Author Topic: Amp limit Magic Pie 5 kit  (Read 4868 times)

Offline Toeffen

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Amp limit Magic Pie 5 kit
« on: August 01, 2016, 10:27:40 PM »
Hi.
I just wonder what the amp limits are on the Magic Pie 5 kit.
I have the 48v 10ah aluminum casing battery.
The motor is 30 amp max?
I have read both 20 amp and 30 amp on the battery.

I know the default is 25 amp. So that is the recomended.
But where is the bottleneck?
How much can the different components handle?

I might buy a second battery. So if I connect them in paralell, they can give 40 amps. But I guess that will burn the controller?

Any thoughts?


I also wonder what version of the software can change the max rpm higher than 380?

Thor

Offline Bikemad

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Re: Amp limit Magic Pie 5 kit
« Reply #1 on: August 01, 2016, 11:32:08 PM »
Hi Thor,

I use LiPo packs that are capable of delivering a continuous 150 Amps with a peak discharge of 300 Amps, but the Magic Pie's controller will limit the current to ~30 Amps maximum even though the available current output of the battery pack is 5-10 times higher than this.
I suspect the 20 Amp and 30 Amp figures for that 10Ah battery are the constant and peak output figures. If you try to pull more amps than the battery can supply, the battery's BMS will typically cut the power to prevent damage to the battery.
If your battery is not cutting out under load then it is able to supply the required current for the motor.

Using two packs in parallel will provide a slight increase in power and slightly more than double the range. As each of the batteries are only being subjected to half of the current being drawn, the voltage sag will be much less, therefore the power should be slightly improved. 
30A @ 52V = 1560W, whereas 30A @ 56V = 1680w (7.7% extra power at the same 30A current level because the voltage sag is less)

The Magic Pie motors are capable of handling a lot more than 30 Amps for short bursts with a high current controller:



Although I suspect the windings may heat up a bit after prolonged use at higher current levels, but I have not yet seen a Magic Pie with burnt out windings.

Unfortunately, setting the rpm higher than 380 rpm will not make the motor any faster as it only reaches ~360rpm under no load conditions using a fully charged 48V battery with a voltage output of ~58V.

To achieve higher rpm you would need to fit a higher voltage controller and use a higher voltage battery pack.

Alan
 
« Last Edit: July 04, 2017, 11:17:38 PM by Bikemad »

Offline Toeffen

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Re: Amp limit Magic Pie 5 kit
« Reply #2 on: August 02, 2016, 05:51:11 AM »
So both the controller and the battery will stop at around 30 amp without taking any damage. And the motor can handle atleast 50-60 amps?
I may want to increase the wattage later. And then I got 2 options using the Mp5 I already have.
Buy another one on the front wheel. Or change the controller.
Need a new,  or extra battery for both options.
The cheapest solution would be to change the controller. But the built in controller was one of the reasons I bought the Mp5.

I know that it cant do more than ca 360rpm now. But still want to be able to change it :)

Thor

Offline DriftTrike

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Re: Amp limit Magic Pie 5 kit
« Reply #3 on: October 13, 2016, 07:51:59 PM »
Does anyone know if the mp5 software can be hacked to change the max rpm? Maybe a software guru can chime in?

Offline Bikemad

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Re: Amp limit Magic Pie 5 kit
« Reply #4 on: October 14, 2016, 03:38:04 PM »
The maximum rpm can only be increased by increasing the battery voltage or changing the physical layout of the stator windings.

Unfortunately the MP5's internal controller would need to be replaced with a suitable external version if you wanted to use a 60V, 72V, 84V or higher battery pack for higher rpm and faster road speeds.

Alan

Offline OneBadWolf

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Re: Amp limit Magic Pie 5 kit
« Reply #5 on: April 09, 2022, 01:37:26 AM »
Replying to this old thread, because it came up when I googled MP5 max amps out of curiosity. Bikemad was completely correct. At the time the thread was written. I bought a MP5 Vector conversion kit from Golden Motors in 2017. Perfect for my first eBike. With a 52V, 26Ah Lithium battery, 80 Amp continuous 100 peak, I could manage 45-48 Kph.

Switching bikes after 2 years, to a MTB with 27.5 inch wheels, I found a decent 27.5 inch rim, made with 36 spoke holes. Tough to find. I removed the Vector, and installed the Grin Baserunner controller/Cycle Analyst combo, and after a massive amount of experimenting, tweaking, and fiddling with various settings, field weakening etc, with no wind, and a long stretch of smooth road, about 50 Kph. No matter what though, there was at most only half of the off the line grunt the Vector delivered.

After getting rid of the Grin SXXtrunner, I replaced it with a Nucular  (how it's spelled) I had to wait 9 months for it. I don't like waiting. To me, instant gratification takes far too long. It was worth the wait. Right from the motor, I upgraded the wiring to 10 Ga., which required a slightly bigger wire hole in the Pie. It autoconfigured itself, and at 15% field weakening, it jumps off the line, and hits it's max of 57 Kph, in just under 10 seconds. (faster with other riders, I weigh 300 lbs) With the rear wheel off the ground, spinning freely, it indicates 74 Kph. I use a second throttle on the left bar, and can modulate the regen braking, so precisely, it's rare to use the rear disk. Before, regen was for long downhill runs, if I remembered to use it. I also injected 5 Ml. of ferrofluid into the Pie, and the temps are no higher than before, my max temp on a hot day, less than 90C. And I still have a little headroom with my batts max amps to play with, which is how I came to find this thread.

 I have heard rumours that Nucular hopes to establish their headquarters somewhere in Europe, as unfortunately, they currently are in Moscow. Obviously, their production, due firstly to COVID, and now, to the terrible events in Ukraine, is very very slow. Estimated at more than double what I experienced. Even still, they managed to put out an update to the firmware. Unlike Grin, their hardware uses standard protocols like LEVCAN and CANBUS. The display, has levels that you can set brightness on, (the cycle analyst was blinding at night) and even an autodim, that is configurable. And greatly appreciated, since I ride in the winter here in Canada, there is a automatic defroster, on the display. The controller, and onboard computer/display, cost about half of what I spent on the Grin junk.

This is not an ad for them, I really do hope they are able to keep going, but even if they are not, the genie is out of the bottle, and it's clear that it's possible to to get enough performance out of 48V, and a 1000/1500 Watt hub motor now. China will probably have a clone out soon. Or Grin, probably at 4 times the price.

Big thanks to Golden Motors, as they made building my eBike possible, and accessible. After 5+ years, and many thousands of Km, of hard, brutal use, in temps from -20 to +30, the Magic Pie 5 is the last remaining piece of my first ebike. And I don't intend on replacing it.  There has been so much growth in the tech in 5 years, I hope it continues. As it is, for the first time since I built my bike, I'm satisfied with it's performance.