Bicycle Generator Help

[dabedwe]

I am putting together a bicycle generator and I am wondering if it is
possible to store energy produced to without batteries. i have seen
the shake/crank flashlights and lanterns that will run for 15-20
minutes after a charge. It seem that some of these have batteries,
but others do not. I have a bike, a car alternator, and a voltage
regulator for solar panels. Do I have to use batteries, or can I use
something else (such as a compactor) to hold power. I am just trying
to get some LED lights to run after 1-5 minutes of pedal power for 20+
minutes. If anyone can offer advise or send me a link where I can
find info I would appreciate it.

 

[Jeff Liebermann]

On Wed, 26 Aug 2009 18:26:28 -0700 (PDT), dabedwe
<dabedwe@hotmail.com> wrote:

I am putting together a bicycle generator and I am wondering if it is
possible to store energy produced to without batteries. i have seen
the shake/crank flashlights and lanterns that will run for 15-20
minutes after a charge. It seem that some of these have batteries,
but others do not. I have a bike, a car alternator, and a voltage
regulator for solar panels. Do I have to use batteries, or can I use
something else (such as a compactor) to hold power. I am just trying
to get some LED lights to run after 1-5 minutes of pedal power for 20+
minutes. If anyone can offer advise or send me a link where I can
find info I would appreciate it.

I think you mean capacitor, not compactor. I personally prefer
cazapitor, which describes what happens when you short the terminals.

Attach a clutch and flywheel to the drive shaft on the generator. When
the bicycle wheel is driving the idler wheel faster than the
generator, the clutch is engaged and it drives the generator. When
the bicycle wheel speed is slower than that of the flywheel, the
clutch disengages and the flywheel continues to drive the generator.
However, this is really crude and not very elegant.

Obviously, some calculations and measurements will need to be made to
see if this will work. "Some LED's" is not a very good basis for
calculations. A car alternator is far too big for this application.
Look around for a small permanent magnet motor.

You can do as well using an energy storage super-cap instead of the
flywheel. The mechanism is the same, except instead of a clutch and
flywheel, you have the supercapacitor to store the energy.
"Ultracapacitor powers bicycle light"
<http://www.edn.com/article/CA47211.html>
<http://www.edn.com/articles/pdfs/EDN/20000928/20di51.pdf>

Now, if you're really devious, you can use discard the clutch and use
regenerative braking to charge the capacitor only when you apply the
brakes. No added friction when pedaling and perhaps easier stopping.
I built something like this in 1974 by replacing the rear brake pads
with rollers that spun two small hobby motors. It rapidly destroyed
the rubber idler wheels, but basically worked. A hub-motor would have
been easier. I also have some better ideas on how to do this today,
but wanna keep those secret.

Good luck.

 

[Gnack Nol]

On Wed, 26 Aug 2009 18:26:28 -0700, dabedwe wrote:

I am putting together a bicycle generator and I am wondering if it is
possible to store energy produced to without batteries. i have seen the
shake/crank flashlights and lanterns that will run for 15-20 minutes
after a charge. It seem that some of these have batteries, but others
do not. I have a bike, a car alternator, and a voltage regulator for
solar panels.
Do I have to use batteries, or can I use something else (such as a
compactor) to hold power. I am just trying to get some LED lights to
run after 1-5 minutes of pedal power for 20+ minutes. If anyone can
offer advise or send me a link where I can find info I would appreciate
it.

OK here is the thing that all of those seemilgly batteryless devices use.
It is called a super capacitor currently typically .25 to 1 farad 5v.
These are the settings backup battery in your VCR and many audio devices.


Currently there are higher voltage versions out there. Here is a source of
information on them.

http://www.supercapacitors.org/index.htm

If you want to experiment there are many surplus sources of the small ones
for less than $2 each. But remember that stacking them does reduce
capacity. It will take some experimenting to determine how many it will
take for your time requirements. One thing to remember if using these is
that you will find a compleatly discharged bank of capacitors act as a
near short circuit when beginning to charge so a current limiting resistor
will be needed to protect your generator.

I believe that your best solution would be to NIMH batteries instead they
are less of a problem to assemble with a better discharge time life in
your application.

