Voltage Regulator Problem

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Belmont
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Voltage Regulator Problem

Postby Belmont » Tue May 14, 2019 10:34 pm

Hello! Sorry for the wall of text!

I bought my first Minor (a 1959 two-door saloon) a couple of weeks ago. The previous owner bought in in 1984 and restored it to a nice original condition. He did not drive it very frequently though, so I was a bit nervous when I drove it home, about 50 miles through the Swedish countryside. Luckily enough it worked out very well and we had no issues during the trip.

The first problem appeared when I tried to start it again a few hours after arriving back home -when I pulled the starter it only cranked a couple of times, then nothing. I then checked the battery voltage which was ~11,5 volts, well drained. I did not notice whether the "ignition warning light" was glowing or not on the way home, being new to Minors, but I did drive with headlights and heater turned on. After charging the battery on the bench for a couple of hours the car started and ran well again.

Car electrics isn't my strongest subject, but I suspected an issue with the charging and started to read up on it here on these forums and through other online resources.

The last week I've been doing some diagnostics and was making progress, until today when I got stuck trying to figure out the regulator.
The car has an original dynamo and (as far as I can tell) matching voltage regulator. Positive earth.
Tests and results up until now:
-"Ignition warning light" glows faintly at idle but goes out at ~1000-1500 rpm. With headlights it also glows very faintly at normal engine speeds.
-Fan belt tension is correct, roughly ½ inch of slack.
-Battery voltage at idle is (after charging on the bench) ca 12,45 volts, increasing slightly to >12,5 volts with the throttle half open. Not very impressive.
-The dynamo generates about 2 volts measured between the D-terminal and earth with D -and F cables disconnected. Within spec according to the Lucas fault diagnosis manual.
-When connecting D and F terminals on the dynamo and measuring voltage to earth it easily generates 15-20 volts. Going by the workshop manual this seems ok.
-I also tried running the dynamo as a motor by connecting D and F to the negative pole on the battery, and it spun quite fast without hesitation. From this, and the above, I gather that the dynamo is probably working correctly?
-The wires (D and F + connections at the regulator) also seem fine, and I get the same readings on dynamo voltage when measuring through the leads.

Here comes the problematic part, diagnosing the Voltage Regulator. I have tried reading through a lot of old posts here and comparing pictures of diffrent regulators, but to no avail.
Here is a link to a picture of my regulator, without the cover. http://forumbilder.se/I5CSV/voltage-regulator

I did get some part of the way diagnosing and adjusting the Regulator:
-I tried "Test 6 Open-Circuit Voltage Setting" in the Lucas manual. Connecting A1 and A leads and measuring between D and earth gave 12,5 volts. Unfortunately I found the instructions on adjusting the screw on the regulator frame unclear. Comparing with the workshop manual didn't help since my regulator didn't match the sketch there. I figured that "A" (see picture in link) was probably the correct screw, and upon turning it ½ turn clockwise I did get close to the specified reading at 16 volts!
-Thinking I was close to solving the problem I went on and checked the Cutting in voltage. Here I got reading of up to 16 volts before it "kicked back" and settled at ~15 volts. I figured that "B" (see picture in link) was probablt the cut-out adjusting screw, but turning this had no effect on my readings.

Finally I checked the battery voltage after my adjustments and got ~12,9 volts at a fast idle, climbing to >14 volts with slight throttle. Figuring that the cut-out wasn't working correcly and that I was probably over-charing I quickly switched off and disconnected the battery.

That's where I'm at.
I would be most grateful for some directions on where to go from here!

**TLDR: I suspect some fault in the regulator, specifically the cut-out points and need help from there**
-Should I do further tests/Have I done something wrong?
-How should I go about adjusting the regulator?
-I am unsure about testing the cutting in and out voltage, is there a better way to do this that described in the Lucas manual?

Thank you for reading!

oliver90owner
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Re: Voltage Regulator Problem

Postby oliver90owner » Tue May 14, 2019 11:58 pm

The battery should be charging close to 14.4 volts - depending on what type of lead/acid battery is fitted - at normal driving speeds in top gear. A dynamo, in winter with all ancillaries switched on may only just keep up with the loads, but if only using the dipped beam plus side lights, it should be OK.

Are you sure the drive belt is good? It should not be touching the bottom of any pulley, or may not drive adequately even if supposedly adjusted to the right tension.

If the voltage control proves faulty, it may be advantageous to invest in an alternator conversion, considering your location. Poor winter charging can affect the battery life, as well as making motoring more difficult. Personally, I would only retain a dynamo if originality was important.

