Ordered my Magic pie KIT 17-11-2009 Netherlands

[Bikemad]

Gary,

The throttle signal wire should be White.
The Red wire is the +5v supply and the Black one is ground.

Alan
 

[GM Canada]

Thats probably an even better Idear.

Might go for that one........ Hmm have to order another switch and and a 5k variable resistor then.

Would I need a

-MINI MON0 5K AXIAL
-MINI MON0 5K
-SUPERMINI LIN MN 5K
-MINI MON0 5K
-MINI MON0 5K AX + SWT

Do you need this resisitor with the GM throttle? When I add in this resistor my wheel barly turns. I used a 3.9 it turned very slowly then a 2.2 it turn slightly faster. Is this resistor already in the GM throttle. The diagram says "typically inside the controller" Im assuming they mean the throttle control due to the location of the resistor in the diagram. What if I run it without the resistor is something going to fry?

Gary
 

[GM Canada]

Gary,

The throttle signal wire should be White.
The Red wire is the +5v supply and the Black one is ground.

Alan
 

Actually its green on mine, Thank you though, Now I am struggling with the resistor. Please see my other post.

Gary

[Bikemad]

Gary,

I would try it with the the lead to the diode disconnected, as something must be causing a significant voltage drop across the resistor to affect the speed.

Are you sure the resistor is wired exactly as per the diagram?

If it works OK with the lead disconnected, it might be that one of the C/A's settings is causing it to restrict the throttle.

Alan
 

[GM Canada]

I have tried it that way several times and currently the lead to the diode is still unhooked. Anytime I add the resistor it goes a 10 percent of regular speed. Anytime I remove the resistor It goes full speed. The resistor could actually already be present I'm assuming. Going to test the throttle leads for resistance now.

Yes I'm positive the wiring is as diagram shows.

There is 3.85 volts coming from the lead from the cycle analyst before the diode. So if that is hooked up again it will be fine.

Gary

[Bikemad]

Gary,

It's not your wiring, it appears that the Magic Pie's controller requires more current than the recommended resistor will allow.

I just tested mine with a 4.7K resistor in series and the signal voltage drops from 3.62V to 1.42V across the resistor at full throttle.
This works out at 0.468mA (0.0004658Amp) which, although pretty small, is still too much to allow a usable voltage to pass through a resistor of this size.

For it to work correctly, a much smaller resistor will be necessary, but if it is too small it could overload the hall sensor in the throttle control or perhaps the C/A itself when it tries to ground the throttle signal input in order to override the throttle.

I just tested my throttle with an led and got a maximum of 11mA (0.011Amp) at full throttle (3.62V) which is roughly equivalent to a 330 Ohm resistor being grounded out, but I don't know how long the hall sensor would be able to cope with this load.

A 1K resistor would give a maximum load of 3.62ma (0.00362Amp) which might be acceptable.
If I get chance I'll do some more tests using a variable resistor to see how large the resistance can go before it starts to reduce the maximum speed.

If we had some specification on the hall sensor we could find out it's safe maximum continuous power output, but you would also need to contact someone at ebikes.ca to find out the maximum permissible load on the throttle override circuit.

For technical questions or troubleshooting issues, use info@ebikes.ca

I would try and contact them anyway and see if they have come across this problem before.

Alan
  

[GM Canada]

Gary,

It's not your wiring, it appears that the Magic Pie's controller requires more current than the recommended resistor will allow.

Thanks for testing that Alan

It's not a pie though, its a 48v1000w hub motor. But still the same idea i'm sure. I was thinking the same thing about the smaller resistor. I just picked up an assortment pack. I'm going to go try a 1k right now to see how it goes..

Gary

[Bikemad]

Gary,

I think the controllers are very similar in their design, so I would imagine they use the same throttle signal circuitry.

A 330 Ohm resistance gave a maximum of ~3.25V on the controller side of the resistor, which I would say is full throttle.
This would put a load of ~9mA (0.009Amp) on the throttle and the C/A if it pulled the signal all the way down to 0.6V.(0V Ground + 0.6V Diode) But I don't suppose it pulls the voltage all that way, so the load on the hall sensor should be even less.

Just as a matter of interest, the motor starts working when the throttle signal voltage reaches ~1.25V and will give 3 beeps (indicating a throttle malfunction) if it falls below 0.58V. (Typically 0.82V with throttle released)

Alan
 

[GM Canada]

Hi Alan

I tried several different resistors. It seems the threshhold is around 1.5 k to get the limiter function in the CA to work. With the wheel off the ground it will burst up to 35kph then wander down to 32kph an hold a somewhat steady speed. However, on a test ride this does now allow enough power to get up to 32k, only about 25k. With a 1.2 still not enough power. with a 1k resistor it gets up to 32kph then continues to go higher it went to 37k and still kept pulling. It seems that this method will not work with a GM setup. There is another option for limiting speed using the VI pinout on the CA as a throttle signal input and the TH pinout directly to the controller. This method did seem to work in a breif test but seemed a bit eratic. Further testing is required, but I ran out of time (and beer) to be able to test it fully. I have to put things back to normal for my commute to work.

Gary

[Bikemad]

I have to put things back to normal for my commute to work so I can carry more Beer home from the shops at high speed.

Gary,
 
Did you contact ebikes.ca and if so what did they suggest? I'm sure Justin will be able to come up with a solution.

