Magic Pie loses all power under load at low speed

[Trond]

loses all power under load at low speed. I have tried with more wires and fuses. It cuts out about 5 seconds, then run again. Must ride up to about 15 km \ h before I can twist the throttel full at zero gradient. Charging the battery cuts out when I brake at high speed. Is there anything I can do about this? Otherwise I am very pleased. Have tried with two batteries. 48V lead acid 12a, and 20a Ping 48V battery.

[Leslie]

Hello andto GM forums.

Does the bike feel powerful at high speed under load or does it feel like a slug?

Do you get beeps?

Strange behavior!

Its almost like it cuts out because of high current sensing.  Do you have programmable cable?

[Bikemad]

Its almost like it cuts out because of high current sensing.

Or there may be a high voltage drop between the battery and the controller.

Is this a new problem or has it been this way since the motor was first fitted?

Rather than assume that it's a problem inside the controller, it would help to eliminate the external possibilities first:
If the battery gauge lights start to go out under load, it is more likely to be a voltage supply problem.

If the battery voltage remains high under load and the battery gauge indicates a low voltage, it will be a wiring, fuse or switch problem somewhere between the battery and the controller.

I have tried with more wires and fuses.

What size fuses have you tried, did any of them blow, and were they correctly connected using at least 30A cable?

Are all the joints on the battery leads soldered correctly?
A poor connection on the battery supply cables could result in a large voltage drop and if this occurs, it usually produces lots of heat.
Is there any sign of the battery leads getting warm at any of the connections while under load?

Charging the battery cuts out when I brake at high speed.

What size wheel is the Pie fitted into and how fast is "high speed"?

When replying to these questions, please try and give us as much information as possible.
For example, if it was a front Magic Pie fitted to a recumbent tandem with 6 foot battery cable extensions made from bell wire, this may be extremely relevant.

Alan
 

[Trond]

First used 20A fuse, Then used 2*20A fuses. Larger wiring then original Pie. These mods gave no change. The problem has allways been there and must be inside the magic Pie. The Pie vas bought in december last year. The indicator allways says full battery. 26 size rear Pie with no extra cable. Top speed 45km\h. Powerfull at high speed. Never heard beeps. No programmable cable. No hot cables.

[Leslie]

Maybe your Pie doesnt like to go slow.

Battery and fuses and cables are all good.  Lotsa  power on hills at higher speeds.  Doubtful any user error is to blame.

Power cable to motor to internal controller may be defunct, following Alans suspicions..

Coils flex under high loads, very rare but if they short to stator on two phases, hmm almost impossible..

Must be controller dysfunctional.

Where did you buy this motor?

[MonkeyMagic]

Wow this is funny... (surely not at your expense Trond!)

I changed my wheel to 36v last week, noticing a great change in torque; near no notice of speed loss.

The wheel was originally set at 24v when I bought it (few months back), I already had a controller cable so I immediately set it to 48v when I received it.

Anywho I took it on a 40km+ test ride last night that had some decent but achievable hills. The last 20km's it rained, the last 10 of that my bike throttle was intermittent just like your symptoms.

So my immediate reaction was that I hit the overload protection on the BMS (that's what its for right?) - now that I thought about it, it would be good for GM to limit the software when changing the wheel voltage. I'll get the meter cranking at run some numbers me thinks..

It's no worries at full charge.

What I am gathering is that the software really doesn't apply a different voltage to the Pie, but perhaps limit the current supply to match the battery range (36v GM battery having higher max output than 48v)

So maybe 2 test options here?

1. Get or do you have a USB Controller cable?
2. See if you can get a 48V battery that has a max current output of ~50+ amps

I hope you get your pie chomping hills again soon dude.. No offense but those ping batteries generally have terrible max outputs - I would check the BMS max outputs fo sho

cheers

[Leslie]

Hi Monkey I ordered some pie and a wait for mine to be packed and delivered.

Yes the voltages in software are really set for LVC on the controller.  Its like a double protection.

Yes the BMS why didnt I think of that.

On a side note.  

I also pick up two of those latching relays you posted and going to give them a go, A good thick 60 amp switch like that should do well.

How did you arrange  the latch on latch off for that relay?

Ohh and strange you lost torque and not speed, '

Motors are generally wired up to give more torque with amps and speed with volts, in some instances in motor windings this is not a solid case.  There are plenty of high voltage motors that don't need amps to wind up ship loads of torque.  

The pie will give more torque with volts but generally speaking it should be losing speed when you  lower  the voltage.

[Trond]

I bought it straight from GM China. Exactly the same problem with a new lead acid battery 12A. 'm Pretty sure that there is an overload protection in the hub that is too sensitive. I do not think I can connect PC to my Magic Pie. The Pie is too old? Wonder if I can change the electronics in the hub? Is it possible to buy it loose from GM? Thank you for helping me. My English is not very good, but hope you understand what I write and mean.

[Bikemad]

Yes the BMS why didnt I think of that.

If the BMS was cutting off the power, I would expect at least one or two of the battery gauge LEDs to go off at slow speed! (All LEDs should go out if the BMS cuts out when the throttle is applied while the bike is stationary.)
But as:

The indicator allways says full battery.

