Farmall Super A not charging

[J Star]

I have a 1954 Super A that has sat for a couple of years due to my working out of town. Took a week off and went to start it up. It had been converted to a 12 volt system before I purchased the tractor. I have had no charging issues in the past until this point. I replaced the alternator after having it tested and started it up. While it is running, after jumping off due to weak battery, I disconnect the cables; at which time it should run off the alternator, but it dies. When I test the voltage to the battery while running, I am getting crazy voltage readings from 40 to the 100's. I understand some when it comes to electrical issues, but this has me stumped. If someone can help, it will be greatly appreciated. Thanks

 

[Clint S]

What kind of alt is it and do you have the exciter circuit wired in? Due to the simple nature of the tractor there is little load and many alts and they can charge a little high at around 15+- volts. Second I would verify your meter, 40 to 100 volts is crazy. Last you can damage the alt by disconnecting the battery it takes the charging load off and voltage can spike.

 

[J Star]

It is a Delco single pole w/2 prong regulator/ field connection, the same as the one I removed. The meter reading was jumping as I attempted to read the voltage across the bat to see if there was positive voltage. As for the exciter circuit, all I did was install the new alternator to the existing harness, so I can't answer this part of the question without knowing where and what the exciter circuit is.

 

[Clint S]

Take a look at this and look at your wiring and see if everything adds up.
Yesterday's Tractors - Step by Step 12-Volt Conversion

They are all pretty much the same so the above link being an M is pretty close to the A wiring

 

[J Star]

After Googling this, it looks like the wire that feeds from the fields back to the post is the built-in exciter circuit. But I could be wron.

 

[J Star]

Thanks. I found this today and went over the existing wiring and all looked to be intact. I also checked the continuity of existing wiring and all traced out well. I will once more the system tomorrow though to make sure I didn't miss something. Thanks Clint S.

 

[skyhook]

While it is running, after jumping off due to weak battery, I disconnect the cables;

This part has me confused.
Why would you disconnect the cables....if the old alt was defective and your sure the new alt is good,( you didn't say whether or not it was new) the old alt may have damaged the old battery.
Make sure your meter is working properly and your battery is also still good.
What type of alt is on your machine , can you provide a model # or a pic of it.

 

[Dave M7040]

The odd voltage readings may mean that AC current is getting out of the alternator because you damaged the rectifier inside.
Dont run without the battery as the alternator needs a reference to decide how much to charge.
Likely time for a new alternator. Not too expensive if you are using the GM ones.
Dave M7040

 

[J Star]

I am removing the jumper cables used to start the tractor battery connected to another vehicle. When I remove the jumper cables (the bat on tractor is too weak to start it) the tractor dies.
Here is a photo of my tractor. It is a 1954 Model that originally came with the 1 point hitch, converted to 3 point.

 

[J Star]

The alternator is a new one and I took it back and had it tested. All was ok with alt. I am leaving the tractor battery in and connected, when the jumper cables are removed it dies.