Charging problem

[Alan Hawley]

I am just starting my TR4A after a major rebuild I turn key ignition light comes on.Start engine light stays on and no charge on ammeter.Rev the engine light is very bright and then blows.Have confirmed Dynamo is putting out and fitted new voltage regulator.Checked all connections.Is it possible the ammeter wiring needs switching around.Any ideas? Alan

[boxofbits]

1 hour ago, Alan Hawley said:

I am just starting my TR4A after a major rebuild I turn key ignition light comes on.Start engine light stays on and no charge on ammeter.Rev the engine light is very bright and then blows.Have confirmed Dynamo is putting out and fitted new voltage regulator.Checked all connections.Is it possible the ammeter wiring needs switching around.Any ideas? Alan

 

Hi Alan

I had a similar problem on another car with the same set up. Best to check the output of your dynamo/ regulator at the battery connections with a meter. Something like 12.8 volts should be normal, but you might find your new regulator is not adjusted properly or is faulty with the contacts of the armature staying open. You’ve got no charge on start up hence ammeter not moving and light staying on. As soon as you rev your voltage is far too high and blowing the bulb. Does the ammeter needle move when the light goes out? There is a section on regulator adjustment in the w/S manual

Kevin

Edited March 14, 2020 by boxofbits

[Alan Hawley]

The ammeter goes negative when car not running and lights on The regulator is new and replaces a new one so I have eliminated this component as the problem.Dynamo is obviously working.Could I have 2 duff regulators? Alan

[Lebro]

Sounds more like a wiring problem to me. with engine running above  say 1000 revs the dynamo output is connected to the battery (via the ammeter) and as that is also where the ignition warning light is connected to (via the ignition switch) then the bulb should go out. if it gets brighter, then it is wired to the wrong place.

Bob.

[Alan Hawley]

Lebro thanks for your reply Do you think I should change the connections to the ammeter ? Alan.

[RobH]

The ammeter polarity sounds fine to me if it shows a drain with the engine not running and the lights on. That means it is the right way round and that the loads are connected to the right end of it which also means the ammeter must be connected to the right place on the regulator.

I agree with Bob that the problem sounds like a wiring fault and Kevin has a good point too. If the connections to the regulator are wrong the dynamo output may be far too high but that should be reflected by a very high charge current shown on the ammeter. As it isn't it suggests a wiring problem - possibly that there is no earth on the E terminal of the regulator. 

Can you clarify a couple of points  please? After starting you say the ignition bulb does not go out but just gets brighter with revs. Are you sure it does not go dim as the revs rise a bit and then get brighter again as they rise further?

If you have the headlights on with the engine running do the lights get very bright with increased revs?

 

[Alan Hawley]

Rob on tick over the ignition light flickers.With increased revs it goes brighter.With headlights on no change in brightness as the revs rise.The earth wire is connected and I have checked there is power at the wire.Blew another ignition bulb.For me it points at another dud regulator.Could the Voltage stabiliser in the foot well be at fault? Alan.

[Lebro]

Just to clarify, the ignition warning light should not have an earth connection, one side connects to the ignition switch, & the other to the "D" connection of the regulator (which is also connected to the main output of the dynamo). The voltage stabilise is nothing to do with your problem.

I would check all the wiring around the voltage regulator, including a good earth connection on the "E" terminal.

Bob.

[RobH]

If you are sure the connections are all correct it does sound as though the regulator is not working.  Certainly the cut-out contact is not closing else you would see a charge (possibly a very large one) on the ammeter and the headlight brightness would change with revs..  That is probably a good thing as the excessive current might damage both the ammeter and the battery.  

It seems the dynamo field current may be at maximum all the time. It is supposed to be controlled by a rapidly-cycling contact inside the regulator so that the voltage at F is turned on and off many times per second. As the dynamo output rises the on and off times of the contact vary to reduce the field current and so regulate the output. It seems that may not be happening in your case - perhaps the contact is permanently closed. It is important that the regulator is properly earthed at E as without that connection this regulation function will not work.

A simple but not very helpful test would be to pull the brown/green wire off the F terminal. That should stop the dynamo from generating and would prove that the excess field current is coming from the regulator and not from some short circuit in the wiring.

There have been cases recently where duff regulators have been supplied - if I remember correctly that was poor materials in the contacts - so it is possible this is more of the same or perhaps supplied in unadjusted condition to save on costs?

( A word of warning at this point - unless you know what you are doing it is not advisable to fiddle with the regulator innards other perhaps than to carefully clean the contacts. If you feel confident and have the kit, this link tells you how to check and adjust:

.https://mgaguru.com/mgtech/books/pdf/Lucas_Generator_and_Control_Box_Tests.pdf.    )

 

Edited March 15, 2020 by RobH

[Lebro]

1 hour ago, RobH said:

If you are sure the connections are all correct it does sound as though the regulator is not working.  Certainly the cut-out contact is not closing else you would see a charge (possibly a very large one) on the ammeter and the headlight brightness would change with revs..  

Also, if cut-out contact was closing the warning light should go out.

