Magic Pie III Dead

[Sam.Vanratt]

Hello all
after two years of more or less stress free running (about 24.000km yet) my MP3 started to turn as soon as I have plugged it in even when the throttle (Connector 3) was disconnected (about a week ago). Luckily all the time the brake worked. At the same time it could happen it didn't start at all, and after a few minutes it started to start with a certain amount of RPMs sometimes ignoring what the throttle delivered. On last Friday it stopped reacting on anything, just occasionally a short start and after a moment stop.
I first thought about the HALL sensors I often read about while buying the MP3. As I need my bike for a living I needed a replacement (HALL or electronic) so I bought HALL sensors and an replacement electronic (the german company I bought this MP3 closed short after my buy, so warranty was lost and sending a 10kg wheel around the world is more expensive than spending 100EUR for a new electronic). I use the MP3 in a moderate setting with 24V/11A limitation (17A max) so burning the electronic is quite far away.
Anyway I disassembled the MP3 according to David's guidance and when I opened the PCB chamber I've seen corrosion in the lower parts of the chamber + all the electronic (see attached picture).
So now my question: I spend the money OK, I will assemble it again (I'd like to have modified it to the sinusoid PCB) OK, but how could I keep the water out? When I received this  MP3 the axle was already rusted, which might happened when transported from CN to the EU, but this is quite normal for hardened steels. Where did the water get into? The cables had the needed U turn so all water will drop outside. The chamber was insulated with some Silicone and I could not think of anything apart from the axle to chamber tights.
Is there a way to test the HALL sensors as I'm not really willing to replace them when not needed (even when LowQ versions were used).

I expected the internal electronic/composition to last longer even when I'm outside quite a lot, no matter if it rains, droughts, hailstorms or snow is awaiting me. Up to now even the bearings did hold (which was the first thing I expected to brake down).
Cheers
Sam

[Sam.Vanratt]

Hi everybody
Is there no guess what to do? I need to know so I'd assemble it again....

I'll try to contact David at wyh@goldenmotor.com to ask him, but this seems more of a mechanical problem so maybe Li (zhourenli@goldenmotor.com) is my best chance. It's been two years with no contact.
As it seems the old problems (water getting into the housing or the bearings/PCB dying ) is no longer such a problem but mine :-(

Cheers
Sam

[Bikemad]

Hi Sam,

Unfortunately, the MP4 sine wave controller is not compatible with the MPIII and I have already discovered (after wasting a lot of time and effort) that my MPIII wouldn't run correctly with the MP4 controller.
According to GM, the stator on the MP4 stator is wound differently to suit the sine wave controller.

You will need to clean the axle and controller housing as much as possible using a wire brush or Scotchpad etc. to remove the existing surface oxidisation and then brush a thin layer of petroleum jelly over the entire surface of the cleaned metal to help prevent it from oxidising again.

It is almost impossible to seal a hubmotor 100% and the tiniest of gaps will allow water on the outside of the hub to be "sucked" into the motor (through the bearing seals etc.) as warm air inside the motor contracts when the hub cools down. Water from a hose pipe, heavy rain or surface water thrown up onto the motor tend to be the main culprits.

Ideally, a small vent/drain hole should be located at the lowest point in the controller housing to allow the pressure inside and outside the motor to equalise, and also to provide an escape route for any water residue/condensation trapped inside the controller housing.

Take a look at this post and this video for more details on testing the operation of the hall sensors.

Alan
 

[Sam.Vanratt]

Hello Alan
I've looked into Gary's explanation so the MP4 Upgrade is out of question as I needed a solution which was a new MP3 PCB. I already cleaned the housing after I disassembled the chamber. The axle rust was already on the new bought MP3. I investigated two years ago about it as corrosion was (on a 450EUR Hub only) quite out of my quality range. As it seems to me the axle (see the rust traces) was the leak in. The cables have been sealed (I read about 6 month until I integrated the MP3 into a new modeled bike) with epoxy before connecting.
This means I need to solve the suck in Problem. I've seen a spiral tube solution, but as my Hub is quite cool (max 250W are allowed to go into the Hub by german law) with such low wattage. Anyway there's always melting water, humid air which have to go somewhere. As I have a special fork (custom build) and a lot of wiring getting the Hub out is a work done only once a year to change my tires. I'll already used Petroleum jelly on my second MP3 [which was modified from base to top (which I have to check) just as I wrote in my report two years ago] to ease the change of the PCB the next time I might have to.

CHeers
Sam

P.S.: U might want to try an external Sinewave controller. As sensorless it works in delta and star (that's what GM changed) config.

[Sam.Vanratt]

Hello Alan
yesterday I changed the controller which took a few hours as it was quite hard to get the controller evenly into the chamber and afterwards the outer cable into the pit. Set my settings and rebuild the bike. What should I say: it works.
Unluckily the Regen braking is working completely different. I'll open a new thread about it.
Cheers
Sam