Belmont
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Re: Voltage Regulator Problem

Postby Belmont » Wed May 15, 2019 5:44 am

Thanks for your answer.

I think I over-reacted when I saw the marked increase in voltage (as mentioned I only got 12,5 max before). Probably it was OK, I can test how high it goes under a little more revs next time, what should be the maximum battery voltage during charging?

I do think the dynamo and belt are both good. Especially since I got normal readings when testing the open circuit voltage.

What has me worried is that I do not know how to make certain that the cut-out points works correctly. Can anyone take me through how to reliably check that they work and how to adjust the regulator if need be?

Thanks for the dynamo tip. I will only be using the car during summer for leisure driving, and I quite like as much originality as possbile :)

Nickol
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Re: Voltage Regulator Problem

Postby Nickol » Wed May 15, 2019 10:24 am

Hej Bemont!

From your description, despite the rusty looking pieces, all is working correctly with your voltage Regulator but probably your battery is not in the best condition. Even new ones, which are not used regularly and charged , will deteriorate in only two to three years. Less if stored in a low state of Charge. Thus every time the car is not used for a time, the battery does not have enough "umph", especially with the choke in Operation to both turn the engine over and give sufficient spark at the plugs.

You can check without instruments by simply observing when the Points in the voltage Regulator open and Close. At tickover they will be closed but as soon as you rev the engine a bit, they should Close. I note that you did check Output from the Dynamo both at the Dynamo itself and at the voltage Regulator -i.e the F and D wires are performing OK. That was my Problem a few years ago.

There is a comprehensive Lucas fault finding/check listing available on the Internet. I will find it and post after this.
Gott schütze mich vorm Sturm und Wind und Autos, die aus England sind.
download/file.php?id=4822[/sig]

Nickol
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Re: Voltage Regulator Problem

Postby Nickol » Wed May 15, 2019 10:26 am

This is (one of ) the link Imentioned - much better than my description.

mk1-performance-conversions.co.uk/lucas-faults.pdf
Gott schütze mich vorm Sturm und Wind und Autos, die aus England sind.
download/file.php?id=4822[/sig]

JOWETTJAVELIN
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Re: Voltage Regulator Problem

Postby JOWETTJAVELIN » Wed May 15, 2019 6:17 pm

The warning light is your guide to the cut out performing, if you blip the throttle at idle it should go out. It is normal for the lamp to glow at engine idle. Forget an alternator, a dynamo is fine, you just need to measure the battery voltage with the headlights on and engine running fast enough to be charging the battery, around 14v. Make sure you do this test after a few miles running, the reason being there is a high initial charge rate immediately after using the starter.
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Belmont
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Re: Voltage Regulator Problem

Postby Belmont » Wed May 15, 2019 8:07 pm

Thank you Nickol and Jowett for your answers!

I will make sure to take a closer look at the battery, I do not know how old it is or how well it keeps its charge. Did check that the fluid level is good though.

I think I have misunderstod some of the functions in the control box/voltage regulator. Did some reading up on this site: https://www.morrisminorvic.org.au/Techn ... ltage.html
Also found that Moss Motors have some great instructional and educational videos on youtube about electrics.

Will get back to the car on friday and re-check the battery voltage under load, according to your advice Jowett, and take a closer look at the cut-out points now that I know how they should work.

Error in my OP:
For anyone looking at the picture of my regulator I now have figured out that the "A"- screw is for adjusting the gap in the regulator contact (which should be 0,012-0,020" according to the workshop manual). I guess mine must have been out of spec, since tightening it got my dynamo charging! (dumb luck...) "B" is for setting the cut-out point voltage, and the unlabeled screw to the left is for setting the regulator voltage.

oliver90owner
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Re: Voltage Regulator Problem

Postby oliver90owner » Wed May 15, 2019 10:39 pm

Lead acid batteries need to be kept in a fully charged state. If they are not, the plates will start to ‘sulphate’ and be difficult to fully charge - likely for ever. On the other side, overcharging electrolyses the water in the battery, produdcing a very explosive mixture of hydrogen and oxygen. Your battery, as you can add distilled water to replace any water losses by overcharging, is OK (up to a point, of course). If a sealed (maintenance-free) battery is fitted, overcharging will soon destroy it. The optimum charging voltage for a flooded lead acid battery is 14.4V. Nothing more and not much less!

JOWETTJAVELIN
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Re: Voltage Regulator Problem

Postby JOWETTJAVELIN » Thu May 16, 2019 3:06 pm

You're welcome, just keep things simple and don't get bogged down in the science. Let us know how you get on.
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