This 1962 series 1 had been converted to Lucas alternator model 11ac, after market mechanical regulator, voltmeter and negative ground and has functioned well for several years. Last autumn after years of charging at over 17 V, I discovered the sealed battery was close to dry and around that time I noticed the voltmeter was showing under 12V. After replacing the battery and inspecting and adjusting the regulator , I have been unable to keep the battery charged because I am finding it impossible to get more than a 12V charging rate. Except on two occasions recently, once I had fully charged the battery with a trickle charger, then started the engine , I see the voltmeter reading 13+V for the first 15 minutes and then back below 12V.
Can anyone suggest a possible cause ,or method of testing to determine if the alternator is malfunctioning or other causes ?
The regulator is likely a dodge product and shown in an earlier post of mine,“alternator regulator charging problems”. On inspection it appear intact, and has two positions. Usually it has a set of points that connect the leads marked “field and ign” , then if the coil is energized by the voltage output, the points change and connect to a resistor that goes to ground. The adjustment is by changing the tension on the spring which will determine at what point the magnetism in the coil can switch from one position to the other. Testing it with a meter showed it is functional and worked for many years though it was not adjusted right to prevent overcharging. .
I adjusted it to make the air gap according the specs, but I believe the main purpose is to prevent overcharging, and I am now having insufficient charging with the points in either position.
I can’t speak to your Mopar regulator but will mention that for about 40 bucks you can get the regulator that Jaguar (and everybody else) was using back in the day and is known to play nice with the 11AC.
I would agree entirely with Geo’s statement - I was about to make a similar one myself. My only reservation now is that you may have toasted your alternator as well as your battery, so before I install the correct regulator I would have your alternator tested at your neighborhood FLAPS to make sure that it is still OK. Otherwise, you may end up in one of those cycles of “a bad x destroyed my y, which then destroyed my z, and blew up my new x…”
If I’m not mistaken, the Mopar regulator is B-circuit, meaning it controls field positive, whereas the Lucas regulator is A-circuit, and controls field negative. It shouldn’t matter because if you’re using an 11AC, the field is isolated. But it will cause confusion for any Jag tech who looks at the car in the future. The mopar regulator is adjusted by bending the contact arms. If this was done correctly, you would have been charging at 14V or so, just like any other alternator. Running at 17V is hard on the entire electrical system. The odds are, your alternator is toast. Hopefully that’s all.
I’m not sure if auto parts stores are set up to test externally regulated alternators, but it’s worth the effort to pull it and take it around. Someone will be able to test it. If not, you can jury rig a test by attaching a ground to one of the F terminals, and directly wiring 12V+ to the other. Run the engine for a few seconds. The charging rate should shoot to the moon, so be prepared to shut the engine down pronto. If it remains at 12 or 13V, your alternator is trashed. Don’t forget to remove the temporary leads immediately, or you’ll incinerate what’s left of the alternator.
I’d normalize the entire harness, using a Lucas regulator. It’s not necessarily better, but at least it will take the mystery out of it.
I just went through this. I took my 11AC to O’reilly, Autozone and Advance auto parts and none could check it. The chains are using a computerized machine and won’t know how to hook up any alternator that isn’t in the testing machine’s database.
You need an old fashioned automobile electrical shop or a generator/starter/alternator rebuilder to look at it. Check your yellow pages under “automobile electrical repair”.
I typically suggest the best place to check an alternator or generator is on the car, not off. Test it by exciting the fields as Michael says above. Typically just checking to see if it can it can reach 15/16 volts is enough, if you want to check further, test the amp output against specs. I doubt if 17 volts would hurt it, after all, it apparently output 17 volts for sometime. And, back years ago before converters, people used to hot wire the fields to output 110 volts to run drills out in the field, apparently with success. (I never did personally.)
Thanks for all the replies! Here’s is the latest update. I tested the system and found I was not getting a full 12V to the alternator at the input to the rotor. I spent hours replacing wires, connectors, polishing connections but couldn’t seem to increase the voltage. Eventually I ran hot 12V into the unit but got little more back when running. I removed the unit and began to look for an easily available substitute and at the same time read the manual for the AC11. They tell you have to disassemble the unit and suggest there is little servicing however they recommend cleaning the slip rings with a petrol soaked cloth. They don’t tell you how but despite this I decided to remove the plastic insulator housing by removing whatever screws, nuts ect. that seemed to hold it on. This housing held the brushes and exposed the slip rings. One brush was very short and the spring had disintegrated from rust, heat, age or corrosion. The manual says to test the resistance at the connectors, and it was very high, however resistance at the slip rings was pretty close to the proper spec of 3.8 ohm. Now I am looking for some replacement brushes locally before I have to mail order for them. Maybe this will solve the issue.
I got brushes and bearings from my local auto electrician - he had them in stock. All done for AUD$25 on a Friday afternoon. Left for Hobart, Tasmania on Sunday - about 2000km away. Paul
I normally used wet and dry paper then washed with Alcohol, lately I’ve been using Mylar cleaning strips from the dentist - the abrasive is non conducting, and the strips last longer in my toolbox.