Magic Pie 4 pulses motor, will not run continuously

[Aeberbach]

I have a MP4 with 36V battery, nothing connected but the throttle. Nothing is shorted. When I turn the battery on I get three lights on the throttle indicating full battery power. If I twist the throttle the motor pulses on but only for a short time - then it will do nothing until the battery is power cycled. So far that's all it does. I have not modified anything. If I connect the two brake levers and the red/green button thing (what does that do anyway?) there is no change.

I have not yet been able to connect to the motor by USB either. I got the latest software from GM Canada, watched the video showing how I should see the CH340 device in device manager (OK) and then run the software, it should time out with the battery turned off then magically connect when the battery is turned on - but it does nothing.

Anyone have tips on what might be causing the motor to only work for 0.5 seconds per power cycle?

[Bikemad]

It is possible that the controller could be set for 48V and the voltage of the 36V battery is dropping too low when you try to apply power.

You really need to get the USB lead working so that you can check (and most likely have to adjust) the battery voltage setting.

If you have access to another PC or laptop I suggest you give that a try and see if it is any different.

Alan
 

[Aeberbach]

That seems like a good theory. But I can't connect to the motor via USB to check it.

Here's a link the video of what happens when I try: https://www.dropbox.com/s/pbg1z3uesks9if5/NoConnect.MOV?dl=0

The USB cable looks exactly like it should, 5 pins, no pins bent. CH341SER.EXE installed just as shown in multiple threads here.

I tried it with the default setting of COM3. I have tried changing the COM number to 5 (same as in the GM CA video). I have tried this multiple times, tried after charging the battery fully overnight, tried after resetting the computer, after plugging in the USB after reset and with the USB present at startup etc. I've tried this on a virtual machine (Parallels) running Windows 10 pre-release and Windows XP, and on Windows 8.1 on a Windows PC (where the video was made).

Any other suggestions? I notice I don't get the exact same error message as shown in the Golden Motor video for the timeout.

Does anyone know the colors of the serial lines connecting to the motor? I could try my KeySpan USB serial adapter and make another serial cable.

[Aeberbach]

The 48V setting is almost certainly the problem. I still cannot connect to the motor via USB using the instructions described here and shown on video but I can read its current settings.

If I start the software with the battery off and click the "upload" button nothing happens. If I turn the battery on and click "upload" then I get the tables populated and the value that is set in "Nominal battery voltage (V)" is 48! I am confident this is an actual reading from the motor because it receives nothing when the motor has no power but reads this value consistently when it does have power.

What I can't do is set this to 36V because I can't write anything back to the motor. No matter what I try, I cannot connect correctly and the "download" button does not work in this state either.

At least the motor shows some signs of life. I am beginning to think the USB cable might be at fault - can read but not write.

Is there any chance the motor might be refusing to even communicate because of this 48V issue? I could probably rig a 48V supply temporarily - it won't be asking for 25A unless there is some throttle applied.

[Bikemad]

The 36V battery will not affect the ability to program the controller as I can successfully program mine to any of the three voltage settings using a single 4 cell LiPo pack which is only 16.5V.

If when you connect it is populating the values in the software interface program then the controller is definitely transmitting data, but like you say, it sounds as if it may not be able to receive the data.
This could either be a faulty USB lead or a faulty controller unit (or wiring harness)

If you can rig up a 48V supply and the motor does not work correctly it will probably be the controller that is faulty, but if the motor does work correctly on 48V it will still be difficult to know which of the two components is at fault.

Obviously another USB lead would be the easiest option to try, but it could still be the controller.

If you bought it from a local dealer I would suggest returning the USB lead and asking them to check it out and send you a replacement it if it is found to be faulty.

If the lead is good then I think the controller will need to be replaced.

Alan
 

[Aeberbach]

I really hope they're at least giving you some free kit Alan! I'm in touch with a Golden Motor engineer now and I hope we soon get to the bottom of this. I'll update if there are any tricks that fix the problem.

[Aeberbach]

I'm happy to say I got some beta software from GM and I was able to program the motor for 36V - my bike works. I don't have to pedal any more! If you are having troubles programming you should definitely get in touch with Golden Motor support. I can't distribute what I have but I do hope it is released very soon, it does not even require the timeout/power-on dance to connect.

