Sounds like a ground problem to me. High resistance causing excessive output and overheating the VR trying to control it?

It's my collection of oddities that is puzzling me. Why would the tach be erratic and read a higher RPM? Why would the VR(s) keep getting overheated? They aren't ALL bad and I've been dialing them in before long trips.

Since my car is SOOOO original I'm trying my best to keep it that way. I have a source for a Fiesta Alt but really only want to do it as a last resort. I have in my possession 3 VRs and at least two generators.

I suspect the current (HA) problem is related to the brushes. Though I just put a set in, I wonder if one of them isn't working right only giving me a partial voltage.

I checked the points gap on my distributor and it's fine. Recently I had issues as the block had worn down and the points gap was reduced to almost nothing.

Please keep this thread open with ideas. Yes, I know it's british and Yes, I want to keep it alive for another 50 years.

A thorough inspection of all parts of this system will ultimately sort the problem.

All wire terminals at the ignition switch, charge warning lamp, generator, solenoid and control box need to be correct. The ignition switch could also be a failure point. The engine or battery to body ground strap could be the culprit. A poorly positioned clamp on the exhaust could be causing an intermittent short to the main power cable.

A bit of work is what is required. 

This is absolutely no place for Lucas jokes or defeatist comments about minis being unreliable like Rob/Specialist repeatedly posts.

Your mini is, I think, quite nice, and I can see a desire to keep it as original as possible. Personally, I would fit an alternator after the things I listed have all been checked and corrected. An alternator will be able to power decent headlamps with halogen bulbs, via a pair of relays; and improve your driving experience.

The original voltage regulator as mounted in the MK1 engine bay is a fairly simple device. It uses coils to open and close points to control voltage as supplied from the generator(dynamo ). Like the points in the distributor, they need to be maintained, but are east to clean and polish with crocus paper. Very slightly convex and mirror finish. Then you need to check the point gap. Assuming the coils have not been cooked, you need only a voltmeter and screwdriver to adjust the voltage output.

Here's a link to a series of short (less than 2 minute) Youtube videos by Moss motors to get you started.

Moss Motors Videos

It doesnt matter if you buy used or spanking brand new VR if you have electrical issues somewhere, it will fry no matter what.. I have faced few issues on my mini, i seek help from mr Haynes but he failed to give me a solution so i used my common sense instead.  My theory in life is: Man created minis, man breaks minis, Only man can fiix the minis. You have six senses, use them.  Pretty blunt, but at the end, i know you'lll thank me.

They also sell an alternator that looks like a dynamo/generator, not cheap but has the look of vintage.

You bought used voltage regulators off Ebay and hoped they would fix the problems...and they did not. Yeah. Look, the original Lucas regulators worked OK but now they are 50-60 years old, well beyond the life expectancy. They were manufactured with rivets through some kind of insulating plastic, and heat and vibration and corrosion means those connections are no good now; they become resistive or open circuits. The resistive ones get hot, melt the plastic, get hotter, then open. I could suggest you find one of those DIY sites on fixing vintage regulators, but testing a VR and proving that it works requires a bench full of electrical test gear, so I think in your case its time to spend a few bucks. If you want to stay vintage, get the generator tested and if its OK then spring for a new regulator. If you don't mind a non-vintage look, upgrade to an alternator; the simplest installation leaves the electromechanical VR on the firewall, there are plenty of sites explaining how to do the new alternator to old VR wire connections; I bet our host has a tech article on it.

I know I know, there are books and articles and website FILLED with information how to fix your British car's electrical system. This one has me perplexed.

In short, (pun intended), I keep burning up voltage regulators. Luckily ebay has been kind and I keep finding them for $15 or so. My problem is I drive the car for a while, think I have it all in check, then all of a sudden my light comes on and my regulator has been very hot. So hot the plastic insulation around one of the coils is melted. I replace the VR then it seems to be fine. I chalk it up to either a maladjusted VR or a fluke and keep going. This time it's got me more confused. I drove for about 2 hours and my battery went completely dead. My lights were so dim they were yellow, then the car shut off. Dead battery. I swapped out the VR for a spare I had and it seemed OK for a while. When I got hear home again it was nearly completely malfunctioning. Here's the hitch, the tach is over reactive. At what should be 5k it reads anywhere from 7k to 8k. Looks cool, but it aint right. Recently the IGN light would stay on until high RPM. I pulled the Gen and found I dropped a brush. VOILA I bought another set and put it in. Bummer, the light still only goes out at high RPM, like reading 8k on the tach (BS). I put a meter on the large spade of the gen and it only gave me about 3v. I tried to polarize the gen but it made no difference.

1. Is my gen defunct? 2. Is my wiring defunct? 3. Are there adjustments to the system that are causing my VR to burn up?