The actual output is derived from an op-amp on the circuit board, and it is capable of both sinking and sourcing current. In the original Cycle Analyst boards (identified by a lack of label on the PCB) this output was wired directly from the op-amp, so it was quite stiff, but also made the board vulnerable to damage if the Throttle Over-Ride was accidentally wired incorrectly to a voltage source. In PCB revision 7 (labelled DB2 Rev7b), the output line was modified to include a 1k resistor (R6) to protect the silicone. This however means that the Over-Ride line can only source or sink small currents, and if more than a mA needs to be drawn from the output, then resistor R6 should either be reduced in value to a couple hundred ohms, or possibly shorted out entirely.

This could be the answer, use a 330 ohm resistor in line instead of the 3-5K suggested and then solder a small link directly across R6 to bypass it.

It would be advisable to run this suggestion past Justin first, and check that the op-amp can cope with sinking ~9mA max.

Alan
 

[Jazzjerry]

Hello Gary and Bikemad,

I haven't figured the cycle analyst limmiting features out yet either.
I did connect the analyst, but had some problems, Have not realy looked into it after that so gary if you find a solution please keep me updated as well.

I also ended up trying voltage in through the VI pad but this resulted in wheelspin without me using the throttle....
I ran out of beer and out of electrotechnical inspiration. so left it to rest and hoped somebody would pick it up in the forums as wel to inspire me some more. and try again.



JJ

[GM Canada]

This could be the answer, use a 330 ohm resistor in line instead of the 3-5K suggested and then solder a small link directly across R6 to bypass it.

It would be advisable to run this suggestion past Justin first, and check that the op-amp can cope with sinking ~9mA max.

Alan
 

SUCCESS!! THIS IS THE ANSWER!!!

The 330 ohm resistor the diode of any size and the jumper on R6!

Since I have CA_SA v2.11, I didn’t like the way the VI worked on my cycle analyst as it would jump when the key was turned on( a bug in ver 2.11 fixed in v2.2) and there was no cruise. So I went back to the diode and resistor with the above specs and it works great! The cruise even works but is independent of the CA. Lets say the cruise is set at 32k. When you take off you can use the throttle and go up the 32k and it the CA works great, holding you at that speed. If you want to go past 32k you can slow down below 30k or so then give it full throttle hit the cruise button and it will go past the settings of the CA. If you hit the brakes then you have to go below 32k to use the cruise to pass the limits of the CA again. I`m still going to keep my switch for override but I like that you can just give it a boost even when the CA is doing its job.

Anyway its late and I’ll post more about it later but its working great!

Gary

[wattsup]

Last and Worst thing I found is the off center rim and bad spoke job. Why not have the rimm in the middle? And why do I have to readjust my spokes every ride....
Because of the big size of the motor (which I think is cool and nice) the spokes are put under an angle that is not normal for a standard rim. This results in bent spokes and spokethreads and difficulties to even respoke the motor.

I think the only sollution here is to get a rim that has custom angled spokeholes to keep the spokes and spoke nipples in a straight line towards the hub.

Jerry,

I fully agree with the spoke angle problem, which cannnot help to maintain an even tension on the spokes.

Due to the large angle between the spoke and the rim (See attachments below for more details), the nipples cannot seat correctly and as a result of this, the tensile force of each spoke is concentrated on one very small point of contact, instead of being spread evenly around the head of the nipple.

As the nipple tries to pull itself down to seat onto the rim, this single contact point will act as a pivot for the nipple, causing it to bend the spoke whilst trying to achieve the impossible (a fully supported and correctly seated position in the rim).

Unfortunately, the nipple will never be correctly seated in the rim, so it has no option but to spend the rest of its life under unnecessary strain waiting for something to eventually fail.

I suspect the loosening of the spokes is probably due to this:

A common reason for spokes to fail on hub motors isn't because the motor puts extra strain on the spokes, or because the spokes aren't a thick enough gauge, it's because of fatigue failure from spokes that aren't held snug against the flange. If the spoke bend radius is too large or too far from the head, then it can flex up and down at the bend with each wheel rotation, eventually causing it to crack and fail.

This problem has been legendary with overseas built hub motors, and we had some Crystalyte shipments where about half the customers would experience spoke breakage on a recurring basis. Ideally the distance between the head and the bend in your spoke will match the thickness of the hub flange, and you won't have problems. But if not, there are two ways to address the situation. One is to insert a washer under the spoke head. The second way is to lace the wheel in an over/under pattern, such that the spoke tension compresses the bend part of the spoke into the flange.

Please note:
Ideal hub hole Ø equals spoke thread Ø + 0.1 mm (eg. spoke thread on 14G/2 mm measures thread 2.25 mm + 0.1 = 2.35 mm: max. hole Ø 2.50 mm).
- flanges which are too thin and / or hub holes which are too large in which case the spoke angle of 95° could increase to 120°

Correctly mounted SAPIM spokes never elongate. However, an incorrect hub can cause the bending angle to enlarge (elongation of the bend up to +1.5 mm per spoke) and buckle wheels.

- Oversized flanges cause extra pressure on the spoke heads. In consequence, the heads pop off.
- Consider spoke washers

Does anyone else have any thoughts or useful suggestions regarding this subject?

Alan
 

has  this basic engineering problem been addressed and cured yet

[Who42]

has this basic engineering problem been addressed and cured yet

YES The spoke problem has been addressed and fixed