Weird electrical puzzler - breaker pops, the PT1850 runs better until it's shut off

[MikeOConnor]

That's right where my thoughts are headed -- one side of the fan and thermostat are still connected. More reports at noon.

 

[MikeOConnor]

That's right where my thoughts are headed -- one side of the fan and thermostat are still connected. More reports at noon.

 

[Soundguy]

the easy way to troubleshoot problems like this is to incrementally unload the distribution system. IE.. isolate a load, one at a time. when you finally isolate a load , and no more line faults occur, then you run that circuit and see what it's problem is.

 

[MikeOConnor]

Here's the report from this morning:

- the fan and thermostat are disconnected

- the operator seat is disconnected

No change yet. This afternoon I'm going to pull the Yellow (accessory) wire off the ignition switch and see what happens.

 

[MossRoad]

middle left

You mean that thing that says "Alt".....


hahahahaha thanks. Geez!!! :confused3:

:laughing:

 

[MikeOConnor]

Pulled the yellow wire off the ignition switch:

- Dash instruments go dead... Oh, they're fed by that circuit. OK -- meter on the battery
- Tractor starts
- Tractor runs indefinitely without popping the breaker
- Battery voltage declines just a bit (rather than going up to charging voltage)

Seems like the alternator is indeed backfeeding through the accessory side -- wish I'd remembered to do this yesterday, but there you go. When the accessory circuit is removed, the alternator does NOT charge the battery. I can't quite figure out what the *correct* path for the alternator to go to the battery is. If the only path is yellow back to the ignition switch then I'd think the open breaker would block it.

 

[LD1]

Pulled the yellow wire off the ignition switch:

- Dash instruments go dead... Oh, they're fed by that circuit. OK -- meter on the battery
- Tractor starts
- Tractor runs indefinitely without popping the breaker
- Battery voltage declines just a bit (rather than going up to charging voltage)

Seems like the alternator is indeed backfeeding through the accessory side -- wish I'd remembered to do this yesterday, but there you go. When the accessory circuit is removed, the alternator does NOT charge the battery. I can't quite figure out what the *correct* path for the alternator to go to the battery is. If the only path is yellow back to the ignition switch then I'd think the open breaker would block it.

The open breaker does block it. With the breaker popped and everything else hooked up, you are NOT charging your battery.

you have confirmed the the issue is indeed in the yellow circuit.

Now start breaking down the yellow circuit. Either unhook all of them and re-attach one at a time til the breaker pops, or unhook them one at until the breaker quits popping. Or get a DC amp clamp and go to town.

Just too many things on that circuit to begin to speculate. Gotta start isolating. You have already ruled out the fan switch, t-stat, and seat. Keep going.

I'd actually start with unhooking D+ on the alternator. Perhaps there is an issue with the field pulling too much current, or even the internal regulator messed up or a dead cell in the battery and allowing it to try to force too much current back through the breaker causing a trip

 

[MikeOConnor]

The open breaker does block it. With the breaker popped and everything else hooked up, you are NOT charging your battery.

But but but... With everything hooked up the battery voltage jumps up from around 11.8 with the breaker set, to 13.2 when the breaker is blown. Doesn't that imply that the battery is being charged? Or is there some other way to get the voltage that high? UPDATE The battery at rest is sitting around 12.4 volts. /UPDATE

 

[Soundguy]

I'm exactly in agreement with ld1. Break down that yellow circuit, and yeah, I'd start with D+

Where is the volt meter ? My guess is it feeds somewhere off yellow, and not the breaker to battery side. Thus you are reading alt voltage.

 

[MikeOConnor]

I love it when smart folks are in agreement. OK, tomorrow I'll work through that Acc circuit starting with D+. I was using the volt meter on the dash until I killed it by pulling Yellow off the ignition switch then I switched to VOM across the battery. I may try putting yellow back on and measuring voltage across the battery with the VOM through the transition from breaker-closed to breaker-open too. Thanks!