Voltage Regulator Problem
Posted: 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!
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!