Hub motor suddenly stiff to turn, now OK...Solved

[NeilP]

I am pretty sure the only way to resolve this is going to be strip it down and look inside , but I am now away in Canada for 2 weeks so not able to work on it till it get home

I went to leave work last Friday, and the motor was stiff to turn, almost as if the phase wires were shorted together
So i disconnected motor from controller, and the issue was the same, initially stiff with to turn and then fractionally easier once turning

Plugged back in and gently applied power.... Motor turns as nomal, no unusual current reading from CA
Carefully started to ride home.... 8 miles. All fine, no unusual heating or current issues, still pulling 45 or so mph, but did not get a chance to try continous burst for a long enough period to get up to full speed There was just too much traffic

Get home and motor now spins fine, freely by hand exactly like it has done for past 2500 miles

 

[dogman dan]

Sounds like shorted phase wires to me. Odd that they would short enough to make the motor cog, but still run ok. Intermittent sounds more like a nicked wire to me, than shorts in the controller.

 

[Ykick]

Sounds like shorted phase wires to me. Odd that they would short enough to make the motor cog, but still run ok. Intermittent sounds more like a nicked wire to me, than shorts in the controller.

I'd be concerned enough by this to carefully check all external phase motor wiring and connectors. Particularly, wires through the axle opening. Dunno if I'd go inside the motor yet? I'd probably wait for it to happen again before I'd go there.

 

[NeilP]

Yes, I was assuming phase wire short too, but wanted to check

Getting the wheel off the bike is a far bigger job than removing the side covers to check inside, ...once it is off, so when nI do get it off the bike, sideccover will be coming off too

Cheers

 

[John in CR]

Maybe the brake handle was pushed. An X5 turns smoothly with a short unlike the newer types that are clearly notched in the turning resistance and easier to identify. A phase short isn't going to go away like that, and a phase short will get noticeably harder to turn the faster you try to turn it, not easier. Messing with motor wires and popping covers off unnecessarily is asking for trouble AFAIC.

I'd suggest first disconnecting from the controller, and short a couple of phases together to see if it feels the same. Inspect the wiring outside the motor for damage, and feel your phase wires for heat immediately after your most demanding type of riding. Wires don't just break by themselves, so unless they're damaged or melted it doesn't seem likely. A phase wire short certainly isn't going to fix itself, and then run properly, and not get immediately worse, so it seems unlikely, not impossible, but unlikely.

Have you had the motor opened before? Did you buy it new or used? Do you ride in the rain, and if so, do you have a proper drip loop? I've seen working motors that I bought used with so much corrosion from water getting in that they were nearly locked up upon arrival down here, and I've heard of working motors with lots of water in them. Without a drip loop, water follows the wires right into the motor. I can easily see that causing your symptoms.

 

[NeilP]

Hi John,
Thanks for the ideas,
First thing I tried was disconnect the phase wires, and it felt the same, but can't remember if I tried shorting ghem manually

Big drip loop, and it was a dry day
Motor was new, and I have had it apart a couple of times, once when I first fitted longer mil
Spec 10 g wires,and again when Crystalyte sent me more of the correct style PTFE covered wire

I admit, I did think it strange that what appeared to be a short, should seem to repair itself
Phase wires never seem to get warm, not enough to cause an issue... Beginning to wonder aboutthe bearings, though it did not feel like a bearing issue at all

I have been riding in bad weather, so corrosion is a possibility, butI cant think where amd how ir would cause what
I felt

 

[John in CR]

Re the water, I was thinking cumulative plus previous owner, if it was bought used.

Our hubbies are typically centered by a couple spring washers, so they can move a bit left/right. If you have disc brakes maybe it was in a bind to one side temporarily putting some pressure on the disc .

I wouldn't take the wheel off without a repeat or some other symptom like a strange new sound or motor misfires or knocks. If it does happen again then without a takedown you can verify whether it's a phase short, and if so with which wire(s) by shorting them yourself in alternate combos and checking turning resistance.

 

[NeilP]

It was a new motor, and all ok inside last time I looked

I take mine apart in a different fashion to how seems to be recommended....I leave the stator in place and just lift the cover,

Undo the ring bolts, and fit a puller to the disk mounting holes, and lift the cover off...saves the risk of putting it back together again with the magnets snapping it shut.

If you need to get the other cover off, then take the disk brake side off first, then tap the cover off from through the stator 'spokes' leaving the stator inside the magnetic ring hub.
As soon as you put the covers back on it all re centres itself

When I first got he motor, I did expirement with what it felt like with phase wires shorted to each other when not conected to the controller, and with all three shorted together , you do get the 'cogging ' feel when turning the motor...Sensor or sensor less...I cnat see that making any difference to the feel of it when the phases are shorted together.
Still on holiday in Canada till the 24th...so wont be doing more on it till I get home...just wondering if I cna go see Maxwell in Montreal and take another motor home in my baggage...I was 10kilo light on the way out...umm

 

[John in CR]

When I first got he motor, I did expirement with what it felt like with phase wires shorted to each other when not conected to the controller, and with all three shorted together , you do get the 'cogging ' feel when turning the motor...Sensor or sensor less...I cnat see that making any difference to the feel of it when the phases are shorted together.

Simple, if there's a phase short then the turning resistance won't change when you purposefully short the one(s) with a short. If there's not a phase short, then there will be more resistance to turning when you short them yourself. This is just to diagnose whether or not you have a short in the phase wires when you have that increased turning resistance, and if so, in which one(s).

 

[NeilP]

yes, I can see that..if you already have a short ...and make another ...then no change......my cause for worry is the intermittant nature of this...so maybe an axle moving/spacer issue...but it did so much feel like a phase short..yet the motor ran fine...weird

 

[NeilP]

Took the motor apart this morning and the problem became apparent immediately.

Bits of hot glue that i had used to secure the new phase wires. the glue had melted again with motor heat, and run down and then cooled between the stator and rotor...the cogging effect was caused by the balls of glue moving between the edges of the magnets and the slots in the stator laminate where the wire is originally wound when stator is built

 

[dogman dan]

:lol: Funny how what seems so logical on the workbench ends up so bad. Hot glue, perfect!

I've been amazed myself, that zip ties have such a high melting point. The get crispy, but never saw em melt in a motor that didn't have flames shooting out.

 

[NeilP]

Yea...I did have second thoughts about the hot glue when I used it..but the old stuff looked very much like hot glue ....probably a higher melting point type though!!

 

[Ykick]

Probably a good thing you looked inside. Always nice to solve these kinda things...

 

[NeilP]

I have ended up damaging a bit of the green phase wire insulation when I pulled the plastic insert up out of the hub side plate, but apart from that all went smoothly....oh and I noticed a broken spoke