Quality of product: Magic Pie II and III & accessoires

[Sam.Vanratt]

Hello community
after reading a lot about GMs Quality assurance I wanted to collect Infos about the known problems.
My first one (MP3 Front) had: A big blowhole/bubble was in the black anodized part (sideplate) and let a big amount (~50ml) water from pouring rain in and defected the motor and controller until I detected it.
My second (MP3 Front) came with mm thick corrosion on the axle (controllerside) and the following bearing (it was replaced instantly by the german dealer after complaining).
[my third had big scratches in the anodized part of both sideplates which were nicely cached with thick paint; as the package was still orignal sealed (as the others as well) I don't think the dealer repaired it; it was replaced as well; as this was no mechanical/electronic problem I do not count it].

As I do only use one brakeinterrupter (for Magura Hydraulic) I cannot say anything about the addons (Horn, throttle, thumb, light, brake, acculevel, ....) from GM.

I read about:
a) HALL sensors
b) controller complete lockup
c) bearing play
d) Thumb/Twist controller
e) loud humming
f) low Q aluminium chassis (stator and rotor all the same)
[Capital] G) Service, RMA Reaction from GM
h) anything else than the Aluminium casing is liable to rust (screws, axle, washers, nuts, springs,....) [in my case I did replace as much as possible with A4L parts (as it does not cold shut like A2 with Aluminium) or A2 when nothing else was available]
i) 14mm Axle which is very uncommon; a 20mm thru axle/stud axle would offer better/stronger standard forks and therefore more safety

Anything left?


Now: What I like on GM's MP III:

-Interesting design and possibilities
-High efficiency
-controller inside
-High Torque
-minimum ext. cables
-customizable (Controller)
-short High Amp Cables
-integrated cooling

Anything forgotten?

Sam

[Morgen 3Eman]

Hi Sam

You seem to have listed most of it.  It is a shame that such gorgeous design effort is being implemented with such low attention to detail.  GM seems to be throwing away a bright future to keep from spending a few pennies more on the production cost today. 

TTFN,
Dennis

[Andrew]

Design and convenience  does cleverly and  unfortunately seem to come before component quality.   From my experiences the controller in general has always been the weak link in the chain as far as performance and quality are concerned. Most people have at some time suffered small manufacturing/mechanical problems but these usually can be overcome. However, if you are going to integrate a controller in a motor you'd best make it a good one in my opinion.   

[Morgen 3Eman]

Hi Andrew,

The controller in my MP3 was an example of brilliant design doomed by ill-informed management cost cutting.  I believe the failure of two controllers was in large part caused by installation of marginally acceptable, cheaper parts.  I was astounded to find 60VDC rated electrolytic capacitors on a circuit board that is powered by 56+ Volts!  The 5VDC voltage regulator was rated for 48VDC max, but my "48 Volt" battery subjected it to over 56 VDC.  My guess is that the design was done for 24 or 36 Volts, and someone in management found out that it could be used at the higher voltage.  I cannot believed the original designers would have used those components at that voltage.   I wonder if anyone running 24 or 36 Volts has had controller failure in their MP3......

Do the Chinese have a saying like the English "Penny wise and Pound foolish"?

TTFN,
Dennis

[Sam.Vanratt]

