Did you check to connections on the starter switch are clean? The battery charges back thru one side of it. The side with two wires.

Side question:

When you polarize a part, does it always stay polarized? Or do you have to re-polarize when the battery is disconnected?

Thanks!

My Interstate battery (~10 months old) was bad.  I just swapped it out for its replacement.

I've cleaned the contacts on the inside and the outside of the new voltage regulator.  Zero corrosion, and no chance of any residue still.

I've polarized the generator by touching a wire from the negative/black battery terminal to the smaller connector of the generator.  Polarized the regulator by touching the rightmost connector ("E", with the largest coil of wires) to negative/black, just like the YouTube tractor video shows.

It still won't charge.  I'm stuck for clues.

I even tried the old regulator, cleaning it like new, inside and out, and it's not helping either.

Thanks,
Ryan

Well I've got my task for the evening.

As Dan said... clean the INSIDE contacts.  We are not talking about the wire terminals.  Hopefully that will resolve your car's charging problem and the red light will go out.

Did you clean the contacts INSIDE the voltage regulator? This video shows how to clean the contacts inside the regulator. Note it is different from your regulator but the inside components are very similar and the cleaning concept is the same. In this video, he is rejuvenating an old regulator where the contacts have corroded and worn with age.

https://www.youtube.com/watch?v=M9G2qe7Pd60

I cleaned the voltage regulator leads twice with acetone.  I tested each lead with my multimeter, and it's conductive.  I also saw that a few wires are corroding, so I took a little sandpaper to the terminals.

I got the generator to spark -- the problem was that I connected the alligator clip to the positive/red terminal of the battery.  When I switched to negative/black terminal and touched the generator's lead, it sparked.

I tried starting the car, it took a solid 30 seconds of attempts (something it's never needed before), and the engine started, but the IGN light is still on.

Also, some time in the last day, I blew my last fuse.  Going to put an order in right now for more.

Any ideas?

Thanks,
Ryan

Try Doug Lawson's advice about cleaning the contacts inside the  new voltage regulator you have. If that doesn't work, try putting the old one back in. Make sure the wire connections to the voltage regulator are correct, clean and tight.

I tried polarizing the generator during the week, but my battery had died again.  I picked up a trickle charger (there's a good sale at AutoZone right now!).  The battery's fully charged, and I can start her up from the push button, no problem.

Here were my steps trying to polarize the generator (please note: I'm new to car electricals):

* I turned off the car
* disconnected the wire from the smaller lead of the generator that runs between it and the voltage regulator
* took a good, long length of 14ga wire (it's the thickest I've got); attached alligator clips to the ends
* tested with my multimeter that there's no break in the wire from clip-end to clip-end
* attached one of the alligator clips to the positive/red terminal of the battery
* touched the smaller lead of the generator with the other clip

...no spark.

* clipped on to the smaller lead of the generator

...still no spark.

* disconnected the wire from the generator, then the battery
* turned the car on

... IGN light's still on.

Where am I going wrong?

Thanks,
Ryan

Did you open the new control box and clean its relay contacts?  That is a MUST on the current replacement control boxes.  They are shipped with a Cosmoline-like coating on the contacts to prevent their corroding while in storage.  That coating is an electrical insulator.  Use acetone on a rag dragged through the contacts to remove the coating.  Do this several times to make sure you have removed all the coating.  Failure to remove the coating means there is a good chance the regulator will never work.  

Zoom in on the picture shown in the link below.  You'll see there is a warning label about cleaning the contacts.
https://www.bpnorthwest.com/voltage-regulator-lucas-mga-tr3-tr4-tr4a-plug-in-style.html

Also see the link below for an electronic voltage regulator that is available.  Unfortunately I have only seen these available with screw terminals... no spade lugs.  To use it you would need to modify your car's wiring harness to remove the female spade terminals or you would have to buy some form of male terminal and modify them to fit the screw terminals on this regulator.
https://www.bpnorthwest.com/voltage-regulator-digital-lucas-screw-in-terminal.html

If your iginition light stays lit when running, it's an indicator that your battery is not charging.   Check your fan belt and make sure you don't have more than a small deflection in the longest run of the belt between pulleys.  Also go to the boot and remove the short ground cable from the battery and the body.  Clean the ground cable end and the metal where that cable is bolted to the body. When you reinstall it, use a star washer so that it 'bites' into the boot floor pan.  Most electrical problems start with bad grounding of the circuits. Black wires on the mini are ground wires.  Do you have a Haynes workshop manual yet?  If not, buy one for your year car.  It will not only have an electrical schematic, but give you all the procedures for making repairs to your car. And there's usually a section for troubleshooting.  Worth the few dollars.

Yeah, the voltage regulator is brand new.

You said the generator was new.  Is the generator control box also new?

The battery may still not be up to snuff. A 12V battery has 6 cells, each of which produces 2.2 volts when good. 6 x 2.2 = 13.2V. Depending on how Autozone tested it it may be OK - if load-tested the voltage reading would be slightly lower. If it is just a straight voltage meter reading, I'd still be suspicious of it.
As I said before, and as concurred by onetim the charging voltage needs to be higher than the battery voltage to recharge it. But not too much or the battery will be cooked! One symptom of excess charging voltage is a suphurous or rotten egg smell from the battery.

Glad your back up and running. Thanks for the update.

Hey Ryan, you should see a voltage rise across the battery running verses not. if the battery voltage is the same running or lower as when the engine is stopped, it's not charging. Usually this is a couple 3 volts variation at the most. 

Evening everyone,

I took the battery in for a 10-hour trickle charge at the shop I bought it from (the shop owner asked to do this before replacing it outright).  On my way home, I stopped by AutoZone and asked them to check the battery out.  It got a clean bill of health, running 12.8 volts with a full charge.

I installed it, and my Mini started up!

My IGN light is on constantly, so I need to read through the forums to start working on that problem.

Thank you all for your help!
Ryan

I just watched the YouTube video, and I accidentally did that yesterday before posting the thread, and yep, I got that small spark.

Battery update:

Went back to AutoZone to pick it up. They said my 10 month old Interstate battery's bad.  They tested it again in front of me, and sure enough, "bad battery" on the readout.  So I'm hoping the shop I picked it up at is open tomorrow on Presidents' Day.

I'll let you all know when I put the replacement in.

Have a good weekend & thanks so far!

Ryan

Since it is a new generator, is it polarized correctly to match how your car was polarized when everything was previously working?

https://www.youtube.com/watch?v=NV8FFgia7uU