MF35 charging system question

[mf35]

Just finished restoring a MF35 perkins diesel and have some confusion about the charging system. I've had the generator checked twice and it is good. The voltage regulator is new as is the battery and complete wiring harness. Everything is working but I'm not sure if the generator is putting out correctly. The ammeter shows discharge when the lights are on and the engine not running. It also shows discharge when starting the engine but goes to the middle when the tractor is running. I've read different ways to excite the generator or regulator but none of them seem to help. I'm needing some advice on where to go next in troubleshooting this.

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[JJ. in B.C.]

Your restoration looks very nice. I am not sure what you are trying to troubleshoot, it sounds normal to me with a new battery

 

[Joe Ferguson]

If the battery is full charged and engine is starting immediately the ampmeter will show charge for few seconds and return to 0.

You may put lights on for 5 minutes with engine not running to put slight discharge on the battery and then start the engine if ampmeter shows o again there is a defect it is supposed to indicate charge for few minutes. Generator systems need certain revolution of the engine to start charging.

The generator will not charge at engine idle it needs sometimes 1000 ~ 1200 RPM to start charging. An alternator will charge at idle it is defferent than a generator.

With a generator at idle speed if you put all lights on.. the ampmeter will show discharge if you increase RPM slowly you will see it beginning to charge at 900 ~ 1200 RPM depending of the VR adjustment the age and state of the battery and charging system.

My 2¢

Joe Ferguson

 

[Joe Ferguson]

Forgot to mention that I would like that at least one of my tractors look's like yours. Vey good job !

Joe Ferguson

 

[mf35]

Joe, thanks for your comment. The tractor caught fire in 86. I acquired it a few years ago and just got around to restoring it. My confusion comes from not being real sure that the generator is putting out current. I've read and have been told how to excite the gen or VR. One article says to disconnect the F terminal on the gen and jumper it quickly (1 sec) to the battery hot side. The shop who checked the gen said to leave everything connected and jumper from the gen terminal across the bat terminal on the VR with the tractor running. I guess I need clarification as to which procedure is correct and how to test to make sure the gen is charging properly. I did take a voltage reading across the battery cable to the battery terminal (+ side) and got a reading of 12.4V at idle but it didn't increase as the rpm went up. With the cable connected and the tractor running the ammeter went to the discharge side when the lights were turned on and stayed there as the rpm increased.