Gnack

 

[Jeff Liebermann]

On Wed, 26 Aug 2009 20:04:49 -0700 (PDT), dabedwe
<dabedwe@hotmail.com> wrote:

Yes I meant capacitor.

I still prefer cazapitor.

I was planning on building a light board. The
amount of LED lights I use would be determined on how much power I can
generate and store. How can I determine how big of capacitor I will
need to run X number of watts for an X number of minutes?

I'll assume that you have a constant current switching regulator (DC
to DC) between the power source and your LED's to keep them from
changing intensity as the power supply voltage goes up and down. The
basic formulas are at:
<http://www.engineeringtoolbox.com/capacitors-energy-power-d_1389.html>

I
understand that the size of the alternator would play a big role in
how fast the capacitor charges.

Please give up on the idea of using an alternator. What you want is a
small permanent magnet motor (or generator). Your bicycle idea does
not have enough power available to run the field winding of a typical
alternator.

In theory (please understand I do not
really know what I am talking about due to limited knowledge of
electronic, but I am learning) I would imagine that if I use a large
capacitor I could store enough power to run the lights for a longer
period of time. However, I am not sure how much pedaling would be
required to fully charge whatever size of capacitor I would use.

Welcome to bicycle science, and back of the envelope guesswork.
(Incidentally, your questions would be more appropriate for
sci.electonics.design).

There are plenty of articles online on using a bicycle as a generator
to charge a battery, run a TV, or do something useful with the
electricity generated. That should give you a clue as to how much
energy can be generated. For example, this contraption claims 300
watts. Yeah, sure:
<http://www.econvergence.net/electro.htm>
<http://www.los-gatos.ca.us/davidbu/pedgen.html>
"The typical adult will create 100 to over 320 watts of power
depending on the rider's strength. The average person can create
between 125 to 215 watts. Those in better shape that are stronger can
create between 225 and 320 watts or more."
The problem with this is that you're using all your energy to power
the generator, leaving nothing to move the bicycles down the road, up
hills, and in the generally forward direction. My guess(tm) is that
you would not want more than about 10% of the energy generated to go
to charging the generator. That's about 20 watts. That's also
optimistic, because unlike the stationary generator, your mobile
generator is running at wildly variable speeds. My guess(tm) is that
cuts your generated electricity budget down to 10 watts. The actual
power delivered is totally dependent on your selection of PM motor.

Assuming 10 watts stored in a 3V, with a 1 Farad super-cazapitor, you
would get 4.5 joules of stored energy. Dump that into a typical 3
watt ultra-bright white LED, and you'll get about 1 second of light.
This also assumes a DC to DC converter between the cazapitor and the
LED. I'm going to be evil (and lazy) and have you work out the number
from the above URL as a math exercise. Hint: Joules = Watts/sec
Also: The energy stored in a cazapitor is proportional to the square
of the voltage. However, finding super-caps over about 5VDC is
difficult and expensive.

Everything else scales. If you want 2 seconds, double the size of the
cazapitor. If you want 3 seconds, get a 1 watt LED.

This might give you some ideas:
"Permanent magnet generator for bicycle light operation"
<http://www.google.com/patents/about?id=MMURAAAAEBAJ&dq=6703716>
Also, follow some of the "citations" on this page for other bicycle
lights and generators.

Good luck. Sounds like a fun project. You'll probably blow up a few
LED's, buy the wrong generator, smoke the regulator, and possibly get
irate at the effort involved in driving the generator. It's all part
of Learn by Destroying(tm).

 

[dabedwe]

On Aug 26, 9:25 pm, Jeff Liebermann <je...@cruzio.com> wrote:

On Wed, 26 Aug 2009 18:26:28 -0700 (PDT), dabedwe

dabe...@hotmail.com> wrote:
I am putting together a bicycle generator and I am wondering if it is
possible to store energy produced to without batteries.  i have seen
the shake/crank flashlights and lanterns that will run for 15-20
minutes after a charge.  It seem that some of these have batteries,
but others do not.  I have a bike, a car alternator, and a voltage
regulator for solar panels.  Do I have to use batteries, or can I use
something else (such as a compactor) to hold power.  I am just trying
to get some LED lights to run after 1-5 minutes of pedal power for 20+
minutes.  If anyone can offer advise or send me a link where I can
find info I would appreciate it.

