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MG TD TF 1500 - Voltage Regulator Settings

Now that I'm back on the road,one of the minor things that need to check on is the voltage regulator setting for my 1953TD. It is a 5 post type, but looks slightly different than the one in the workshop manual. It says Lucas, and has an adjustment on the top of the left coil (as you face it with the terminals to the front), and two adjustments on the back metal plate, one for each coil.

My concern is whether I am overcharging. When I set the regulator up two years ago, I set it for 16.5 volts, per the manual. I got a lot of suphation on the battery, so I figured I must have been boiling the battery by setting the regulator too high. The ammeter would be at zero at idle, but pegged to the right (30amps) when underway.

Today I followed the workshop manual directions, and readjusted the regulator. The readings are as follows: At idle, 11-12 volts, and the ammeter is at 0 to slightly negative. At moderate speed, about +5 amps. Accelerating hard or at speed, it can go up to 15 amps, occasionally hitting 20. This is with the headlights off.

Does this sound right?

Ira
Ira Spector

Seems like those readings are about the same as the ones I see on my car. The amount of charge will diminish as the length of my trip increases. I interpret this as showing that the battery is regaining its full charge. I have never taken any voltage readings at the regulator nor have I had any need to change the factory settings. I subscribe to the saying, "if it aint broke, dont fix it. Mine shows a slight charge at cruising speed with all the accessories like the headlamps, heater fan and radio turned on.
Jim Merz

Thanks Jim. I do agree with your philosophy. When I did the mechanical restoration two years ago, the car wasn't charging. After cleaning the contacts and then adjusting the voltage regulator, it would not stop charging. I had followed the manual, which has some pretty high voltage settings in it (like 15-16.5 volts, depending on temperature). I was getting a lot of corrosion (sulphate) on the battery, so i decided to readjust the voltage regulator before it started to ruin my new paint. So what I'm getting now sounds more like it should. I did forget that as the car runs, the battery should charge up and the number of amps should decrease; your note reminded me of that.
Time will tell, but it sounds like I'm on the right track.

Best,

Ira
Ira Spector

My orig. 9/51 regulator in the attic is exactly like the picture, all of the replacement ones look different like you described. I think you are fine now- seems like mine is about the same.
George Butz

Several years ago I bought a Lucas service manual from MM which has lots of detail on how to adjust the regulator......highly reccomended.
colin stafford

Thanks to all. I drove the car last night with the lights on, and am now reasonably confident that all is fine. When starting out, the charge rate is about 10-15 amps, and higher when accelerating. When the lights are on the charge rate drops after about 10 minutes to around 5 amps at speed. At idle, with the lights on, it drops to between 0 and -5 amps. But when moving again, it goes back up to about +5 amps. So things seem to be fine; it looks like the battery won't be overcharged, nor will it discharge when at speed at night.

On to my next minor problems; the speedo cable and turn signal control box!

Best,

Ira

Ira Spector

Has no one made a solid state conversion for the cut out / rgulator. Surprised there is nothing similar to the kits for the SU pump. Power transistors and diodes are so small these days surely something could be designed that would fit under the standard bakelite cover?


Jan T
Jan Targosz

This thread was discussed between 08/09/2003 and 12/09/2003

MG TD TF 1500 index

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