Electrical Question

[Johnbo]

I have a 1947 Cub and was using the battery to start it with no issues. Last year I went to start it and the Ameter busted, glass broke and there was alot of sparks. At the time I was not using the Cub too much and it started well with a hand crank so I did not attempt to fix it. I put a battery in today in an attempted to start it and nothing happen. I checked and cleaned the ground and conections. Not sure how to go forward on identifying the issue. Any suggestions would be appreciated.

Thank you ,
John

[tst]

1st thing is to make sure you have good battery connections at both ends of the cables, also the amp meter is part of the charging system and will not charge with that broken

[Crimson Tim]

The more important question to me is why did the meter blow up in the first place? I don’t have any suggestions on that, unless something presents itself on examination.

Is this still on mag and generator? Or alternator conversion?
If you’re not getting continuity through the meter, it won’t run or charge, but I would expect it to at least turn over. Unless someone swapped the mechanical switch for a relay.

[WildFarmall]

I have a 49 Cub with a charging problem. I had the generator serviced and still no charging. I bought a new amp meter but have not installed it yet. does the amp meter control charging of the battery?

[tst]

attached are flow charts to find the problem, if you still have the stock system made in 49 it should be the chart using the cutout relay

[ctltmp]

Hi. I have not heard of an ammeter bursting like that. There are a lot of wise cub guys on the forum that can help you.

Wildfarmall, I have a 49 that drove me wiring crazy. Is was a mixture of original and updated which is why it never made sense. A lot of earlier Cubs just came with crank start (that was my case). Later they offered an upgrade. Depending on when you purchased the upgrade made a difference in what you might have. Although I completely rewired my 49 when I refurbished it 2 years ago, I decided to purchase a harness and redo it again.


If you give brillmam a call (bottom of page) they are a wealth of knowledge as well.

Good luck to you both.

[Eugene]

Does the amp meter control charging of the battery?

No. It's simply a meter that indicates the amount of amps, the charge or discharge, flowing through it.

[Gary S.]

Does the amp meter control charging of the battery?

No. It's simply a meter that indicates the amount of amps, the charge or discharge, flowing through it.

But all power flows thru an amp meter before it goes anywhere else with maybe the exception of the starter. If it were to go open power would not go through it to the ignition system or to the charging circuit right? Thats why voltage meters are now used they are safer, probably the real reason to use them is that they are cheaper as well.

[halftonstude]

Except starter current, the starter is wired direct to the battery. all current except cranking current goes through the ammeter. Otherwise the meter would go poof. Ammeters come in one of three vareities: first is the newest and involves hall effect transistors and transducers, no need to discuss here. Second is a meter with an external shunt. A shunt is a big fancy calibrated resistor. the relationship between voltage across a resistor and current going through a resistor is perfectly linear, so if you have a meter (50 millivolts for example) and a calibrated resistor that says "1000A 50mV" then if you hook up the meter you can accurately measure current. WHen there is 50 millivolts across the shunt, the meter will go full scale and you'll know you have exactly 1000 amps going through the shunt. Last kind is what we have in the tractors, or many automobiles have in their dash boards. Last kind is kind of like the second, except the resistors is inside the ammeter. The ammeter acts like a hunk of wire - its job is to measure, not modify the current that's going through it. My guess as why an old ammeter would go poof would be the insulating bushings or insulating paper that keeps the electrical contacts from touching the frame of the ammeter have failed or a component inside became loose. Because the ammeter is connected to - battery and everything around it is at ground potential, anything happening inside that that involves -battery coming in contact with anything around it would be bad. It lets the smoke out. And we all know smoke is the basis for electricity, because when it's gone, nothing works... like your ammeter!
HTH
c

[WildFarmall]

I am still not understanding what wiring diagram I should be using. I have a 49 Farmall Cub. How do I tell if I have a generator or alternator? It is a 12 volt system.

Is the attached file the one I should be using?

[Glen]

Hi,
A 1949 Cub was originally 6 volts, positive ground.
Below is a page from the 1949 Cub operator's manual showing the original electrical system.

The cutout, or Relay, IH called it is on top of the generator.

http://farmallcub.com/rudi_cub/www.clea ... age-33.jpg

The gens originally had a plate with the Delco model number, it was usually 1101355.

An alternator is not as long as a gen, and usually aluminum colored, unless it has been painted.
Below is a pic of a Delco alternator someone put on a Cub.

[Eugene]

I am still not understanding what wiring diagram I should be using. I have a 49 Farmall Cub. Is the attached file the one I should be using?

Maybe and maybe not. Gonna depend on your answers to the following.

How do I tell if I have a generator or alternator?

Internet search will have pictures of common alternators and generators used on tractors or automobiles.

It is a 12 volt system.

Are you sure? Most automotive alternators are 12 volts. Generators, either 6 or 12 volts. Common alternators are of the 3 wire or single wire style.

The tractor wiring varies by generator voltage, alternator style and a couple other things.

[WildFarmall]

Looking at your picture, I have an alternator with a 12 volt system. What wiring diagram should I use?

[staninlowerAL]

Looking at your picture, I have an alternator with a 12 volt system. What wiring diagram should I use?

You have a hybrid system if it's an alternator. Could be internal or external regulated. If you have a true conversion most likely you have a conversion to 12v using either a std 6v distributor or a mag that is converted to use a 12v external coil but that's not always the case. Your system could be still using the mag for the ignition system and the alternator to run the other electrical components i.e. battery charging, lights, etc. Pictures might help sort out what you have. Stan

[Eugene]

Forget using any wiring diagram until we sort out your ignition system and which type alternator you have.

Post several pictures of each of the following:
Back side of the alternator showing the wiring connections.
Ignition system showing what you have - magneto or distributor and or ballast resistor.