I think you mean capacitor, not compactor.  I personally prefer
cazapitor, which describes what happens when you short the terminals.

Attach a clutch and flywheel to the drive shaft on the generator. When
the bicycle wheel is driving the idler wheel faster than the
generator, the clutch is engaged and it drives the generator.  When
the bicycle wheel speed is slower than that of the flywheel, the
clutch disengages and the flywheel continues to drive the generator.
However, this is really crude and not very elegant.

Obviously, some calculations and measurements will need to be made to
see if this will work.  "Some LED's" is not a very good basis for
calculations.  A car alternator is far too big for this application.
Look around for a small permanent magnet motor.

You can do as well using an energy storage super-cap instead of the
flywheel.  The mechanism is the same, except instead of a clutch and
flywheel, you have the supercapacitor to store the energy.
"Ultracapacitor powers bicycle light"
http://www.edn.com/article/CA47211.html
http://www.edn.com/articles/pdfs/EDN/20000928/20di51.pdf

Now, if you're really devious, you can use discard the clutch and use
regenerative braking to charge the capacitor only when you apply the
brakes.  No added friction when pedaling and perhaps easier stopping.
I built something like this in 1974 by replacing the rear brake pads
with rollers that spun two small hobby motors.  It rapidly destroyed
the rubber idler wheels, but basically worked.  A hub-motor would have
been easier.  I also have some better ideas on how to do this today,
but wanna keep those secret.

Good luck.

Yes I meant capacitor. I was planning on building a light board. The
amount of LED lights I use would be determined on how much power I can
generate and store. How can I determine how big of capacitor I will
need to run X number of watts for an X number of minutes? I
understand that the size of the alternator would play a big role in
how fast the capacitor charges. In theory (please understand I do not
really know what I am talking about due to limited knowledge of
electronic, but I am learning) I would imagine that if I use a large
capacitor I could store enough power to run the lights for a longer
period of time. However, I am not sure how much pedaling would be
required to fully charge whatever size of capacitor I would use.

 

[dabedwe]

On Aug 26, 9:25 pm, Jeff Liebermann <je...@cruzio.com> wrote:

On Wed, 26 Aug 2009 18:26:28 -0700 (PDT), dabedwe

dabe...@hotmail.com> wrote:
I am putting together a bicycle generator and I am wondering if it is
possible to store energy produced to without batteries.  i have seen
the shake/crank flashlights and lanterns that will run for 15-20
minutes after a charge.  It seem that some of these have batteries,
but others do not.  I have a bike, a car alternator, and a voltage
regulator for solar panels.  Do I have to use batteries, or can I use
something else (such as a compactor) to hold power.  I am just trying
to get some LED lights to run after 1-5 minutes of pedal power for 20+
minutes.  If anyone can offer advise or send me a link where I can
find info I would appreciate it.

I think you mean capacitor, not compactor.  I personally prefer
cazapitor, which describes what happens when you short the terminals.

Attach a clutch and flywheel to the drive shaft on the generator. When
the bicycle wheel is driving the idler wheel faster than the
generator, the clutch is engaged and it drives the generator.  When
the bicycle wheel speed is slower than that of the flywheel, the
clutch disengages and the flywheel continues to drive the generator.
However, this is really crude and not very elegant.

Obviously, some calculations and measurements will need to be made to
see if this will work.  "Some LED's" is not a very good basis for
calculations.  A car alternator is far too big for this application.
Look around for a small permanent magnet motor.

You can do as well using an energy storage super-cap instead of the
flywheel.  The mechanism is the same, except instead of a clutch and
flywheel, you have the supercapacitor to store the energy.
"Ultracapacitor powers bicycle light"
http://www.edn.com/article/CA47211.html
http://www.edn.com/articles/pdfs/EDN/20000928/20di51.pdf

Now, if you're really devious, you can use discard the clutch and use
regenerative braking to charge the capacitor only when you apply the
brakes.  No added friction when pedaling and perhaps easier stopping.
I built something like this in 1974 by replacing the rear brake pads
with rollers that spun two small hobby motors.  It rapidly destroyed
the rubber idler wheels, but basically worked.  A hub-motor would have
been easier.  I also have some better ideas on how to do this today,
but wanna keep those secret.