Bob

[Alan Hawley]

Rob the large wire to the dynamo is Brown The large wires to the regulator are A1Brown/Blue A is Brown/White and D is Brown/Yellow. All as the wiring diagram.I really don’t understand how the regulator works but is it possible when this new loom was built A and D were switched.Would I cause damage if I changed them over.I am grasping at straws now!! Alan.

[Lebro]

Large (charging) wire from dynamo should be Brown/Yellow to "D"

Smaller (field) wire from dynamo should be Brown/Green & goes to "F"

Black (earth) wire goes to "E"

Brown/White joins ammeter to "A"

Brown/Blue joins ign & lighting switches to "A1"

I would check all these are going to the right places.

Bob.

Edited March 15, 2020 by Lebro

[RobH]

+1 for Bob's post. Don't just swap anything around - check they go to the right places.

I take it the large brown wire from the dynamo goes to the D terminal on the regulator, as does a smaller brown/yellow wire which goes to the ignition lamp ?  

The brown/green wire from the F terminal should go to the small terminal on the dynamo which is the field connection. There should be nothing else connected to those terminals.

If all the connections check out OK it must be the regulator at fault.

[Alan Hawley]

I decided to dig out the original regulator from my scrap box,covered in red paint Connected it and works perfect.So that’s 2 defective regulators.Any suggestions where to go for another new one.Thanks for all your help and suggestions Alan

[Lebro]

http://www.dynamoregulatorconversions.com/reproduction-rb106-and-rf95-regulators.php

Modern electronic version, works very well. need to state ve or -ve earth

No connection, but have installed a couple fro a friend.

Bob.

[Gary Flinn]

21 hours ago, Lebro said:

http://www.dynamoregulatorconversions.com/reproduction-rb106-and-rf95-regulators.php

Modern electronic version, works very well. need to state ve or -ve earth

No connection, but have installed a couple fro a friend.

Bob.

Bob

I'm seriously considering getting one of the Electronic Regulator off this company for my current Classic, have the ones you have fitted been reliable?

Gary

[Andy Moltu]

Fit an alternator and ditch the regulator altogether?

[NickKerfoot]

I have one of there regulators on my S1 Land Rover. The ignition light once out, stays out - you don't seen to get the normal dull glow or flicker at very low engine rpms. Completely reliable over the 3 years it's been fitted...

[Gary Flinn]

17 hours ago, Andy Moltu said:

Fit an alternator and ditch the regulator altogether?

I had considered that, but I believe a special Alternator specific mounting bracket is needed for my particular car and is not easy to find, plus of course there's the cost of the Alternator too?

I've also recently had the Dynamo fully reconditioned!

According to the website the Electronic Regulator makes the Dynamo more efficient, although I know it will never be as efficient as an alternator.

I've also considered one of the US Manufactured Powermaster look a like Dynamo's (that is actually a 90 Amp rated Alternator) but have had a quote off a specialist and its a ridiculous price (£500+)     

Gary

Edited March 17, 2020 by Gary Flinn

[RobH]

21 minutes ago, Gary Flinn said:

According to the website the Electronic Regulator makes the Dynamo more efficient,

A physical impossibility I'm afraid. All it can do is regulate the voltage with better accuracy, it will make no difference to the amount of charge the dynamo can produce since that is determined by the windings in the dynamo and the speed of rotation.  The problems with a dynamo are the need for high current to go through the brushes and commutator, and the mass and construction of the armature which limits the speed it can rotate at without flying apart. In order to prevent that the pulley is sized so it cannot over-rev but that means it doesn't rotate fast enough at low speeds to give a decent charge.

The moving part in an alternator is smaller and lighter meaning it can safely spin faster allowing a smaller pulley to be used, so that useful charge can be produced at low revs. The high current part is static removing the limitation of the commutator too.

There are mixed reports of the alternator-in-a-dynamo-case devices. Some seem to fail due to overheating because the ventilation is poor compared with the more open construction of a standard alternator.

 

[tthomson]

On 3/15/2020 at 5:08 PM, Alan Hawley said:

I decided to dig out the original regulator from my scrap box,covered in red paint Connected it and works perfect.So that’s 2 defective regulators.Any suggestions where to go for another new one.Thanks for all your help and suggestions Alan

Hi Alan,

Regulators are not as generic as one might think. They are often model specific.

A brand new twin coil regulator is not likely to work properly straight out of the box. You need to make sure both the cutout and voltage regulation contacts are setup correctly.

To me, your problem sounds like the voltage regulation side of the regulator is not pulling in at a low enough voltage, which means the dynamo is able to generate too high an output voltage as its revs increase,  hence blowing the bulb.

The regulator needs to be setup in the correct order. Cutout first and then the voltage regulator.

You will need to have a decent analogue voltmeter to do it properly.

Modern electronics are incredibly reliable and robust, and I would go with an electronic version. Others might prefer to remain original, and in which case the regulator is the way to go. Once properly setup, the regulator will perform well for years.

Good luck in whatever you choose.

TT