# FAQ

QUESTION:  Can you add two generators together to run off a bicycle ?  ANSER:  Absolutely,  you can add two generators.   Note:  Spinning the PPG-R300 or PPG-B300  generator in the clockwise (C.W)  direction  will give you a positive DC Voltage.   (This is from the point of view of the generator shaft pointing at your face.)  In this direction the red wire is referred to as the “Positive” wire and the black wire is the “Negative”  wire.  It’s always good to get a cheap Volt meter to confirm your Voltage polarity.      When the generator spins in the counter clockwise (C.C. W.) direction  the black wire of the generator now becomes the positive “+”  wire and the red wire  becomes the negative “-”  .   If you choose to operate in this condition then use tape to label your wires  clearly  so there are no wiring mistakes as you get further into your project.

You have two options when you combine two generators together.   (OPTION 1 –  SERIES MODE – SAME DIRECTION)  Connect the two generators in end to end A.K.A.  “series” .    You may have dones this already have at one point in your life you put two batteries into a large flashlight end to end.   The positive of one battery was touching the negative of another battery.   Remember that 🙂   ??     This series configuration  gives you twice the Voltage as normal.  In this configuration with both gen1  and gen2 spinning in the same direction you would connect the red wire from gen2   with the black wire of gen1.  The red wire from gen1  becomes the positive for the system,  and the black wire from gen2  becomes the negative output for the system.

(OPTION 1 – SERIES MODE –  OPPOSING DIRECTION)    If the two generators  are spinning in opposing directions where gen1  spins  C.W. and gen2 spins C.C.W.  then   you would connect the black wire from gen1 with the black wire from gen2.

(OPTION 2 –  PARALLEL MODE – SAME DIRECTION)

Putting two DC generators in this configuration  gives you more current carrying capacity  by a factor  of  2x.      The two red (positive) wires from gen1 and gen2  would be connected  and the two black wires from Gen1 and ge2 would be connected.

(OPTION 2 – PARALLEL MODE – OPPOSING DIRECTIONS)  In this  scenario of having two generators spinning in opposing directions the wiring connections to be made would be to connect the red wire from the C.W. spinning generator  with the black wire of the C.C.W.    and the black wire from the C.W.  generator with the red wire of the C.C.W.  generator.

Please don’t hesitate to contact me if you have any more questions,  best wishes,   Bradley Whaley  Electrical Engineer  – Pedal Power Generator

QESTION:  Is the bike generator compatible with the Bluetti AC200P portable power station?

ANSWER:   When determining if a DC power source is compatible with a portable power station like the Bluetti AC200P  one must answer two questions:   (A)  Does the DC power source  have a max rated Voltage  that falls within the DC  input range of the Bluetti AC200P?  (N) Does the DC power source have a max current output that falls within the input range Bluetti AC200P?

BLUETTI QUESTION (A)  ANSWER:   The PPG-R500  dual generator system has an absolute  max Voltage output of  about 35VDC  with the two generators in parallel mode.  That value is measured when there is no load applied to the output of the bicycle generator system  (meaning  there is nothing connected).   In series mode the PPG-R500  has an absolute max Voltage output of about 70VDC.   The good news is that the Bluetti AC200P  has a max Voltage input of 150DC .   So the answer to this question is yes.

BLUETTI QUESTION B ANSWER:    The Bluetti AC200P has a smart MPPT charge controller that only takes what it needs in the way of charge current.  So there is no risk of the bike generator system delivering too much DC current.

BLUETTI SUMMARY:  Bases on the two questions above – the PPG-R500 dual DC permanent magnet generator system is indeed compatible with the Bluetti AC200p,     Please don’t hesitate contacting me if you have any more questions,   best regards,  Bradley Whaley  –   Senior electrical engineer,   Pedal Power Generator

QUESTION: Will a using a bigger generator or adding multiple small generators together or making a generator go much faster translate to more power output?

ANSWER: Only up to a certain point. The fact is that the human body is limited by the laws of physics to only so much power output. I have countless people bring up the idea that a really big generator could put out much more power than a small generator. Consider that a person consumes about 2,000 calories a day. This equates to about 8 million energy units called “JOULES” . A Watt is defined as a Joule per Second. So if you burn 500 food calories on a human power generator for 1 hour that equates to about 2 million Joules in one our. To convert Joules per hour to Joules per second we divide 2 million by 3600 which is about 555 Watts of power.

The disappointiong thing is that when your body burns this 555 Watts during the hour up to 75% of this power gets lost in conversion from one state to another. So it first starts as fuel that your muscles burn, The muscles then use this energy to push on the pedals of the bike, The pedals then transfer their energy to the cranks of the sprocket. The sprocket then transfers its energy to the chain, the chain then transfers its energy to the wheel, the wheel then transfers its energy to the rubber roller of the generator (Which has losses to due friction), Then the rubber roller transfers it’s energy to the shaft and rotor of the generator, the rotor then transfers its energy to push electric winding coils through a strong magnetic field created by permanent magnets, the winding coils capture flux from the magnet fields and drive current through the windings, the current flows into your battery or light bulb.

In every one of the state changes mentioned above, some energy is lost. So if your body is putting out 555 Watts during that one hour then the actual amount of electrical energy it is generating is around 145 Watts of power. It doesn’t matter how big the generator is or how fast it is, you will always have the limitation of the human body. The more power you try to generate with your body, the more your body feels drag and you slow down and get tired. Another way of looking at it is if I tell you to ride your bike up a hill that is too steep. You tell me no , and I say “why” and you say , because it is too hard to ride up that hill. Let me know if you have any more questions, Bradley – Electrical Engineer – http://PedalPowerGenerator.com

How do I remove the tire from my bicycle?  Watch video instructions shown   Here

What is a Watt?  A Watt can be compared to Velocity  which is a measurement of how fast you are going.     When a Watt is combined with a time value such as second, minute, hour, then it becomes a measurement of work done.    The formula for Watts is Volts x Amps.

