TR2/3/3A no leaks, but the generator is not charging

[CJD]

Something to mention...15-16.4v will work for very short trips, but that will boil the water out of your battery if you take it on any longer trips with that much voltage. I shoot for 13.5-14.4 for general driving with plenty of charge and little chance of over-charging.

It sounds like the problem all along was the cutout sticking open.

 

[TR3driver]

The problem is that this regulator does not regulate voltage and current separately; but rather the sum of voltage and current. Evidently a cost-saving measure on someone's part; other Triumphs got a 3-bobbin control box (with separate relays for voltage and current) but not the TR2-4A.

So the roughly 16 volts given in the book(s) is an open-circuit measurement, with no current at all flowing through the current regulation winding. Once there is some current output (to run the ignition and so on), the regulated voltage will drop. Add more load (like headlights) and it will drop even farther. This is from an article by Dr. Hugo Holden :

To me, it makes sense to make the adjustment with no current (a bit of paper stuck in the cutout contacts), since otherwise it is difficult to know what the correct adjustment is. But, the voltage you adjust is not the same as what the battery sees under normal conditions.

And if you set it to 14.4 volts open circuit, it won't charge the battery with the headlights on. Even the 13.2 volts given by Dr Holden above (for a 16v setting with full 22 amps output) isn't enough to fully charge the battery.

 

[CJD]

My bad...didn't know we were talking open circuit voltage. I shoot for the 13.5-14.4v measured at the battery posts with engine running above 2k and no other loads. That's how I normally run the car. If I were normally running with lights and heater, I would still set the same voltage low end (13.5v), but would do it with those accessories running during the adjustment.

 

[TR3driver]

I'm just trying to explain why the book says what it says. With your method, John, you are relying on the battery to be fully charged, so it takes little or no current at 14v. If it were partially discharged and taking significant charging current while you were checking the voltage, you could wind up with the regulator set too hot.

And the hidden gotcha here is that protecting the generator from putting out too much current is at least as important as protecting the battery from too much voltage. The battery will put up with being overcharged a lot longer than the generator will put up with too much current!

Long time ago (back in college), I was spending most of my disposable income on rebuilt generators, before finally learning that lesson. A dead battery is a lot better than a burned up generator! Of course, back then, I didn't have a workshop manual, nor the electrical training I eventually got in college. Someone told me I could have fewer dead batteries if I turned the voltage regulator up a bit, so that's what I did.

 

[CJD]

Yes, My batteries are always fully charged when I work on my cars. Every manual I have ever worked with starts with "ensure battery is fully charged". In my experience a car's battery is just like Momma...So long as Momma's happy, everyone is happy! And since V=IR, voltage and current correlate directly. Keep one under control and the other inevitably follows. Likewise, a problem with one will reflect with the other.

 

[TR3driver]

Yes, My batteries are always fully charged when I work on my cars. Every manual I have ever worked with starts with "ensure battery is fully charged".

The TR2-3 factory workshop manual doesn't say that ...