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MG TD TF 1500 - Dead with the BIG DOG!

After a short drive to see some friends with the St. Bernard in the passenger seat my TD died. Luckily we were two houses away and the family came to my aid, along with an understanding neighbor.

It seems the battery is completely dead, this leads me to believe the generator is not recharging the battery. I have access to a neighbors trickle charger but I'm not sure if it's OK to attach to the TD (the positive ground is my concern), will I be OK?

How should I approach the possible generator problem? I'm willing to buy a device to measure the output of the generator but what device?

Finally, in anticipation of this happening some day again is there an issue with jump-starting a TD from a regular grounded US car? I presume positive-to-positive and negative-to-negative and it makes no difference that the vehicles have reverse grounds as long as their bodies don't touch or I don't act as a conduit with my hands. Help I'm fearful of a shock to the car or me.
Jim Tatol

Your right...no problem....pos/pos - neg/neg both for charging and for jump starting....
Was your amp gauge in the minus or your gen light on?

(thought you had hit a dog.....!!!!)
gordon lawson - TD 27667

You are in no danger of being shocked by 12 volts.
Connect up the charger red (positive) terminal to the positive post on the battery, and the black (negative) terminal to the negative post on the battery. This will work regardless of the polarity of ground. But see if the bigger(positive)post is connected to ground.
Someone may have changed it to negative ground.
Charge the battery with a charger, then start, and see if the ammeter shows the generator is charging the battery at 2000 to 2500 rpm.
Don Harmer

Actually Jim, The T-Series and many other early cars already have a good device to measure the performance of your system - Its called an ammeter.

An ammeter measures the LOAD of electricity you are drawing from your system. Today's cars don't have this. Instead they have idiot lights to tell when the VOLTAGE is too low (or too high).

An ammeter is actually a milli-voltmeter that gets its power from a SHUNT in the circuit. As more load is demanded, the shunt detects this and send it as a small voltage to the ammeter which then displays the load of your system in amperes (amps).

In summary, it is commonly possible to have a battery that can produce a voltage (say, from 12 volts to 15 or more volts in the case of the T-Series), but the battery for example, is too shot to produce the needed current (Amps) to run the electical system.

The voltage while directly related, will not give the true story of your charging system and/or your battery. That's why you need an ammeter.

As an example, next time you change some flashlight batteries because the flashlight is too dim, measure the voltage of the expired batteries. In all likelihood, you'll find they read 1.5 volts, the same as a fresh one; misleading one to think its still a good battery which of course, its not.



Gord Clark
Rockburn, Qué.
Gordon A. Clark

Thanks for all of the feedback.

I recollect that the ammeter needle was far to the right in the positive area, so I was thinking charging, so it was really discharging (correct me if I'm wrong). I spoke to my mechanic and he recalled that there was a small trickle charger in the storage above the firewall.

I've plugged it in as it is hardwired to the battery. I guess I should pull the battery and have it checked at Sears to see if it is holding a charge and if it is proceed to the generator. How do you troubleshoot generators? I'll be getting shop manuals soon so I won't need to post so many questions. I do appreciate your collective wisdom.

This BBS is the greatest thing since sliced bread.
Jim Tatol

Jim T. -- Nobody answered the important question of what instrument to obtain to check on the health of your electrical system. Let me just say that the new digital multimeters are the best thing since sliced bread to check out a cars electrical system. There are some advertized for less than ten bucks, don't. Pay more and get more! I like Wavetek meters as a quality meter at an afordable price. Look up Mouser or Digikey on the web and you will find Wavetek I am sure. The cheapies won't hold their calibration, the quality meters will hold their calibration for years. My friend , who is a professional restorer, trusted an old Radio Shack meter and burned up a generator for one of his customers because the meter was way out of calibration. He bought a Fluke model 78, which is an automtive meter, says it's one of the best investments he ever made (his marriage license was the other).One of the things that ISO 9000 requires is that you have your instruments checked by a calibration service every year.

Just make sure that the battery is connected the same way as the trickle charger. Trying to charge a battery with the wrong polarity is an excersize in frustration.

Try to get the battery back to full charge as quick as possible because lead/acid batteries don't like being left discharged, they sulphate, which requires a few charge discharge cycles to remedy.

Contact me off line if you need more info.
Cheers,
Bob
R. K. (Bob) Jeffers

Half the problems with cars in storage or not run regularly ends up being the battery...bet there are a lot of 'Lucas Curses' that ended up being just the battery. Odd that the charger is 'built in'... Sounds like your p/o didn't drive it much?
I stored a BMW 3 series each winter and went through 3 batteries in 5 years!
gordon lawson - TD 27667

Don't know about generators, but Advanced auto will check your alternator if you bring it in to them. May want to see if there is one in your area and see if they will do a generator.

Other alternative would be to go to a automotive electical rebuilding shop. They can check it and if it is bad, rebuild it for you.

