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MG MGA - Dead Battery?

I have a 1957 MGA that recently underwent a total engine rebuild and has been running great.
I was driving it this week and when I got home the battery was dead and the car would not turn over. I had used the headlights for only 5 minutes before returning home.
I put it on the trickel charger over night and it starts just fine now. I did notice that after being on the charger for 14 hours it still showed the re light indicating still charging, rather than green for fully charged.
Do I just need a new battery? Could there be a problem with the battery being recharged while running?
Since there is no ampmeter on this like my TD I cannot tell if battery is recharging. Any suggestions on how to test this?
The battery was in the car when I bought it 3 years ago.
Many thanks,
Bill Chandler
W Chandler

Bill, On the rebuild and getting it back on the road and after installing the battery, did you "flash" or polarize the generator. It is an easy thing to do and there is lots of info on the "net" on how to do this. If the generator is not polarized, it may not charge, so try this first.

Keep your "smart" charger on the battery for a day or so to bring the charge up before further testing. The green light should come on eventually.
C.R. Tyrell

Thank you for your comments.
I have driven it about 600 miles since the rebuild, so I would have to assume that the generator is polarized OK. Does that make sense?
Bill
W Chandler

Bill. No, that does not make sense. It is possible to drive a car several hundred miles operating on the battery (batteries) alone.

First question. Do you have one 12 volt battery or two six volt batteries? If one six volt battery is going out, it can drain the other battery.

Second. Do you have the original generator or have you replaced it with an alternator?

Third. Do you have the factory workshop manual for your car? If not, you need to get it. It contains the set up procedure for polarizing (when necessary) the generator and a series of tests to determine if the control box (mechanical voltage regulator) is working correctly.

Fourth. Is you car still positive ground or has it been converted to negative ground? If converted to negative ground, was the generator properly polarized after the conversion?

When charging a suspect battery (batteries), make sure you remove the ground cable clamp from the battery and the cable going to the starter solenoid. This isolates the battery and allows you to see what happens. If the clamps are not disconnected, you add in the rest of the electrical system as part of your diagnosis problem. Best to start with a single variable, then add a single variable, and continue, one point at a time, until you have the full system checked out.

Les
Les Bengtson

Bill,

While the need to re-polarize your generator may be necessary the question as to whether your battery is toast or not is simple. Yes, it is. If it hasn't taken a full charge after 14 hours on a charger then it's got at least one, if not more, cells dead.

Gene
Gene Gillam

The one thing that I added to my dash that has been a great help, is a volt meter....I got one that fit in with the other gauges....It tells me if the system is charging, and at what voltages....It also makes adjusting the regulator, a snap. Much better than an ammeter, IMHO, as ammeters have all the battery current running through them, and can (and have) caused electrical
fires.
Edward



E B Wesson

This is 12 volts.
Original generator - not alternator.
It is positive ground.
I do not have workshop manual.


I took the battery to AutoZone and they checked it and said it was fine at 79% charged.

I bought a voltage measuring device, since I was told that the battery should be between 12 and 13 volts with engine off and around 14 if it is recharging.

I tried this on my 09 BMW and sure enough 12.2 engine running and 14 when running.

On the MGA it was 12.4 engine off and 12.2 while running ó 12.0 running with lights on.

Is this in fact evidence of no battery charging?

Do you know how to test the generator directly to see if it is working OK. There is one loose fitting on the back of the generator where one of the wires attaches. This could be an issue.

I understand that the voltage regulator can also be an issue, but donít really know anything about it.

Thanks-
Bill
W Chandler

Bill, the IGN light should go on when you turn the key, then off as the battery charges. Does the light go off?
Since your voltage is lower when running, I'd say you are not charging.
Check the dynamo output with the F and D terminals bridged but otherwise disconnected. You should get >20V at about 1500 rpm. Don't go over 2000.
This will also tell you if you are polarized correctly.
If you do get a decent output, its your regulator at fault.
Art Pearse

Bill,

I was across the street from you on Saturday at my grandson's birthday celebration. I should have walked over and introduced myself.

I can easily determine whether your generator is charging or not and would be glad to do so.

If you'd like, I'll be available tomorrow and Tuesday (6/16-17)after which I'll be way out of touch up on Beaver Island for a week.

We're all in this together!

John
JR Alexander

Bill,

I was across the street from you on Saturday at my grandson's birthday celebration. I should have walked over and introduced myself.

I can easily determine whether your generator is charging or not and would be glad to do so. Should only take 10 minutes.

If you'd like, I'll be available tomorrow and Tuesday (6/16-17)after which I'll be way out of touch up on Beaver Island for a week.

E-mail me.We're all in this together!

John
JR Alexander

It does seem that there is no dynamo output and if there are no obvious bad connections I would suspect the dynamo brushes................Mike
m.j. moore

Bill;
Download yourself a copy of the Lucas Electrical Correspondence Course. It is available on the net, and I am sorry I can't find the link for it right now. It covers where to check, how to check and what needs adjusting and how to. Also covers everything else electrical in the car. A valuable resource. Maybe someone has the link. Generators are easily re-built if necessary and not expensive to to this.
C.R. Tyrell

Lucas Technical Service,
"Overseas Technical Correspondence Course"
http://mgaguru.com/mgtech/books/lts_otcc.htm
Barney Gaylord

Thanks Barney
C.R. Tyrell

Thanks for all of your collective help.
I have determined that the generator is bad - not working.
How do I find someone in the Detroit area to repair an old British generator?
Bill
W Chandler

Any auto electric repair shop should be able to do it. They are very similar to Delco-Remy generators. Also Tractor dealerships and agriculture service shops, as many old tractors use Lucas generators.

C.R. Tyrell

C.R. --Thanks - very helpful.
Bill
W Chandler

Michigan? Michigan? Why do I remember the name of that state? Mayhap because one of the finest MG mechanics in the world (if not the current finest) lives there and has a shop there? Hmmm
Les Bengtson

I just dropped the generator off at what appears to be a perfect place in the Detroit area.

It is called Auto Electric International, 22211 Telegraph Rd, Southfield, MI.

He bench tested it this morning when I took it in and verified it is dead. Said it would be ready in a day or two.
I will keep you posted on the results.
Bill
W Chandler

Most generator/alternator shops , fix these very reasonably....
Around here, typical cost is around $70....
I will be interested in knowing what your cost will be.
Edward
E B Wesson

Just picked it up and reinstalled it - it works great and cost $100, which I think is reasonable.

I would highly recommend the place listed above - Auto Electric International, Southfield, MI.

Bill
W Chandler

This thread was discussed between 14/06/2014 and 21/06/2014

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