Magic Pie only running at 17mph?! 48v 12ah battery seems to be working

[magicaffair]

Hi all, I have a problem. Just bought a premade bike with Magic Pie 2 kit on it.  Motor is very juddery at low speeds and makes a groaning sound until I get going fully... and when I do I can only achieve 15-18mph full throttle... it feels gutless... the internal controller crapped out so the chap I got it from wired an external GM controller under the seatpost... I've checked all the wires and they seem correct according to the config sheet I found online for the controller. I'm wondering if there's a problem with a hall sensor as I can't throttle from standstill (bike needs to be rolling before motor kicks in) V frustrating I have a Magic Pie 2 with 48v 12ah GM battery... the battery has charged in 4.5 hours and still pulling after 5 mile run around block.. just bloody slowly?!?!

Can anyone help or had this problem... juddery and noisey til I'm going, then low top speed. I'm wondering if the controller came programmed to limited speed or something? I don't have a usb cable and can't seem to find one in uk anywhere, if this is the problem?? You guys here seem to know your stuff, so I'm hoping there's a saviour out there... I used to have a 500w 15ah kit which kicked arse (27mph) but bike was stolen  always wanted Magic Pie now I'm gutted!

Just to add, i've tried unplugging the hall sensors from the external controller, the motor wont work at all... even when pedalling?? Very confused

[DirtyGinge]

Hi there

Ive seen this before, on a mac motor, where the motor takes a lot more amps than it should also...is it an external controller, and if so, are the external phase wires hot ...shounds a bit like a bad gearbox , basically the wiring configuration is wrong.....yellow is not yellow etc.....

where in the uk are you based ?

[magicaffair]

thanks... it is an external GM controller (silver type with heatsink) where exactly am I looking for the gearbox wiring? is this connected to the controller, or from the battery or motor? Shall I try just swapping round the wires? if so, which ones? thanks in advance for your help 

[DirtyGinge]

As pm'd. I'd try the hall sensor wiring......

There is a diagnostic computer available, which if used right, saves hours of wiring changes

Edward@Lyen.com ....ask for details

 

[Henry Chang]

 
I guess there are some thing wrong with your MP2 motor,your motor is very juddery at low speeds and makes a groaning sound, this is abnormal,maybe so the internal controller is burnt out. Then you change the external controller, believe that it is good.

"I've tried unplugging the hall sensors from the external controller, the motor wont work at all... "pull out the plug, why not the motor does not work, even if the hall sensors is bad or not receive signal, the motor can does work without the hall, you mention to judder and low speed ,I guess the motor phase failure.

[Morgen 3Eman]

Hi Henry,

That is a good point!  If one of the phases were not receiving power, leaving only two phases with excitation, it would run pretty lousy!  It would be easy to check out with an Ohmmeter.

TTFN,
Dennis

[dallasdick]

hey guys, if this motor has an external controller did you check to see if the previous owner has been inside the controller with a soldering iron?  I experimented with an old internal controller by building up the shunt material to take more current, the torque was unbelievable but I couldn't run it from a standstill, had to pedal up.  The growling and vibration sound is unnerving until you get to around 12 mph then it starts to smooth out.  I considered the experiment to be an abject failure and removed to extra material.  It then performed as it should.

Moral:  If anyonw screws around with the shunts in the controller, it will cause this affect on the pie, making it shaky pie.

[magicaffair]

Hi I have checked all the phase and hall wires,I removed a section of suspect phase wire which looked like it had seen heat.  Wheel still doesn't run wel, vibrates and loud sqealing noise until 12mph then smooth until 19mph when loud groaning starts again, I can't get above 20mph even with pedalling it's driving me nuts!!. Have tried every combination of hall /phase wires but none work unless wheel is spinning first, even then it is still underpowered. Haven't looked inside external controller that is my next port of call I think. What am I looking for in there? How do I check the fets? Is there any tell tale signs that the controller is duff? When I unplug the hall sensors the motor doesn't run at all... i'm told it should do without the hall sensors connected. Really don't know what else to do now...

[magicaffair]

Hi all, Have a pie with external golden motor charger.  I have checked all the phase and hall wires,I removed a section of suspect phase wire which looked like it had seen heat.  Wheel still doesn't run well, vibrates and loud sqealing noise until 12mph then smooth until 19mph when loud groaning starts again, I can't get above 20mph even with pedalling it's driving me nuts!!. It's like I have 2/3 power.  Have tried every combination of hall /phase wires but none work unless wheel is spinning first, even then it is still underpowered. Haven't looked inside external controller that is my next port of call I think. What am I looking for in there? How do I check the fets? Is there any tell tale signs that the controller is duff? When I unplug the hall sensors the motor doesn't run at all... I'm told it should do without the hall sensors connected.

