Stator AC voltage output?

preynol1 · Feb 26, 2023

Does anyone know what the stators AC voltage should be at tick-over?
Cheers.

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Wull · Feb 26, 2023

It?ll be roughly 50-75v AC at 4-5k rpm give or take. You have to test each phase though, so 3 separate readings, and they should all be the same (ish).

What results are you getting?

preynol1 · Feb 26, 2023

Wull said:
It?ll be roughly 50-75v AC at 4-5k rpm give or take. You have to test each phase though, so 3 separate readings, and they should all be the same (ish).

What results are you getting?

Cheers . No where near those readings. One phase 6v and the other 2 are about 20v at 4K. Tick over 11v for the 2 and below 5v for the lower. Looks like one coils burnt out. It would explain charging issues

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Wull · Feb 26, 2023

I?m guessing you have the multimeter set to the correct settings? AC min range 100v?

Yeah 100% at fault, what is the actual charge rate at the battery? I?d expect it to be low with that output from the windings, you?d probably find the regulator rectifier would be working its arse off trying to compensate for that low output.

When you remove the stator cover and stator you?ll probably clearly see the burnt out windings.

preynol1 · Feb 26, 2023

Wull said:
I?m guessing you have the multimeter set to the correct settings? AC min range 100v?

Yeah 100% at fault, what is the actual charge rate at the battery? I?d expect it to be low with that output from the windings, you?d probably find the regulator rectifier would be working its arse off trying to compensate for that low output.

When you remove the stator cover and stator you?ll probably clearly see the burnt out windings.

Exactly the fault that started the investigation. Flat battery and poor running.
Can?t find why it failed yet but suspect it?s a gradual degradation.
Found some pattern parts but going to ask BMW cost for a OEM for a laugh.

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