Good luck.

Yes I meant capacitor. I was planning on building a light board. The
amount of LED lights I use would be determined on how much power I can
generate and store. How can I determine how big of capacitor I will
need to run X number of watts for an X number of minutes? I
understand that the size of the alternator would play a big role in
how fast the capacitor charges. In theory (please understand I do not
really know what I am talking about due to limited knowledge of
electronic, but I am learning) I would imagine that if I use a large
capacitor I could store enough power to run the lights for a longer
period of time. However, I am not sure how much pedaling would be
required to fully charge whatever size of capacitor I would use.

 

[Bob Larter]

dabedwe wrote:

I am putting together a bicycle generator and I am wondering if it is
possible to store energy produced to without batteries. i have seen
the shake/crank flashlights and lanterns that will run for 15-20
minutes after a charge. It seem that some of these have batteries,
but others do not. I have a bike, a car alternator, and a voltage
regulator for solar panels. Do I have to use batteries, or can I use
something else (such as a compactor) to hold power. I am just trying
to get some LED lights to run after 1-5 minutes of pedal power for 20+
minutes. If anyone can offer advise or send me a link where I can
find info I would appreciate it.

A super-cap is probably what you're looking for.

--
W
. | ,. w , "Some people are alive only because
\|/ \|/ it is illegal to kill them." Perna condita delenda est
---^----^---------------------------------------------------------------

 

[David Nebenzahl]

On 9/2/2009 8:24 PM dabedwe spake thus:

I am not planning on riding the bike on the road. It will be
stationary and used just to generate power to run lights. Thanks for
the info. I actually started this project because I have a cabin w/o
electricity. We stay there only 10-15 throughout the year. I am
hoping to provide light for short periods of time to read or to just
see. Since we are not at the cabin all the time, I am worried that
batteries would go bad. I was thinking that a capacitor would have a
longer shelf life than batteries. I am hoping that a bike generator
could supply a decent amount of light for my needs, especially since
gas prices are going up.

I guess it all depends on how much exercise you want or need to get
pedaling that generator ...


--
Found--the gene that causes belief in genetic determinism

 

[dabedwe]

On Aug 27, 1:25 am, Bob Larter <bobbylar...@gmail.com> wrote:

dabedwe wrote:
I am putting together a bicycle generator and I am wondering if it is
possible to store energy produced to without batteries.  i have seen
the shake/crank flashlights and lanterns that will run for 15-20
minutes after a charge.  It seem that some of these have batteries,
but others do not.  I have a bike, a car alternator, and a voltage
regulator for solar panels.  Do I have to use batteries, or can I use
something else (such as a compactor) to hold power.  I am just trying
to get some LED lights to run after 1-5 minutes of pedal power for 20+
minutes.  If anyone can offer advise or send me a link where I can
find info I would appreciate it.

A super-cap is probably what you're looking for.

--
    W
  . | ,. w ,   "Some people are alive only because
   \|/  \|/     it is illegal to kill them."    Perna condita delenda est
---^----^---------------------------------------------------------------

I am not planning on riding the bike on the road. It will be
stationary and used just to generate power to run lights. Thanks for
the info. I actually started this project because I have a cabin w/o
electricity. We stay there only 10-15 throughout the year. I am
hoping to provide light for short periods of time to read or to just
see. Since we are not at the cabin all the time, I am worried that
batteries would go bad. I was thinking that a capacitor would have a
longer shelf life than batteries. I am hoping that a bike generator
could supply a decent amount of light for my needs, especially since
gas prices are going up.

 

[spamme0]

dabedwe wrote:

On Aug 27, 1:25 am, Bob Larter <bobbylar...@gmail.com> wrote:
dabedwe wrote:
I am putting together a bicycle generator and I am wondering if it is
possible to store energy produced to without batteries. i have seen
the shake/crank flashlights and lanterns that will run for 15-20
minutes after a charge. It seem that some of these have batteries,
but others do not. I have a bike, a car alternator, and a voltage
regulator for solar panels. Do I have to use batteries, or can I use
something else (such as a compactor) to hold power. I am just trying
to get some LED lights to run after 1-5 minutes of pedal power for 20+
minutes. If anyone can offer advise or send me a link where I can
find info I would appreciate it.
A super-cap is probably what you're looking for.