This would seem to indicate that the required battery voltage is definitely reaching the Magic Pie's power lead, ruling out a problem with the switch, battery cables, connections and fuses etc., but a voltmeter would confirm this more accurately.

If the LVC on the pies controller cut in too soon, this could cause the motor to cut out and the battery gauge lights to remain on, but as they are usually preset for 24V batteries, this should definitely not happen with a 48V battery.

I'm Pretty sure that there is an overload protection in the hub that is too sensitive. I do not think I can connect PC to my Magic Pie. The Pie is too old? Wonder if I can change the electronics in the hub? Is it possible to buy it loose from GM? Thank you for helping me. My English is not very good, but hope you understand what I write and mean.

The current limit on the Pies does not cut the power completely, it just prevents it from going above a preset limit.
My Magic Pie won't go above 20.18 Amps at maximum motor load (steep hill starts from stationary) and my 25.9V 10Ah LiPo pack is rated 200Amps continuous and up to 300 Amps max!

If the controller is faulty, you may be able to get Tom (zhourenli@goldenmotor.com) to send you a replacement controller under warranty.

Alan
 

[Trond]

Not received a response from GM. Does anyone know which part inside the electronics that control the max amperage or voltage consumption? That must be what makes the engine cut. Maybe I can change the part?

[karen]

Do you have PAS fitted? Mine act like that.... when PAS is in use....

[Trond]

No Pas fitted.

[MonkeyMagic]

Hey just an update here..

Today before I put the front Magic Pie on I went for a ride to the supermarket.

Since my post here [where my hall sensors failed in the rain]  I've been riding it with the hall sensors as disabled as I could think of getting them without disconnecting the wires inside - I set the phase to 60deg in the USB link. This made my pie beep immediately on startup so I thought that was good to leave it in sensorless mode.

Anyways before I left, I turned on my bike and since that night, what I remember is when I goto hit the throttle absolutely nothing happens. When I hit the throttle with the bike stationary it jerked then beeped so it prompted me to reset the phase back to 120deg

My hall sensor is back!! woohoo so I didn't know if that was a case of it being misaligned from a bump, or I am thinking definitely rain that has finally evaporated from in there. It was a really rainy night and water would have seeped in there a little bit. So that ceased up my hall sensors and lucky nothing happened to the controller. I could have tried this a few weeks back as in a few days after that rainy night. I can remember leaving the wheel in front of the heater for a long time to even get the wheel to work again....

So I took off to the supermarket like a happy Monkey without having to pedal or move the bike on takeoff On the way back co-incidentally the throttle was cutting out again!! Here I jumped straight to thinking of the hall sensors but it was a nice sunny day. Anyway I pulled over and went to pull the plug out of my battery and noticed the connection was not in all the way.

I think this is a VERY important thing to check here

Make sure your battery power connector is firmly put all the way in the socket, also if you have soldered the wires yourself made sure you used a 80w or similar soldering iron to make a really good connection.

Could very well be the whole reason, because I had the EXACT same symptoms as Trond.

I then removed the socket, waited about 20 seconds for the power to diminish, then I firmly plugged the connector all the way into the battery.

Upon takeoff I noticed a massive increase in power as the connection was much better and overall my pie felt much healthier.

Trond, check your power connections including the pins inside your anderson connector (the big one that plugs into the battery) if you use a GM battery as it could very well be the problem.

Hope it is as it's been a while since we heard from you

[Cornelius]

I think you got a good point there MM...

But I would take it further...
Originally, my 36V, 16Ah GM battery had the + wire inside the battery wired via the key switch - I think this is still the case on all gm batteries...

Many of us have experienced the spark that occurs when connecting the main power cables to the controller with power on the cables, and that spark occurs regularly each time one turn on the key switch. I believe that the contacts inside the key switch are getting worn/dirty over time, and would be a source for power loss.

I myself have resoldered the inside of the battery so that the power plug have full power all the time, and i've soldered a third, thinner + wire via the key switch, which goes to the thinner + wire on the controller.
This is the way it should have been made from GM, because this way, there's a better path for the power; less wear inside the key switch, and this is the only way to make the anti-theft alarm works...

[Leslie]

If the controller remains connected to the pack at all times, the controller draws .08 amps/hour.  80ma.

24 hours a day * .08 = 1.92AH amps per day.

7 days * 1.92 amps per day = 13.44 AH per week.  That's your 12 ah pack flat

13.44 amps per week * 4.3 weeks in a month = 57ah a month.Thats your pack finished.

There may be a reason GM makes the anti theft disabled now.

I believe LVC occurs if the pack becomes 10% out of balance.  It is popular belief that if an LI pack is discharged to 70% DOD this can make the pack more out of balance than usual.

Leaving the pack on the charger for long periods of time like three days or more  is recommend when you discharge the pack below 70%.


If you're using your bile and often do deep discharges, leave the charger on all the time to allow the cell to rebalance even if you don't use for a few days it may be good to just allow the BMS to bleed high cells off and allow the low cells to catch up.  The pack can live on the charger in many situations.