, at most, 3 connections!

 

Ian Brown has purchased a kit from Revington, and tells me that Neil includes a copy of my article as the set of instructions (many moons ago, I told Neil he could do this). Not wishing to boast, I think one has a far greater chance of success using my article!

 

I'm not sure I can help further, unless you (or someone else) can provide a photo or sketch of the loom supplied by Moss (including wire colours and sizes) and any supplementary instructions indicating how the wires are to be used.

 

I am glad to see that Wykeham99 has solved his problem, but it should not be made so hard for purchasers to get it right - instructions should be clear and unambiguous. And if a purchaser gets it wrong and cooks his brand new alternator because the instructions are unclear, whose fault is it? In my book (and speaking as a Chartered Electrical Engineer), it's the fault of the supplier.

 

Ian Cornish

[littlejim]

Ian,

this what the back of the Moss alternator supplied for my 4A looks like.

It came with yellow/brown for the ignition light and a small brown and a thick brown joined together at a large ring connector as the only other wires.

The VTR article got me to run it(the browns) straight to the battery via the battery connection on the solenoid.

Obviously the ammeter couldn't show it charging the battery even though it was. (however, how was I to know that?)

After much study of everything I could find, I connected the two brown wires to the 'IN' side of the ammeter, which after some study I worked out was what the dynamo was connected to, despite the complexity of the voltage regulator.

I think what novices like me would like from experts like yourself is how to connect the alternator so that the original ammeter still works,(don't want to get a different one) and what we should do in the way of shunts to avoid burning the original ammeter out.

Suggestions on how to do the connections and shunts in a readily available spot rather than behind the instrument panel would be good. Apparently getting behind the instrument panel on earlier models is a breeze. Not so in the 4A.

Edited August 27, 2010 by littlejim

[Dave Larnder]

Hi Littlejim

 

"Have you fallen in the water recently?" or are you too young to have listened to the GOON SHOW in which littlejim was always falling in the water according to Spike Milligan ( after the sound of a large splash - of course). I bet Ian Cornish remembers him.

My alternator is the same as yours as shown in the picture with the same wiring and colours although my completely new loom was made by Autosparks and had nothing to do with Moss, I feel I must add. (This is why I think I have a redundant 4th wire.)I have done away with the regulator so I must connect direct to the ammeter as Ian suggested.

Did you see on "Your 4A forum" yesterday the reply from GT6 on the same subject?

[littlejim]

Hi Littlejim

 

"Have you fallen in the water recently?" or are you too young to have listened to the GOON SHOW in which littlejim was always falling in the water according to Spike Milligan ( after the sound of a large splash - of course). I bet Ian Cornish remembers him.

 

 

Egad my cover's blown. He's picked it like a dirty nose.

Simon jrwinter can I borrow your pseudonym now please?

[ianc]

Just to say that I have written a description which should explain the mysteries surrounding the alternator kit supplied by Moss. This is being "road-tested" by a couple of guinea pigs (sorry, fellows!) and should be ready for publication in the near future!

The bad news is that, with diagrams included, it runs to four pages!

Watch this space.

Ian Cornish