Author Topic: My simple, low cost Magic Pie generator setup  (Read 8421 times)

Offline RooGM

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My simple, low cost Magic Pie generator setup
« on: March 23, 2016, 12:04:10 AM »
Here are some pics of my simple generator setup for those interested.  The Magic Pie connects to the Solar charge controller which connects to a 12V battery bank which connects to a 300 watt 12v to 110v inverter.  The inverter has 2 AC outlets and 2 USB ports.

Cost:
Solar Charge Controller: $36 CAD
12 7AH SLA batteries: $11.95 CAD each
Inverter: $27 CAD
Stand: Free (made from scraps I had in my basement)
Total cost to convert Magic Pie to a pedal generator: $86.90 CAD plus a couple of dollars tax on the batteries but the other items were tax free / tax inclusive

To convert back to a rideable electric bike is just a matter of unplugging one cable connector and plugging the battery back in.  The battery is inside the black and blue frame bag.  No settings need to be changed in the software, it always remains setup for 48V.  But when connected to the charge controller the Magic Pie puts out 12-14v at 2 to 15 amps depending on the pedalling intensity.

I also connect this setup to my solar panel when there's sufficient sunlight.  In the evening I do a pedal workout for 30 minutes and the output at any moment is between 60 and 250 watts, depending on how hard I am working out.  Over the course of the workout I guess I put an average of about 100 watt hours into the battery bank.  Between the solar and the pedal generator I am able to power all the portable devices in our home, including all phones, power banks, laptops, flashlights, battery powered lamps and in the evening our living room table lamp runs from the battery bank.  In a few days I will buy a much larger deep cycle battery because at the moment I am generating much more energy than I can use or store.  So something like a 50 amp hour battery would allow me to store more of the energy generated and run more devices.  It will also let me charge my e-bike entirely by clean energy. 

Offline Rotomnedlog

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Re: My simple, low cost Magic Pie generator setup
« Reply #1 on: June 26, 2018, 10:44:31 AM »
This is awesome! I want to replicate the set up.
So the solar charger has a 3 pairs of "+" and "-" ports: 1 solar panel, 2 battery, 3 "light bulb".

1. Shouldn't there be 3 wires coming out of the motor (3-phase AC)  ? But the solar charger has only 2 inputs "+" and "-" ?
How does this work ? (What exactly Magic Pie this is ?)

2. I see in the photos that there is something connected to the solar charger ports labeled with "light bulb". What it is?

3. Is it possible to measure the energy/electricity generated each session?

4. Why not charge the battery in the frame-bag on the bicycle?

Thank you very much. Best Regards.

Offline e-lmer

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Re: My simple, low cost Magic Pie generator setup
« Reply #2 on: June 29, 2018, 10:36:25 PM »
Quote
1. Shouldn't there be 3 wires coming out of the motor (3-phase AC)  ? But the solar charger has only 2 inputs "+" and "-" ?
How does this work ?
The three wires are three phase Alternating Current (AC).
You will need to have a three phase rectifier to convert the AC into DC.

This may be overkill, but it looks good:
https://www.newegg.com/Product/Product.aspx?Item=9SIA6RP6MN3617&ignorebbr=1&nm_mc=KNC-GoogleMKP-PC&cm_mmc=KNC-GoogleMKP-PC-_-pla-_-Tools+-+Electrician+Tools-_-9SIA6RP6MN3617&gclid=EAIaIQobChMIprWtyvb52wIVDodpCh2gUAJ_EAkYBSABEgJbpfD_BwE&gclsrc=aw.ds

You are still going to have a high and variable voltage, so you may need to get a voltage regulator to cut the power to your battery charging voltage.

Offline Andyl33

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Re: My simple, low cost Magic Pie generator setup
« Reply #3 on: June 30, 2018, 02:28:08 AM »
The three wires are three phase Alternating Current (AC).
You will need to have a three phase rectifier to convert the AC into DC.
You are still going to have a high and variable voltage, so you may need to get a voltage regulator to cut the power to your battery charging voltage.

Yes, that rectifier is way overkill but could be useful if you want to use the MP as the generator for a largish wind turbine or microhydro application.
6 Schottky blocking diodes used for solar panels should more than enough to cope with measly human power!
As for overcharging, I don't think there's much chance of the human getting accidentally "left on" overnight... however, I would definitely recommend an mppt controller to match the voltage of the motor to the battery.
If the motor doesn't spin fast enough to even reach the battery voltage, then nothing is going to get charged so a boost converter will be needed, and if more than the battery voltage, then either the battery will clamp the output voltage and it can be monitored, or use a buck converter to prevent any chance of overcharging.
There are loads of DC-DC converters on ebay and aliexpress to choose from - but really have to know the expected input and output voltage range desired.

Offline Rotomnedlog

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Re: My simple, low cost Magic Pie generator setup
« Reply #4 on: July 16, 2018, 08:44:27 PM »
Well, thank you for your replies, much appreciated.  But it didn't answer my questions.
The orginal post doesn't mention rectifier in the list of parts used nor it is visible in the photos.
How would you explain the set up then ?
Unfortunately the user hasn't show up in a year.
This topic branched out from this one where there is a bit more of discussion:
https://goldenmotor.com/SMF/index.php?topic=5864.0

Offline Bikemad

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Re: My simple, low cost Magic Pie generator setup
« Reply #5 on: July 16, 2018, 10:48:50 PM »
Well, thank you for your replies, much appreciated.  But it didn't answer my questions.

Hopefully this will:

This is awesome! I want to replicate the set up.
So the solar charger has a 3 pairs of "+" and "-" ports: 1 solar panel, 2 battery, 3 "light bulb".

1. Shouldn't there be 3 wires coming out of the motor (3-phase AC)  ? But the solar charger has only 2 inputs "+" and "-" ?
How does this work ? (What exactly Magic Pie this is ?)

The three phase wires coming from the motor go directly into the internal controller and the generated output (presumably by pedalling while regenerative braking is engaged) is delivered via the controller's Red and Black battery cables to the solar panel input of the solar charge controller.

I'm pretty sure that the motor used was a Magic Pie 4.


2. I see in the photos that there is something connected to the solar charger ports labeled with "light bulb". What it is?

It appears to be a Deans "T" type connector, presumably to allow the output to be connected to 12V lamps etc.

3. Is it possible to measure the energy/electricity generated each session?

Wiring a wattmeter into the battery supply would enable the generated power/current to be monitored

4. Why not charge the battery in the frame-bag on the bicycle?

The battery in the frame bag is 48V, which would require a much faster motor rpm to produce a decent charging voltage, and the 48V battery would be much too high for the 12V inverter he was using.


The original post doesn't mention rectifier in the list of parts used nor it is visible in the photos.
How would you explain the set up then ?

The original setup used the motor's controller instead of a dedicated rectifier, and therefore only required the battery lead to be unplugged from the bike's battery and connected to the solar charge controller's solar panel input instead.

Removing the bike's controller and replacing it with a dedicated 3 phase rectifier should provide more efficient power generation, but it would not then be possible to quickly change the function from propulsion motor to generator.

Alan