Voltage regulator / Generator help needed : T-Series & Prewar Forum : The MG Experience

Voltage regulator / Generator help needed #1
Tim66 Tim Burchfield Columbus, OH, USA Sign in to contact 1951 MG TD 1953 MG TD 1953 MG TD 1960 Austin-Healey Sprite	Topic Creator (OP) Oct 27, 2016 04:20 PM Joined 14 years ago 3,242 Posts

In the early stage of checking the generator and voltage regulator, not wiring the car yet. I've connected the generator, fuel pump, coil, ground, ignition and ammeter to the regulator, no lights horn, ect. When I rev the engine the voltage going to the battery continues to climb up to 16 volts and higher at wot. That seems excessive to me. The second problem is when I turn on the ignition key the fuel pump starts and current flows to the coil but when I turn off the ignition the engine continues to run. I realize this could be a complicated problem but I thought someone might have a simple solution. Thanks

Tim
TD12524

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Re: Voltage regulator / Generator help needed #2
RichardM7908 Richard Michell Dee Why, NSW, Australia Sign in to contact	Oct 28, 2016 02:36 AM Joined 9 years ago 201 Posts

Re the continuing to run with the ignition switch off, do you have the ignition warning light wired into the circuit? If yes, is it the correct unit?

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Re: Voltage regulator / Generator help needed #3
Tim66 Tim Burchfield Columbus, OH, USA Sign in to contact 1951 MG TD 1953 MG TD 1953 MG TD 1960 Austin-Healey Sprite	Topic Creator (OP) Oct 28, 2016 06:24 AM Joined 14 years ago 3,242 Posts

Richard, no I do not. I'll do so this morning and see if it makes a difference.

Thanks

Tim

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Re: Voltage regulator / Generator help needed #4
RichardM7908 Richard Michell Dee Why, NSW, Australia Sign in to contact	Oct 28, 2016 06:59 AM Joined 9 years ago 201 Posts

I may be misdirecting you. It is possible, with the wrong resistance through that circuit, for the ignition to be kept active after the switch is off (AMHIK). But if you have no connection at all, that cannot be the feedback loop. Must be somewhere else in how you have connected things.

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Re: Voltage regulator / Generator help needed #5
Tim66 Tim Burchfield Columbus, OH, USA Sign in to contact 1951 MG TD 1953 MG TD 1953 MG TD 1960 Austin-Healey Sprite	Topic Creator (OP) Oct 28, 2016 08:48 AM Joined 14 years ago 3,242 Posts

Richard, I believe the resistance issue was the cause. I installed the GEN warning light and the engine now shuts off with the key. Thanks for the suggestions.

Regards

Tim
TD12524

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Re: Voltage regulator / Generator help needed #6
Robert H Robert Harvey Wichita, KS, USA Sign in to contact 1951 MG TD "Millicent Grace (Millie)"	Oct 28, 2016 04:27 PM Joined 10 years ago 773 Posts

If you are still getting the 16V at the battery, that sounds like an issue of mal-adjusted regulator. The workshop manual has a decent section on how to adjust this. I have had better luck with old analog voltmeters for this job, as the regulator essentially just chatters, connecting and disconnecting the generator to the battery to provide an "average" correct voltage. The chatter seems to confuse my digital meters.

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Re: Voltage regulator / Generator help needed #7
Tim66 Tim Burchfield Columbus, OH, USA Sign in to contact 1951 MG TD 1953 MG TD 1953 MG TD 1960 Austin-Healey Sprite	Topic Creator (OP) Oct 28, 2016 04:42 PM Joined 14 years ago 3,242 Posts

In reply to # 3383319 by Robert H If you are still getting the 16V at the battery, that sounds like an issue of mal-adjusted regulator. The workshop manual has a decent section on how to adjust this. I have had better luck with old analog voltmeters for this job, as the regulator essentially just chatters, connecting and disconnecting the generator to the battery to provide an "average" correct voltage. The chatter seems to confuse my digital meters.

Robert, I adjusted my regulator using the workshop manual and now max out at 15.5 volts. Amazing how much you learn from problems rather than successes.

Tim

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Re: Voltage regulator / Generator help needed #8
Robocam Blair Robson Auckland, Epsom, New Zealand Sign in to contact 1978 Ford Escort MkII	Oct 30, 2016 07:35 PM Joined 13 years ago 33 Posts

Hi Guys
Both TD & TF use LUCAS compensated voltage regulators The correct way to set these is to disconnect the regulator from the the battery and set the correct 16v voltage on open circuit
This usually achieved by placing an insulated material between the cutout contacts so that as the voltage rises it will not connect to the battery. The voltage can then be set to the correct 16V open circuit.
This assumes that the regulator in in good condition. When any load is drawn from the electrical system the regulator automatically adjusts out put to protect the generator.
Hope this helps
Blair

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Re: Voltage regulator / Generator help needed #9
RichardM7908 Richard Michell Dee Why, NSW, Australia Sign in to contact	Oct 30, 2016 08:54 PM Joined 9 years ago 201 Posts

Further to what Blair says, attached are some test instructions from Lucas. Compensated voltage regulator starts on P.5.

Lucas_Generator_and_Control_Box_Tests.pdf 1.06 MB

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Re: Voltage regulator / Generator help needed #10
Sarastro Steve Maas Long Beach, CA, USA Sign in to contact 1952 MG TD 1966 Triumph TR4A	Oct 31, 2016 11:05 PM Top Contributor Joined 11 years ago 274 Posts

The high system voltage is almost certainly caused by a bad voltage regulator--the regulator relay seems not to be working.

As for the car continuing to run when the ignition is turned off--have you added a relay for the power switched by the ignition switch? If so, the relay coil is staying energized by the generator, via the ignition lamp. If not, the ignition still could be powered through the lamp, but it seems unlikely. You'd have to have an incorrect bulb, one rated for much higher power than the correct one. Are you sure that power is being turned off at the ignition coil when you turn off the ignition? It might be just that simple.

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Re: Voltage regulator / Generator help needed #11
Tim66 Tim Burchfield Columbus, OH, USA Sign in to contact 1951 MG TD 1953 MG TD 1953 MG TD 1960 Austin-Healey Sprite	Topic Creator (OP) Nov 1, 2016 12:30 AM Joined 14 years ago 3,242 Posts

In reply to # 3385446 by Sarastro The high system voltage is almost certainly caused by a bad voltage regulator--the regulator relay seems not to be working.

As for the car continuing to run when the ignition is turned off--have you added a relay for the power switched by the ignition switch? If so, the relay coil is staying energized by the generator, via the ignition lamp. If not, the ignition still could be powered through the lamp, but it seems unlikely. You'd have to have an incorrect bulb, one rated for much higher power than the correct one. Are you sure that power is being turned off at the ignition coil when you turn off the ignition? It might be just that simple.

Steve, thanks for the input. I adjusted the regulator per the manual and the voltage is fine now. I added the ignition warning light to the circuit and the engine now shuts of with the ignition switch.

Tim
TD12524

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Re: Voltage regulator / Generator help needed #12
Robocam Blair Robson Auckland, Epsom, New Zealand Sign in to contact 1978 Ford Escort MkII	Nov 1, 2016 05:08 PM Joined 13 years ago 33 Posts

Hi Richard
It is terrific to see the old Lucas test manuals they are worth their weight in gold for identifying checking and adjusting all the 2 & 3 bobbin Regs which are in my opinion a very reliable and simple systems These pamphlets and data were only given to Authorized agents here and if you were lucky a Lucas rep would manage to get you the odd extra tech info if not available by OEM w/shop manuals. Good to see this is available for all to have access to
Cheers

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