fbekholden.com

Hi all
Is there anyway to bench test a generator to see if it is any good. I tried it on a bench with a multimeter, but dont really know what I’m looking for.
Thanks
Jason

Jason,

Visual Inspection First. Pop the commutator cover band off first, and inspect the inside for thrown solder. If there is thrown solder, the generator's basically bin-worthy. Pull up the brush springs. If they're weak or broken, they'll need replacing. With the brush spring held up, pull gently on the brush lead to make sure the brushes run freely in their holders. Check that the brushes are not worn out. Rotate the pulley and check that the generator's not seized. Rock the pulley from side to side and look at the commutator. If the commutator moves more than a few thou, the bush is worn, and the generator armature risks rubbing on the pole pieces. Inspect the commutator for pitting and signs of arcing. If one segment only is pitted, that means a shorted armature. Generator good for the bin. If all the segments are pitted, it means the generator needs new brushes. If the commutator is smooth, but black in colour, polish lightly with wet'n'dry.

No thrown solder? Spins freely? Rear bush OK? Brush springs OK? Brushes free in their holders? Commutator clean? Then grab a car battery, and do the following tests (Note: connections are different for Bosch and Lucas).

1. Bosch: Connect the D+ terminal to battery positive. Connect a wire with a test clip (or bare end) to battery negative.
Lucas: Connect a jumper lead between the generator body and battery negative. Connect a wire with test clip (or bare end) to battery positive.
Both: Then lightly brush the test clip or bare end against the DF terminal.
If there's a spark as you disconnect, the field coil is OK.

2. Both: Connect a jumper lead from battery negative to the frame of the generator.
Bosch: Connect the DF terminal to the frame of the generator (battery -).
Lucas: Connect the DF terminal to the D+ terminal.
Both: Connect a jumper lead from battery positive to the D+ terminal.
The generator should spin, slowly, in the same direction as it is driven on the engine.

If the generator spins in test 2, it is OK. The only other thing to check is the condition of the field coil wrapping, but it's best to pull the generator apart for that.

Rob

Thanks but already worked it out. Generator is all good

I'm storing this post in the "things I really should know how to do, but have never asked" file. Great guidance. Deserves a sticky in the Electrical section methinks.

Cheers,
Harv

The one i sent you Jason?

FB ute driver, EK van project

Yeah just tested it before I painted it.

Glad it works

FB ute driver, EK van project

Harv wrote: ↑Fri Sep 17, 2021 4:20 pm I'm storing this post in the "things I really should know how to do, but have never asked" file. Great guidance. Deserves a sticky in the Electrical section methinks.

Cheers,
Harv

I was thinking the same Harv - definitely a sticky, great info thanks Rob.