I tried to take the pie apart today, but due to the external wires coming from hub cant get the outer plate right off... from what I could see inside looked like there was some corrosion on the outer magnets all way round, but aprt from that seemed ok.  Would this make any difference? Wheel runs smooth between 12moh and 17mph so I figure the pie itself is ok and must be wiring or controller issue. Really don't know what else to do now...

[dallasdick]

you need to get the pie cover off and inspect the motor casting for stress cracks where the spokes meet the center hub. Also if your pie has seen water inside you might want to blow it our with air and use some steel wool to knock off any surface rust on the magnets face and the motor plate faces but don't use any lubricant or rust remover on it.

It sounds like your used pie has seen some good times.  Now is a good time to clean it up while hunting down the vibration source.  Did you look into the controller yet?

[magicaffair]

had the controller open this morning, no visible signs of blown fet or any bad soldering... so back to the drawing board... no idea where to go now... short of rewiring the whole thing from scratch I'm stumped! Spokes inside the pie look ok no sign of stress cracks. Only thing visible to me is rust on all the outer magnets inside the motor... would this cause the terrible performance I'm getting?

[magicaffair]

I've tried to show the wiring to external controller as it looks - it's chaotic in there - I'm hoping somebody may notice a mismatch somewhere?  plus do the phase wires need to be thick as they are carrying lots of juice? I am lost with this as there is so much going on here. Motor seems ok like I said, but does have a fair bit of rust on outer magnets, would this cause bad performance? Thanks guys I really want to solve this

[Bikemad]

If one of the phases were not receiving power, leaving only two phases with excitation, it would run pretty lousy!  It would be easy to check out with an Ohmmeter.

Hi I have checked all the phase and hall wires,I removed a section of suspect phase wire which looked like it had seen heat.

Did you measure the resistance between the three Phase wires (Green/Yellow, Yellow/Blue and Blue/Green) with an Ohmmeter as Dennis suggested, if so, were they all similar readings?

If you don't have an Ohmmeter, you can carry out a simple continuity check by disconnecting the phase wires from the controller and then shorting together two phase wires at a time with a paper clip between their connectors and then try to turn the wheel, which should be very lumpy to turn.
Do this with all three combinations (Green/Yellow, Yellow/Blue and Blue/Green) and check that the force required to turn the wheel is similar for all three combinations.

If you find that only one combination causes the braking effect (eg. Green and Blue wires shorted together) then there will be a break or poor connection somewhere along the other phase wire (Yellow in this instance).

If all three combinations produce the same amount of braking force, I would say your problem is being caused by the controller.

I am not able to try the following, so I don't know if it will actually work, but it might be worth a try (assuming the above test gave similar braking/resistance):
Try running the motor with just two phase wires connected at the controller end and see if it will still run as before with each of the three combinations (Green/Yellow, Yellow/Blue and Blue/Green).

If you find that it only runs on one of the three combinations (eg. Green and Blue), but runs even worse than before,  then it could indicate a problem with just one of the MOSFETs on the disconnected phase output (Yellow in this instance).

If you find that it runs exactly the same as before, but only on one of the three combinations (eg. Green and Blue) then it could indicate a problem with both of the MOSFETs (or the low level switching circuit) on the disconnected phase output (Yellow in this instance).

Do the phase wires need to be thick as they are carrying lots of juice?

If the phase wires are too thin it will cause a large voltage drop between the controller and the motor which in turn will cause the wires to heat up under load. If the wires are getting noticeably hot, then they are too thin and should be replaced with heavier duty cable.

Motor seems ok like I said, but does have a fair bit of rust on outer magnets, would this cause bad performance?

I don't think that rust on the magnets is causing your problem, I suspect it is more likely to be a phase wire problem or a faulty controller.

Alan
 

[dallasdick]

had the controller open this morning, no visible signs of blown fet or any bad soldering... so back to the drawing board... no idea where to go now... short of rewiring the whole thing from scratch I'm stumped! Spokes inside the pie look ok no sign of stress cracks. Only thing visible to me is rust on all the outer magnets inside the motor... would this cause the terrible performance I'm getting?

If you have rust on the face surfaces of the magnets it can affect performance as the rust can inhibit a good field from being established.  Use steel wool or sand paper of no less than 220-320 grit to clean rust off magnet faces.  Be absolutely certain to blow or wipe out any dust generated by this action.  I don't know anything about the GM external controllers but I do know controllers have shunts and if they are modified they change performance characteristics, sometimes dramatically. 

[Bikemad]

I've just been looking at your photos, and the bullet connector on the Blue Phase wire does not look right.
(See attachment below)

It would suggest you check this first to make sure it has a good solid connection.

Alan