Author Topic: Performances Magic Pie  (Read 38925 times)

Offline Denis

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Re: Performances Magic Pie
« Reply #30 on: February 06, 2010, 07:16:42 PM »
I received a new 48v 10ah battery and I immediatly tested with my Magic Pie kit but top speed is only 30km/h  :(  :(  :(
I think 45 km/h, as delcared from GM, is too optimistic! I'm not happy at all!!!

Rider + bike weight ca. 100 Kg 26'' rim

Offline Hardcore

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Re: Performances Magic Pie
« Reply #31 on: February 06, 2010, 08:38:03 PM »
how did you measure ?

Offline GM Brazil

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Re: Performances Magic Pie
« Reply #32 on: February 06, 2010, 10:09:46 PM »
I've been doing some math homework with the MP test data and you should got maximum speeds close to this chart annexed. The maximum speed are where the curves intersect. This calculation is for 26" rim with 1.5" tire.

« Last Edit: February 06, 2010, 10:11:48 PM by Yacamim »

Offline ggielen

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Re: Performances Magic Pie
« Reply #33 on: February 07, 2010, 07:05:53 AM »
ps.: If anyone is curious I can explain the math/engineering behind the calculation :D

It is easy to change the formulas and add the % of the hill so you can know the power you need or even if you bike is able to climb that "steppy" hill you know with your weight.

To validate this spreadsheet I compared to some data from here and ES (data from CA or Wattup for example) and is showed very good approximation with the range and cruise power consuption!

If you could explain the engineering behind the calculations that would be interesting. To me the formula appears to be purely empirical..

Offline Denis

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Re: Performances Magic Pie
« Reply #34 on: February 07, 2010, 07:37:41 AM »
@hardcore: I mesured with a gps on my phone. Is it possible that I received the high torque rather then the high speed?!?

« Last Edit: February 07, 2010, 07:40:22 AM by denis »

Offline Hardcore

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Re: Performances Magic Pie
« Reply #35 on: February 07, 2010, 02:12:17 PM »
i don't think so... do you have a speedo?
hook it up to the rear wheel and put in 26inch wheel, in mm.
then it should get 50km/h I think
if not there's something wrong

Offline Denis

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Re: Performances Magic Pie
« Reply #36 on: February 07, 2010, 07:08:32 PM »
Normally I use the gps when I run with my road bike on where I mounted a speedo and there are no diffrences between data registred from speedo and gps, I sure that the speed registered by gps system is correct. I think there is something wrong with my motor.

Offline Denis

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Re: Performances Magic Pie
« Reply #37 on: February 18, 2010, 12:28:47 PM »
News about my tests: I mesured with a bike computer top speed without pedalling and now I can confirm that with my motor I can't exceed 33 km/h. In my case (is it only for me?) is not true what descibed on GM site, 48v <> 45 km/h!!! I'm not happy at all!!!


Offline Hardcore

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Re: Performances Magic Pie
« Reply #38 on: February 18, 2010, 12:51:09 PM »
denis, I don't know about that weight 100kg? as my bike alone is 30kg. I am 65kg and I am 16 years old.

Offline GM Brazil

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Re: Performances Magic Pie
« Reply #39 on: February 18, 2010, 01:03:54 PM »
With my MP using GM 48v battery I WAS able to reach 44 km/h (I wight 110kg and the bike 28,5kg)

But now I can reach a maximum of 38km/h

I do not know why it was better at the beguinning... I'll do more tests next week.

I doo all this tests at the same place to be sure :D

And my MP really "lost" it's initial juice....

Offline Denis

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Re: Performances Magic Pie
« Reply #40 on: February 18, 2010, 01:13:31 PM »
My weight 72 kg, bike weight 28 Kg, I really suppose that I received the high torque rather than the high speed  :'(

Offline Hardcore

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Re: Performances Magic Pie
« Reply #41 on: February 18, 2010, 03:18:54 PM »
With my MP using GM 48v battery I WAS able to reach 44 km/h (I wight 110kg and the bike 28,5kg)

But now I can reach a maximum of 38km/h

I do not know why it was better at the beguinning... I'll do more tests next week.

I doo all this tests at the same place to be sure :D

And my MP really "lost" it's initial juice....

well, mine got faster but only with about 4 km/h to 5km/h duo the temperature, it's about 0C here in the Netherlands but also my range has dropped

Offline Denis

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Re: Performances Magic Pie
« Reply #42 on: February 19, 2010, 07:19:59 AM »
I wrote to GM to submit my problem, but I did not receive answer!

Offline GM Brazil

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Re: Performances Magic Pie
« Reply #43 on: February 24, 2010, 01:50:37 AM »
I solved my speed issue...

I tested with a GPS and it let me to the stupid conclusion that: I changed my tire from 1.5" to 1.95" and the problem was that I didn't changed the setup of my speed meter... Dumb  ::)

Now it is ok lol  ;D

Offline Bernie

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Re: Performances Magic Pie
« Reply #44 on: March 03, 2010, 11:20:33 PM »
I ordered a 24Volt 16AH Battery with my Magic Pie since here in Australia the law is a maximum of 200 watts. The MP 24Volt combo claims to produce 250 Watts, so I'm only slightly illegal. Yesterday morning, after I putting it all together the night before, I was eager to road test it. Its been extremely wet here lately but in between showers I set off into the hilly suburban streets and then to the long country lane where my grandchildren live on a 30 Acre semi-rural plot.

First reaction was; 'cripes, this has LOTS more power than I imagined, it certainly is NO TOY'. I weigh a little over 100 Kg and it easily coped with all the hills, only the extremely steep ones needed me to help and pedal. The second thing was speed, I'm an old bugger and last year went over the handlebars of a MB which put me on crutches for 20 weeks. My 24 Volt outfit here in the urban locale of a small village on the outskirts of Brisbane, lots of footpaths with the occasional car appearing unexpectedly out of a driveway, who needs to do more than 26 or so Kph?

The other noteworthy observation was the power of the regen brake effect. On the damp roads yesterday I was very much aware the rear wheel could lose traction if the regen 'effect' were used in a sharp corner at speed. Experiencing the vigorous regen effect makes using the actual brakes feel rather dead and lifeless, a bit like stepping on Chairman Mau.

Things that went wrong:

I fitted the Magic Pie conversion to a very old (PINK!) Ladies bike. There is WAY too much cabling and I'm going to have this tidied up by a specialist electric bike shop. I can't do it myself. Also, the deraileur disconnected itself TWICE. I noted this is tapered and I will need to file it flat and maybe get a spring washer to keep it in place. This is the only 'problem' I had and in no way a GM problem. However, I notice the RED light indicating EMPTY on the throttle control shows all the time. It also appears the charger will switch off after 2-3 hours, it gets quite hot. Is this normal?

In summary; I am delighted with this thing, as a kid I lived in hilly Mt Macedon Victoria, I would have given my left testimonial for one of these back in the 1960's. For the approximate cost of registering (let alone insuring) a 6 Cylinder Car in Queensland, I have another vehicle which will be used daily for all the little trips to the bottle shop, my watering hole, the supermarket or hardware shop. It costs SFA to run and maintain, and it gives me the exercise I need and it's fun to ride.

I'm a happy man.