Westcoast Posted May 6, 2021 Report Share Posted May 6, 2021 Seems my lad was able to dislodge a motor magnet today. The motor is a 36V 900W version. Anyone seen anything like this before? Unfortunately he didn't mention the power change he felt until later and there wasn't any noise so we kept riding for about 10 minutes more. As the pic shows the motor became extremely hot. And amazingly, it still runs. I haven't disassembled the brush side yet. I am curious what the consensus is here. Can it be rebuilt (should it be?) or just replace it. At this moment it seems like a replace to me (I know nothing about electric motors) but I was curious if anyone has been here before. Looks pretty nasty to me. Thanks all for the advice. Quote Link to comment Share on other sites More sharing options...
arthritic Posted May 6, 2021 Report Share Posted May 6, 2021 I've repaired 4 now with https://www.permabond.co.uk/product-page/permabond-ta437-1-x-50ml-resin-1-x-20ml-initiator-41#! None of the repaired ones have failed, its always been the originals. Keep your fingers out of the way when you put the windings back in the outer case. Quote Link to comment Share on other sites More sharing options...
Westcoast Posted May 6, 2021 Author Report Share Posted May 6, 2021 Thank you for the info arthritic. I had a chance to pull the brush end-cap off this evening and theres 2 broken copper winding lines broken to the Commutator. Theres also some sign of light surface corrosion on the bearing at the brush-end too. The drive-side had none. Perhaps moisture is a contributing factor for the failure, or at least initiated it in some way. Would it be worth having the armature re-wound? Regarding magnets, of the 4 total two are well-adhered to the frame body and two dislodged. Interestingly, and very odd to me, the two which dislodged have almost NO magnetic properties. They wont self-adhere to the frame body at all nor attach to anything ferrous (a screwdriver, for example). Is this normal for these motors? I would have thought each of the 4 magnetic panels would be actual true magnets. Thanks again. Quote Link to comment Share on other sites More sharing options...
arthritic Posted May 6, 2021 Report Share Posted May 6, 2021 I would buy new rather than cost of rewind. First magnet failure we had cost me £160 at local motor place and they estimated over £300 if a rewind needed and no guarantee, luckily it wasn't.. That's why I did everything myself afterwards. Water is a problem, even if you fit a seal on the motor shaft it soon leaks so I ignored it and just dried things out whenever the motor was opened to fit new drive side bearing. My motors where on a Mecatecno T14 but very similar. Quote Link to comment Share on other sites More sharing options...
Westcoast Posted May 7, 2021 Author Report Share Posted May 7, 2021 Thanks again for your insight. A new motor is the best option. It was a mystery why two Neodymium magnets lost all their magnetic ability so I did a little more research on effects of temperature on our motors. It seems we want to stay far away from the Curie Temperature value of 320C where permanent damage occurs. Ideally we should stay under 80C for best performance. In my case I believe it may have exceeded 300C, and on further inspection of armature wiring, it looks like I can see a small blob of melted copper! Thats insane heat. Does anyone know what normal operational temperature is? Also I might try to seal the new motor with some polyurethane to further weatherproof it but now I'm also considering a heat sink. Quote Link to comment Share on other sites More sharing options...
Westcoast Posted May 23, 2021 Author Report Share Posted May 23, 2021 Follow-up for closure of this thread. Ordered a new motor from OSET USA (thanks guys!) and installed it. Performance is so much better. Sound wise, its noticeably a lot quieter. Without touching knobs there's more torque to the rear wheel and battery life seems better. My assumption at this point is the motor became contaminated so it started generating excessive heat and basically self-destructed. The shaft-seal looked fine when I disassembled but maybe dirt got in from between end caps and the body. I've sealed the new one a bit more. I'm monitoring temperature on the new one and during constant use after an hour its getting up to 50 degrees C. Problem solved. Quote Link to comment Share on other sites More sharing options...
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