Don't forget about your crank. Many a time I have had a low battery and the trusty crank got the TD going.
Bruce Cunha

Jim, if your ammeter was pegged to the right, i.e., max +, it might indicate that your generator is polarized opposite to that of your battery connection. If your battery is connected as positive ground and your generator is polarized for a positive output, it's output will only serve to totally discharge your battery. We just had some threads on this topic. Jumping and trickle charging will put some charge in the battery, but the generator will wipe it out.
Bud Krueger

Jim - You can test your generator as follows: to check the generator/dynamo - disconnect the wires from its terminals, connecting the two terminals together and to a multimeter set to the 20 or 25 volt range (here is an application where an analog meter is better than a digital one). Start the engine - DON'T rev it!! - just slowly increase the revs watching the voltmeter. It should get to 20v by the time you get to 1000 rpm. DON'T exceed 20v. If that checks out the generator is good and you need to satrt looking elsewhere for the problem. As Bob Jeffers suggests, check that the trickle charger is connected to the battery properly - positive to positive and negative to negative. Pulling the battery and having it checked is also a good thing to do. As a battery gets older, especially if it is not in a car that is used regularly, it will get to the point where it doesn't want to hold a charge (Bob Jeffers is the expert in this area). If the generator is bad, take it to a local auto electric shop as Bruce suggests, the generator in the T series cars is a very simple device and any good shop can rebuild them for a nominal cost, and they probably have all the parts on hand to do it. Finally, as Bruce said, don't forget the hand crank (and learn how to use it). Years ago, when the TD was being used as my wife's everyday car,the starter gave out. For the week tha tI had it out of the car to rebuild it, my wife continued to use the TD for all of her errands, just using the hand crank each time she started the car (she got a lot of stares whenever she did). Good luck - Dave
David DuBois

When I woke my XPAG-engined Y from a 4-year slumber it didn't charge, even after fitting the obvious new battery.

I don't know what work you can do yourself but I had a lot of fun dismantling the generator, cleaning all the contacts, taking special care of the copper(?) surfaces on the rear end of the generator and cutting down the bakelite(?) slots between them. After that work (and some cleaning of the regulator contacts) the charge was perfect.
If a car stands still for a long time (years) the generator has to be repolarised; search the archives for tons of info on generators and polarity.
Willem van der Veer

Back in early '60's I had a TD (one of many) that needed new brushes in the generator and the MG dealer was closed on Sat and I wanted to take it to the Gymkahana next day Sun so I went down to local auto parts and asked for set of gen brushes and jerk says "what kind of car" I says any kind he says no I gotta know what kind. I says OK Chrysler V8. He sold me a set I took 'em home and shaved 'em down to fit and they were still in the car when I sold it a year later. TD gen/sarters are the simplest things to work on and make right. Good luck on fixing yours.
Greg & Grimm
G.J. Cenzer

Hi,

I just disassembled my Lucas generator tonight. The commutator end is easy to get off, the pulley end, not bad. The cover on the pulley end will require a puller, not a huge one, but the bearing fits the shaft pretty tight. You might be able to replace the brushes with the generator still installed on the car, probably no fun, though.

What I found was not pretty. The brushes were worn to almost nothing, one down to the pigtail wire. Both pigtails were burned or broken off. The commutator has one segment that's higher than the others. And the solder has been thrown off the wires to the comm. segments. No wonder it felt really hot when I removed it.

I think it was reverse charging, the dash light got brighter as the revs raised. Kind of anyway. I never got stranded, the battery must be fine. Only drove a few miles with the light on. Darn Lucas stuff only lasts 85,000 miles. I am not the first owner, so I don't really know if it's the original or not. The year on the case is correct.

I have a spare genny in there now, but it's a bit noisy. Time to rebuild one, I guess. It's dirty work, all that greasy carbon. I think the arms are available, I have to check the fields yet. I think new complete units are under $100 US though. Would be nice to still have the year right.

You can definitely test the genny on the car. Here's a link (in the next post).
Tom

http://home.vicnet.net.au/~mmccv/Tech-Reg/Regulator.html
Tom

My Two Cents about Car Batteries.

Car Batteries are pretty simple devices, and I routinely get eight to ten years from the ones in my toy cars and boats by following these simple steps.

Recognizing that batteries have poor cranking performance, but wonderful storage performance the colder they are, I fully charge my batteries in October when I take them out of my vehicles. Yes, thats right, the vehicles go into warm storage at my warehouse, and the batteries come out and sit a foot above my concrete garage floor, in the back, on a steel shelf. The cold actually helps prevent discharge, and a fully charge battery won't freeze in any temperature we will see in North America (s.g. of 1.280, a fully charged battery will freeze at -90 Deg F).

In January, I give them a boost of charge, and agin in late April, anticipating that I'll be needing them soon.

Works for me!

warmly,
dave
Dave Braun

This thread was discussed between 17/07/2006 and 19/07/2006

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