I'm running the motor at 15A for now and after my 18km commute I have around half of my 8Ah battery left though it is hard to tell because the LEDs are not a very precise measurement. I charge the battery during the day so it always has plenty of range.

Unfortunately my bike frame is not designed to use a derailleur at all so I am going to need to make a hanger or modify a derailleur hanger designed for some other bike. With only the supplied 6-speed cassette - and I strongly advise everyone who orders to instead get the 7-speed - I can only select one cog, by using a chain that is exactly the right length - if you like, it's a single-speed with a cassette. I easily exceed the speed that I can pedal using the motor, and I would prefer to be able to keep the pedals engaged with the drive even at top motor speed. With the hanger made and the addition of a cheapish derailleur and shifter this will be a very good commuter bike and also not a complete disaster if I lose power for whatever reason.

The reason I recommend the 7-speed cassette is that there are a few 7/8 speed derailleurs available for under $20 from various online stores - but I saw none intended for 6 at all, and using a derailleur on a narrower cassette may introduce problems if the restricting screws cannot restrict the range of the derailleur to the narrow range correctly. Also there are very limited options for 6-speed shifters - twist only as far as I can tell, no triggers. There are definitely 6-speed setups around but they tend to be fitted to kids' bikes rather than available as spares via retail.

Apart from the gear modifications I need to do two other things - one is to attach microswitches to my brake levers to enable motor cutoff/regenerative braking. I am not able to use the supplied cable brake levers because I have 160mm hydraulic disc brakes front and rear. With the extra weight of the motor and battery I would not give these up, and I don't know how anyone rides rim brakes in the wet on an electric bike, with a bag or two and rider that must be well over 100kg moving at 30km/h - it certainly is for me. I have ridden another eBike with a smallish 250W motor, no bags, and the rim brakes are just not strong enough especially with levers that can be generously described as mediocre.

The last job is to tidy up the wiring harness. As supplied the cable is too long, has connections that I will never use (horn etc.) and uses connectors that I don't exactly trust. I'm looking into IP67-rated connectors and will be rewiring for neater appearance and waterproofing. I really do wish the GM controller was re-wireable but the whole thing appears to be potted in resin, I will need to cut off the cable fairly close to the controller and use a better connector to mate the whole thing to my new wiring harness.

[Lewis Balentine]

.... With the extra weight of the motor and battery I would not give these up, and I don't know how anyone rides rim brakes in the wet on an electric bike, with a bag or two and rider that must be well over 100kg moving at 30km/h - it certainly is for me. I have ridden another eBike with a smallish 250W motor, no bags, and the rim brakes are just not strong enough especially with levers that can be generously described as mediocre....

Quick stops can be achieve by steering into a nice pothole --- of course it is a bit hard on the front rim.

[Aeberbach]

OUCH! I hope you were standing, rather than sitting on the saddle at the time!

If anyone is interested in the connectors - I have found Molex MX-150 line for the battery-motor connection, and Conxall/Switchcraft Micro-Con-X for the low voltage connections. All are rated on the lower end of submersible so they should handle rides in the rain. Unless I find an even bigger pothole than Lewis did...

[Bikemad]

I have found Molex MX-150 line for the battery-motor connection, and Conxall/Switchcraft Micro-Con-X for the low voltage connections. All are rated on the lower end of submersible so they should handle rides in the rain.

They should be able to cope with the rain, but will they handle the battery current?

The MX-150 contacts are rated for 22A which may be able to cope with a Smart Pie with the current set at the suggested 18A but they might struggle with the 30A drawn by the Magic Pie.
You would need to use a "1 by 4" connector and use two pins for each of the battery cables to halve the current load on each of the pins.

I also suspect that fitting the connectors to the wires might be a pain if you don't have the correct crimping tool.

Alan
 

[Aeberbach]

Yes I am very familiar with the pain of crimping when you don't own the Molex $682 crimping tool but over the years have become adept with tiny pliers 

I'm finding absolutely no need to pedal at 18A (MP4, 36V) so I don't think I will increase current any further and might decrease it when my gears are sorted. With my 8AH battery it should probably stay at around 15A anyway - I do have four circuits set aside for power.

[Lewis Balentine]

OUCH! I hope you were standing, rather than sitting on the saddle at the time!

I was airborne over the handle bars 
but I walked away and now pay closer attention to the pavement.