Hi
as I modified my first defective one (with the big hole in the sideplates which let water in and therefore destroyed it) with different components I did the following (after I had to completely disassemble it, thanks to good guidance with the foruim here) to catch up with state-of-the-art design:
a) I let a vacuum dip coating of the stator wiring done and a final shaving of the pol heads
b) change both bearings with energy efficient bearings from NTN which reduces loss from (at 50kg load) from 13W to less than 6W per Bearing, unfortunately they costed a lot due to my "I only need one" so each costed me about 30EUR instead of about 6 or 8 when I did as volume buyer; the difference is only measurable under heavy load. The endurance of the bearings should be more than 200mio turns, so enough for me ;-)
c) I coated the SMD upside+downside (not the FETs) with PU to have them shielded from moisture. Because it's a low adhesive version it's easily detachable by just pulling harder on it.
d) I did upgrade the PCB with a thick coating of soldering tin with a pure copper cable on top on all current switching lanes
e) I replaced all external cables as I need only PAS, SerCom, PowerBrakes, ground, 5Vout and Powersupply. The main issue was about cable length and thickness. The original may have a square of max 2mm^2, while the new one is a 4mm^2 with pure copper and for the other 5 signals I used 0,15mm highly flexible signal cable. So I kept the original mechanical brakeout, reducing my external "cable mess" to a minimum
f) I sealed (with a highly    capable to creep PU mixture) both sides of the ext. cable so no water/moisture will come in. That's only to keep corrosion away from the cables. As Germany has become a bit of a wet country (maybe not as rainy as the UK) I wanted to conserve the cabling for a long life span.
g) I let the 14mm wheel be conserved by covering it with some "magic liquid" (from a friend who pimps 1950's cars as hobby) which coates the iron skin with a light blue shimmering; so far it hasn't corroded more (old rust was cleaned before)

What I missed:
a) strengthening the alu stator
b) exchanging the quality limited in-hub controller (which I see as an advantage to have it included in the motor) with an external
c) I did not (what I planned before) exchange the FETs to lower RDSon versions (better n) or higher Voltage versions (which I do not need)
d) neither did I change the standard condensators to solid capacitors with lowESR; it'd have taken to much time (investigation where to get and the right values) & money (   shipping costs mainly) to replace all of 'em
e) I planed to replace the 5V regulator with a high-eff. switching controller. TI and National.Sem offer a few with a huge range (up to 90V in) and n of about 90% with only five ext. components. I need them for my lights and (yes) iphone navigation, which consumes a bit more than the allowed 500mA. As I drive always with lights on, charging (iphone) is not possible. I'd still do it as the replacement would have been always external.

So I think this one would be the best MP3 I could imagine: the efficiency must be (pure estimation!) about 5-10% better, by just adding 50EUR to the component mix excl. the dip coating (must be lower for wholesale). The water resistance is still the same as original, but this was already in acceptable ranges: how the cables are (U) bound is the important point.

Conclusion: The MP2/3 is an exceptional hub motor unluckily hit&reduced by cost management. I own an Bionx as well and I find the MP3 more interesting (apart from the weight) by it's construction. When my second MP3 will have a maintenance needed,  I will surely upgrade it as well!

Cheers and a good and fortunate 2014
Sam

[Gregor]

Sam I've just bought the Magic Pie III. 37 miles and it's screwed already. Kind of pissed about it.
Nice answer all the same. Just some of the muppets like me are skoobied.  Thing is broke. I have not got the nearest clue how to fix the f*%king thing. I'm upset.

[Sam.Vanratt]

Hi Gregor
sad to hear about it. What's exactely not working? Did you open a thread about it? My first one (which I described above) was defective after one night standing in the rain (a about 1cm big hole in the sideplates let water directly flood in). Such a prodution failure should never come out of GM sites, but china is a long way away so no real hope to get a result from them.
That doesn't lower the principle they use, just "a satisfied customer looks different". Without this forum I'd never bothered to repair my first one , but thrown it away as far as possible for such a money (I've ninecont, crystal and bionx BLDCs as well) such a spike in quality management or product itself is poor for the QM departent itself.
In my threadhere only two responded I thought only I had such a bad part, as my second (I owned three) was perfect from the outside (never put it into action, as the available forks are a bit of a problem to me).
Some customers seems perfectly satisfied, so I wanted to know how many and what kind of problems aroused as my first one might be a quirk which could happen.
Look into the head of this thread and look what's most likely:
-no reaction, dead (=electronic)
-no rotation, humming (=mechanical)
-no reaction with the controller (USB/SerCom)?
-load noises while driving (hall sensors)
-buzzing at start (=electronic)


Best open your own thread about it. Most problems have been solved in the forum. From three deliverer (GM, AnTeRa and H&N Motor) only H & N reacted at all and forwarded me to GM direct (who never reacted on anything apart from sales).

Cheers
Sam

[Gregor]

Hello to you Sam. Thanks for your reply. Hopefully the replacement part being sent to me right now will solve my issues.
Gregor.