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MG MGA - Generator Charging Rate

Re: 1961 MGA
At high rev, my generator is charging as high as 16.1 volts. Is this safe for 12 V battery I am using? If not, is it caused by a faulty voltage regulator or faulty generator? Do I need to purchase a new stock regulator or a new solid state regulator or can the old one be adjusted with ease.
Thanks,
Eddie
E.W. Haynes

Hi Eddie
16V is a bit too high, you need to be down around 14 max.
If your generator is poking out good voltage like that it's fine-----it's needing the regulator adjusting
You can adjust the voltage regulator quite easily,
connect a good well known voltmeter and looking at the regulator from the side where the wiring attaches, remove the cover and down over the back face of the left side coil you'll see an adjusting screw (horizontal screw) usually these are painted yellow--screw it in for more voltage or out for less-
The electronic regulators run at 14.4V which is at the top end of specs, I'd use that voltage as an absolute max. but probably aim more for around 14

I'll see if i can find a vid. of it

willy
William Revit

Eddie
Here you go -----

https://www.youtube.com/watch?v=kxK4GaK1wNg
William Revit

Interesting Willy. I learned something today from that video.

Steve
Steve Gyles

Thanks for your comments and video. To clarify, when the car is idling at 10-12,000 rpm the rate is around 13-14V. When I rev the engine at 2-3000 rpm the voltage increases to the max of 16.1V Does that mean that when I am cruising, the voltage is maintaining the 16.1 V?
With this added information, do you still think I should adjust the regulator downward? Would I not then get much lower charging when engine is idling at the 10-12000 rpm.
Hope this makes sense. On another note, when I looked at the Moss Motors site; they sell a new regulator that is not pre-adjusted. The bulletin that comes with the part states how complicated the adjusting process is (just like the video you suggested) Is this because the new one has not been set up at all?
Thanks again,
Eddie
EWH Haynes

I meant to say, "unlike the simple video from Moss" explaining the adjustment
EWH Haynes

It sounds like someone has wound yours up to charge more for just pottering about and overdone it
They've gone for the 13-14 v at idle/low speeds instead of at max. charging speed----
16.1 v is way too high, on a longer trip it'll probably cook the battery and also kill globes etc
You need to back it off until you get an absolute max somewhere between 14-14.4 v at maximum charging/cruising speed (2-3000rpm)then at idle it will drop back to not much more than battery voltage--that's normal, the ign light might even come on dull or flicker at very low idle speed--normal
William Revit

Thanks, William for explaining this. I will take your advice and make the adjustment.
I really appreciate your help.
Eddie
EWH Haynes

Bringing a two bobbin regulator down to 14.5 V will not work:the open circuit voltage at 1500 revs and 68°F is 15.4 to16.4 Volts!!!
Dirk Van Ussel

Here's an extract from the Lucas manual.


Dave O'Neill 2

It appears that my regulator is set correct per the manual. It is the original regulator on the car that I have owned all these years; however, I am told that with changes in battery make-up in modern-days, the battery cannot withstand the higher voltages (16 or so). I will have to check mine to see if I can adjust downward and if not buy a new one that is adjustable. I also have the option of converting to the alternator but may hesitate since I am a "purist". (I must add, contrary to advice concerning damaging a battery; I have had no problems in recent years whilst driving the car occasionally at the higher rate.)
Eddie
EWH Haynes

In my TD the generator routinely puts out 15-16 volts at speed. I had the same battery for over 10 years and over 10k miles without any damage. I'm inclined to go with the manual excerpt above.

Jud
J K Chapin

"IF' you're running a dry battery I'd suggest getting an electronic controller that will be set at 14.4V max.---------if you're worried about originality you can hide it inside an original old case or mount it remotely somewhere else out of sight

All the specs being quoted by Dirk and Dave are parts of setting up a regulator with the battery disconnected and revs quoted are generator revs not engine revs-

If your regulator has been working fine for years without an issue,your battery is ok and the terminals nice and clean,, why stuff about with it----
William Revit

This thread was discussed between 12/10/2022 and 15/10/2022

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