Below is actual data collected from a bike generator during a one hour session.  The white line in the graph below shows actual Voltage of a lead acid battery being charged by the bike generator.   The red line represents the Amps  measured.

At one point in the chart the Amps reach a value of 21.  At that same point, the Voltage reaches about 14.  When we multiply 21 x 14 we get  294 Watts.   The second graph below in green is the Watts graph.

How much energy can I generate with a Pedal Power  bike generator system?

Typically an adult who exercises on a regular basis and can generate about 100 Watts of power over a one hour period.   A competitive rider can average 200 to 300 Watts during a one hour period.     To put this into perspective,  that much energy would power a cell phone for over a month.   But would run a 500 Watt blender for only a few minutes.    The calculations for energy produced are in “Watt Hours”    which is calculated by multiplying  Watts x  Hours.    The energy unit used to charge you for power being delivered to your home is “KiloWatt Hours”   Which is simply Watt Hours  divided by 1,000  .

What kind of things can I do with energy generated from my body?

You can:

• Charge a deep cycle 12V DC  battery (Using a blocking diode)
• Charge cell phones  (Using a blocking diode and Voltage regulator)
• Light a room with an LED light bulb (Using a blocking diode,  Voltage regulator,  and AC inverter).
• Charge a laptop computer  (Using a blocking diode,  Voltage regulator,  and AC inverter).
• Power a 12V  blender to make drinks or smoothies at a party
• Power a leaf blower pointed in the up direction with a pin pong ball floating  in the air.
• Power a wheat grinder to make bread (Using a blocking diode,  Voltage regulator,  and AC inverter and portable powerpack)
• Power a 50 Watt flat screen  TV  and DVD player  (Using a blocking diode,  Voltage regulator,  and AC inverter).
• Power a PA sound system  (Using a blocking diode,  Voltage regulator,  and AC inverter).

This schematic and bill of materials  in the PDF file below shows a simple solution to suppressing too much Voltage from a human power generator.  This happens when an over excited rider decides to go crazy on the generator system at a speed that is excessive.   When  using  pedal  power  bike  generator   it  is often  necessary  to  use  this   type  of   circuit  to  protect  a 12V  light  bulb   from  being blown. The 300 Watt 12 ohm power resistor in the bill of materials is adjustable and can be kept from over heating by installing a fan next to it.

•

What are the calculations regarding charging a 12V battery?

Some people like to store their energy into a potable battery powerpack.   A typical battery size for a powerpack is something near the 25 Amp Hour range.   Amp hours is different than “Watt Hours”  because the unit of measurement is in “Current”  or “Amp”  instead of “Watts”  .     Amp hours can be converted to Watt Hours if you use the Voltage rating on the battery  which is typically 12V DC.     Amps X  Volts  =  Watts  so in an ideal world   you could say that  a battery with a 25 Amp hour rating can put out 25A  x 12V  =  300 Watts   during a one hour period.

Below is a graph showing Watt hours.  The green line on the chart below shows you the output of the belt drive pedal power generator system.    The red line represents the Amps of current flowing into a battery  and is associated with right axis on the chart in red font.   The data was captured by the WattsVIEW power monitor.   In this demonstration the person riding the MNS Power generator system  started pedaling at about 3:07 PM  and stopped at around 4:30 PM.    The peak current during the time period shown was about 12.5 Amps.    You can see that the average current  during this time was about 5.5 Amps.    So if you had a 25 Amp hour battery  then the time required to fully charge it from being completely dead would be calculated by dividing  25 AH /  5.5 Amps =  4.5 hours.

Can I get more energy out of my system  by using  two generators  instead of one,   or by using  a flywheel,  or using a  bigger generator  or higher gears?

The human body is limited too how much  energy it can put out,  no matter  how you setup your generator system,  the human body can only put out an average of 100 to 150 Watts during a one hour period.     Putting a bigger generator on your system does not give you the ability to generate more energy.   It may make your system a few percentage points more efficient  like from 94% efficiency to 95% efficiency  (Where efficiency is  calculated by  power out of the system divided by power into the system.)

We were  recently  asked to analyze a a pedal power system that an inventor had claimed would allow a person to generate well over 1,000 Watts of power.   He had a fly wheel on the system and TWO generators.   Dozens of investors had dumped in hundreds of thousands of dollars into this invention.    The results of testing the system out by measuring current to the battery bank showed that this inventor had made a huge mistake in his claims.   He had made two mistakes:

1. He had assumed that because his generator was rated for 1,000 Watts output  that meant that a person could automatically put out 1,000 Watts on  a bike generator
2. He had assumed that putting two of these on a pedal power system would automatically double his output to 2,000 Watts .

The rating on a generator or PMA (Permanent magnet alternator)    simply states the max rated power output of the unit.    There is no free lunch.

Some people have tried adding a fly wheel to the system to store the energy.   This  does nothing to increase power output.  It simply stores your energy  represented by the formula  for kinetic energy stored in a rotating body which is

Note:    The inertia is calculated by taking the mass of the flywheel in kg  and multiplying it by the square of   the radius of the flywheel.  And angular velocity is  in radians per second.     But you don’t need to be a scientist to understand all this.   Just know that a fly wheel stores energy.  IT DOES NOT INCREASE IT.    So when you see the many misleading  web pages on the internet claiming that fly wheels will increase  energy output beware.

How can I build a DIY light bulb display that turns on while being powered by a bike generator system?

The diagram schematic circuit below shows the parts needed to make your own light bulb display with a bike generator, It utilizes the Arduino Uno and an 8 channel relay board.