--
W
. | ,. w , "Some people are alive only because
\|/ \|/ it is illegal to kill them." Perna condita delenda est
---^----^---------------------------------------------------------------

I am not planning on riding the bike on the road. It will be
stationary and used just to generate power to run lights. Thanks for
the info. I actually started this project because I have a cabin w/o
electricity. We stay there only 10-15 throughout the year. I am
hoping to provide light for short periods of time to read or to just
see. Since we are not at the cabin all the time, I am worried that
batteries would go bad. I was thinking that a capacitor would have a
longer shelf life than batteries. I am hoping that a bike generator
could supply a decent amount of light for my needs, especially since
gas prices are going up.

If you just want to learn electronics, invest in test equipment
and mess around building several
systems that don't work before you figure it out...go for it.

If your objective is light, give it up.
You don't say how much light you want for 15 minutes or how many 15
minutes's you want per trip. That info is critical.
But, I bet, if you do the math, you'll find that a small number of
batteries will do what you need.
You can charge 'em with the bicycle generator if you want.
Probably easier to take 'em home to make sure they're good when
you next need 'em.
Small solar panel like used to keep the battery in your RV from going
flat from disuse is also an option.

Trying to use capacitors will dramatically increase your need for
electronic knowledge...and the cost of the system.

The answer to your question is....
E = 1/2 C*v^2. Stored energy is related linearly to the capacitance.
and the square of the voltage. The available BIG caps are VERY low
voltage.
You can stack
a bunch of them in series, balance the voltages on charge and discharge,
use high voltage techniques to convert to led-acceptable voltage
over a WIDE range of input voltages.
Or you can parallel them and try to get high-efficiency switching from
low voltages.
Stored energy is the same, but you have different kinds of difficulty
using it.
Yes, you can buy assembled caps with higher voltages, but you
don't want to know how much they cost.

Bottom line is that it's tricky and expensive if you know what you're
doing. If you don't.....

 

[JB]

I am not planning on riding the bike on the road. It will be
stationary and used just to generate power to run lights. Thanks for

the info. I actually started this project because I have a cabin w/o
electricity. We stay there only 10-15 throughout the year. I am
hoping to provide light for short periods of time to read or to just
see. Since we are not at the cabin all the time, I am worried that
batteries would go bad. I was thinking that a capacitor would have a
longer shelf life than batteries. I am hoping that a bike generator
could supply a decent amount of light for my needs, especially since

gas prices are going up.

My advise would be to get a second dual-purpose battery for the car.
Drive up and pull out a line to hook-up to the spare battery and
charge up as needed. If you are using LED's you might not have
to.

 

[Gnack Nol]

text deleated:

Why not use NIMH batteries or get some solar lights and gut them for the
control circuit, batteries, and leds then recharge the batteries with the
generator hooked up instead of the solar cells.

The only thing I can think of here is that you would need to limit the
generator's voltage and current to keep from damaging the control
circuits.

Unless you are wanting very bright lights these should give ample light to
see by.

Gnack

 

[Engineer]

On Aug 26, 9:26 pm, dabedwe <dabe...@hotmail.com> wrote:

I am putting together a bicycle generator and I am wondering if it is
possible to store energy produced to without batteries.  i have seen
the shake/crank flashlights and lanterns that will run for 15-20
minutes after a charge.  It seem that some of these have batteries,
but others do not.  I have a bike, a car alternator, and a voltage
regulator for solar panels.  Do I have to use batteries, or can I use
something else (such as a compactor) to hold power.  I am just trying
to get some LED lights to run after 1-5 minutes of pedal power for 20+
minutes.  If anyone can offer advise or send me a link where I can
find info I would appreciate it.

You could try pumped storage! Large tank in the attic, pedal to pump
up the water then let it run back through a turbine/generator to run
your LED's.
Am I joking? Sort of...
Cheers,
Roger