I've got two failed bag motors here. What gives?

I’ve sharpied over two commutation bars on the left stator, and one on the right.

These bars seem to be disconnected from the rest internally. I’ve measured resistance between all contacts except these, indicating an open circuit.

I’ve also checked if the copper stakes used to attach to the wire have disconnected, and they are not. The wires are very much still attached to the contacts.

What gives? Is the winding somehow broken internally? It’s not like a normal stall failiure where it burns up some enamel and causes a short. This is a disconnect unfortunately.

Both motors are from 2015 and seem to be from the same batch (same internals while other years have slight variations.)

Any thoughts what could cause this?

@Paul_Copioli knows more about the BAG motor than anyone else. There were some issues that he and his engineering staff identified with early production units; they also determined corrective actions that CCL subsequently implemented. Paul can tell that story in full, or as some parts of it might apply to the units you saw. My recollection is that some units were made with brush springs installed incorrectly.

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If those are 2015 units you should just throw them away. They are from the suspect batch that corrective action was taken to fix the issue.

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Thank you!

We did some more inventory checks and these seem to be the last 2015 bags we had left. Looks like they finally croaked.

Curious, what was the issue exactly?

You’d have to ask @Paul_Copioli for more details.

On our end, we’re unsure of anything we did specifically to cause this issue. The stator just seems to be disconnected somewhere inside.

The issue was a motor winding issue where they had too much tension in the winding rig and out permanent deformation on the wire. When it got hot it caused one (or some) of the wires to break thus causing no commutation.

Basically, the wire got pulled too hard and stretched like a piece of licorice.

Paul

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