Kelly KDH14800D controller:
This went into a state where it was basically "full on". So the motor went into an uncontrolled vvvrrrroooooommmmm!
Don't know why this happened, it was first thing in the morning so everything was cold. Possible that my precharge was not up to scratch, but seems unlikely.
Kostov 17R (9"):
After the controller failed I bought a new one. The new one was bigger (1000A vs 800A). This worked fine until I got a bit carried away and pushed the motor past its limits. I took the motor to a motor rewinds place who said that it would take a lot of work (1 or 2 thousand dollars worth) to rebuild. Since a new one the next size up costs $2400 delivered, I have now ordered one of those. Hopefully the new one will be less likely to die if I get enthusiastic in my driving.
The title "postmortem" on this post is probably a bit misleading. It sort of implies a level of knowledge which is above me. But I can at least take some photos of the bits:
This is the front bit (excuse my technical language). I think the motor guy said this was ok. Brushes are in good order and not worn down much in my 15,000km of use.
You can see some smoke on this middle bit ("rotor" I presume). The guy said that it measures as a short, and so would need to be pulled apart and probably rewound.
He pointed out the patina on this bit (commutator?) and said that was bad. Possibly due to too high a voltage.
I assume this is called the stator, and the coils are also burnt out. Maybe not all of them.
The motor guy was a bit dubious at the voltage I was using, he had written down that 124V was the rating of the motor. My controller can potentially give it 160V or so. I'm not sure where he got the 124V from, when I got home I could clearly see the label which says 144V. The Kostov website seems to indicate that voltage doesn't really matter too much except if there is no controller on the motor to stop it over revving (see my entry under "Kelly Controller" above!).
He could also not believe how little this motor cost.
And finally, here is a photo of the innards of the Kelly. There is no way that I am going to get it any more disassembled than this short of using a hacksaw. The case is one piece of aluminium - you can only take the ends off. It looks like two circuit boards have been slid down inside with the help of the six yellow spacers. Screws from the outside keep the spacers in place, and possibly some of them go through to the circuit boards. Every one of the 30-odd screws on the outside were covered in epoxy resin. I found that if I heated it it would go brittle and could be prised out of the phillips-head screws.
There are three large aluminium terminals running down between the circuit boards. There are heat-sunk components on the left and right, which have screws through from the outside to attach them to the aluminium casing.
This is the "waterproof" version of the controller. It has been filled with a rubbery stuff which I would say might be silicone rubber. It burns away with a hot knife soldering iron attachment. There are 8 plastic tubes running down the middle for some reason, these are not filled with silicone. To get any further I would have to destroy the case. I may do this someday if I get enthusiastic, but too much else to do right now!
