Farmall Cub

I just put a new battery in my 53 Cub that hadn't been started in 6 months. The old battery wouldn't even take a charge. It popped right off with the new battery, but the amp guage didn't move. I checked battery voltage with a VOM, engine not running, at 6.3 volts. With engine running it's 6.5 volts. When I ground out the field terminal, it charges at 8.7 volts. The amp guage doesn't move under any of these conditions. I put a new (american made) VR on it less than 2 years ago. It sounds like the VR to me, or is the new battery only needing 6.5 volts to keep charged?


Tom

did you try and polarize it?, check for good grounds also
Tim

Tim, I did polarize it and ran a seperate ground. I'm stumped.


Tom

New regulators have to be adjusted, Make sure the reg. is for pos. ground , Remove the cover,You will see two contacts one for the cut-out side and one for the reg. side the gap on those points will need to be closed more or open more to set the charging.

twotone wrote:...... When I ground out the field terminal, it charges at 8.7 volts. The amp guage doesn't move under any of these conditions. .....

Sounds like the guage or wiring to me.

Your voltage readings at the battery indicate both that it is charging and that the regulator is working. I can think of 2 possibilities, one is that ammeter is bad, and second is that wiring is incorrect.

I haven't changed the wiring and the amp guage used to work, so I'm going try a new amp guage.


Tom

I thought that the amp gauge only showed positive for charging and negative for discharging. If it's charging at 6.5v, and the battery is at 6.3v the amp gauge should show 0, as it's likely not enough of a charge for the gauge to detect. The amp gauges on these tractors are really not that sensitive, and if it's the original one, it may be even less sensitive. It may have worked before because it was trying to charge the battery, but it was not taking a charge, therefore, showing positive charge all the time.
Just some thoughts.

Does the amp gauge show a discharge when the switch is turned on or the lights turned on? If not the gauge is likely not working.

Denny, the guage does not show a discharge when the lights are turned on. The needle does not move at all under any conditions.


Tom

In reference to the last two posts.

"A feature to be noted in connection with the combined current-voltage regulator is that generator output increases as the electrical load (lights, ignition, etc.) is added to the "L" terminal of the regulator. Since the load current bypasses the regulator current winding, it has no effect of the battery charging rate so long as the total load does not exceed the maximum output, controlled by the third brush of the generator, at operating speed. The third brush of the generator is not adjustable but is positioned to allow maximum generator output." Page 20-21 of the GSS-1012 Blue Ribbon Service Manual, Electrical Equipment. Turning the lights on should not make the ammeter move, if everything is working as it was designed to work (good battery, good generator, good regulator and good wiring).

The two manuals that are essential when working on the electrical system are the GSS-1012 and the GSS-1052-C. Covered in both of the manuals is a complete text for testing and maintaining the entire electrical system, including the maintenence, testing and setting of the voltage-regulator. If the battery is good, the generator is charging it sounds as if the voltage-regulator is doing what it is supposed to do.

After further testing, the volts do not increase with the engine running, in fact, they go down. I'm going to throw a VR at it and see what happens, easier than replacing a guage, and if it isn't the problem I have a spare VR, which is probably a good thing.


Tom

twotone wrote: I'm going to throw a VR at it and see what happens, easier than replacing a guage

Rather than sink money into another VR, I would recommend that you do as Oronc suggests, and check the gaps to ensure they are according to the manual specs. I went through several VRs. When the third one failed, I took the cover off and found that the gaps weren't quite right. Reset it, and she started charging again. I'm a packrat, so I had saved the previous VRs. Pulled the cover off one of them, and the gaps weren't right on that one either. So I reset that one, and it works now as well. Haven't tried the third one yet, but I suspect I will find the same thing.

More testing. With engine running, 6.3 volts going to and coming out of guage. Needle doesen't move. Engine running with field terminal grounded. 8.4 volts going into and coming out of guage, still no needle movement. Bad VR and guage?


Tom

The guage measures amps, not volts. Put an accurate Ammeter in series with the guage. The guage may be reading zero because it is shorted out.
With the engine not running, the ammeter should show a discharge when the lights are turned on. If this is not happening, then it has nothing to do with the VR.

Solve this issue before tackling the perceived charging issue.