Magic Pie 5 build

[Bikewrangler]

Hi. Jim from Norway here. New to the forum (just found it) but have built a few e-bikes before this v.5 (current project).
The bikes before have completed swiftly (1 day) and sold as soon as "the new version" was available. I now have 2 main problems.
1) Due to a battery exploded on an airplane (somewhere) my shipment was delayed and I ended up getting my parts well into the fall. I decided to put the build on hold until spring. I charged the battery and stored it in my cool and dry office.  This is a sliver bottle battery 36v. Now the battery does not seem to "work". When I press the button on the battery it shows "full" (all green lights light up). I guess I should have recharged the battery a few times over winter. Is this battery ready for the scrap heap? Is it a matter of swapping out some or all of the green cells inside? Is it possibly a dead BMS? in that case where inside is it and where do I get a new one?

2) At first I thought it was a dead controller, so I got a new one (with Bluetooth). Managed to break one of the spade
connector tabs on the new controller, way to tight of a fit... Got a new 36v battery, found the old controller to be ok when I connected to it via USB (with the new battery). Now I`m all wired up but when I touch the throttle the wheel
seems to "arrest" itself. I can hear the motor "fire" but the wheel does not turn. If I "flick" the throttle (thumb) the wheel tuns a tiny bit but stops. I have tried to "kick start" but no help.

Hope anyone can help me troubleshoot. Thanks

[Bikemad]

Hi Jim andto the forum.

1) As the battery is still showing full, the cells may all be good, even though it has not been used for some time.
Have you checked the output voltage from the battery using a multimeter to see what the voltage is?
It might just be a poor connection within the battery holder/switch that is no longer allowing the voltage/current to flow out of it.

2) As you have replaced the controller, it is possible that the three thick Phase wires (Yellow, Green and Blue) may not be connected to the correct terminals on the back of the controller. If these are not correct, the motor will try to "arrest" itself.

If you took a photo, or made a note of how they were originally fitted, it is possible that the new controller (especially if it is a slightly newer version) may use a different configuration on the Phase wiring compared to the original controller.

Were your Phase wires connected in the same configuration as the one shown below?



Hopefully it will be something very simple.

Alan
 

[Bikewrangler]

Hi Alan. Thank you so very much for your time. You seem to be the "go to guy" both here and at Endless Sphere.
I`m a bit of a McGyver when it comes to mechanics, electronics...not so much
This was the first version motor and controller of the MP5 with USB (no Blu-tooth).
As the controller came out, being the first time dismantling, it kinda popped off ripping wires off their respective
spade connectors. The connectors have since been fixed. I assumed that all controllers had the same phase configuration?
(yellow, blue, green) the same as in the photo? Do you know of any other config?
Thanx again for help

[Bikewrangler]

You where right. I switched the yellow and green phase wires and motor is on
When I test the downtube silver 36v battery I get 38v (directly from battery and from 4 pin connector black/red leads).
When I press the battery button when not connected it shows 5 red dots. Then when connected to the motor/harness,
the 5 dots light up momentarily then fade out. When I try to measure the output whilst connected to motor I get 2v.
The display nor the lights light up. When I try to charge the battery it shows green (fully charged).? any ideas?

[Bikemad]

I assumed that all controllers had the same phase configuration?
(yellow, blue, green) the same as in the photo? Do you know of any other config?

When I try to measure the output whilst connected to motor I get 2v.
The display nor the lights light up. When I try to charge the battery it shows green (fully charged).? any ideas?

It could the BMS that is cutting the power under load because the voltage on one of the cell groups has fallen too low.

You would need to check the voltage of all of the cell groups to see if one is very low compared to the others.

It could be also a poor contact somewhere within the battery that is simply failing under load.
You would need to check if the battery voltage going into and coming out of the BMS is approximately the same (~38V).

If you have 38V going into the BMS and only 2V coming out, the BMS is responsible for the voltage drop (either intentionally because a group of cells is too low or unintentionally because the BMS is faulty)

If you only have 2V going into the BMS, there is obviously a problem with one of the connections (or a faulty group of cells) within the pack.

Alan

P.S.

This was the first version motor and controller of the MP5 with USB (no Blu-tooth).

MP4 was the first Magic Pie produced with a vector controller (but no Bluetooth support).
The MP5 is basically the same motor as the MP4, the only difference between the two models is the newer vector controller that supports Bluetooth connectivity via the plug in dongle, and this is what defines it as being the MP5.
 

[Bikewrangler]

Hi again. Got the motor working fine but it cuts out at high throttle (I`m assuming due to a weak battery, meant for a smaller motor), then comes back on again after
5 seconds. Now I would love to get my brand new battery from GM china to work.
Got the battery open, but before I start dismantling to test BMS/ cell groups etc
I found a small "bit" on a wire on top of the BMS that looks damaged (see pix).
Could this be the reason my battery shows 38v but drops under load?

I did charge the battery for 12 hrs when I got it, that is I woke it from deep sleep,
but then left it unattended for (I suspect) too long. I think I`t must have dropped
below some cut off point? Any way to revive this without taking out each individual cell and charging them?

[Bikemad]

That damaged item appears to be a temperature switch that would cut out if the temperature of the 5A resettable polyfuse (the large square component it is attached to) gets too hot.

I'm guessing this is on the charging side, as a 5A fuse seems a bit low for the output current, therefore if the temperature switch has failed, it is possible that the battery will not be able to charge.

The BMS should have a B- terminal that is connected to the negative side of the battery (might be where the thick yellow lead in your photo is connected).

Check the voltage between the B- connection and the red power output connection, and then compare it to the voltage between the P- and the red power output connection.

It might be worth temporarily bridging the P- and B- terminals with a piece of wire to see if it then starts to charge. 

Alan

P.S. 38V is pretty low, but should not be low enough to have damaged any of the cells in the pack. It should charge fully to ~42V if the charger and BMS are working correctly.