Marco Trapanese
Guest
Sat Mar 06, 2010 11:38 am
Hello,
let's say I want to light a led (steady, not flashing) of some hundred
mW. I'd like to use a magnetic energy harvesting method, for example the
classical strong magnet into a coil (suggestion about other e.
harvesting method are welcome; no thermal or solar, though).
Given the following condition (estimated) for the magnet movements:
frequency of oscillation: 1 Hz
acceleration: 1 m/s^2
max velocity: 1 m/s
I want to estimate the dimension of the magnet and of the coil to
produce the needed energy. I bet they will quite large... but I need
just an order of magnitude.
Here another way to see the problem.
Given the coil:
length: 50 mm
internal diameter: 10 mm
# of turns: 300
wire diameter: 0,1 mm
and given the magnet:
material: neodymium
shape: cylinder
diameter: 10 mm
length: 10 mm
and given the information above about its movements, how much energy the
system could provide? I'm interested to a rough value: 10 uW, 100 uW, 1
mW, 10 mW etc...
Thanks in advance for any answer
Marco
D Yuniskis
Guest
Sat Mar 06, 2010 6:54 pm
Marco Trapanese wrote:
Quote:
Hello,
let's say I want to light a led (steady, not flashing) of some hundred
mW. I'd like to use a magnetic energy harvesting method, for example the
classical strong magnet into a coil (suggestion about other e.
harvesting method are welcome; no thermal or solar, though).
Given the following condition (estimated) for the magnet movements:
frequency of oscillation: 1 Hz
acceleration: 1 m/s^2
max velocity: 1 m/s
I want to estimate the dimension of the magnet and of the coil to
produce the needed energy. I bet they will quite large... but I need
just an order of magnitude.
Here another way to see the problem.
Given the coil:
length: 50 mm
internal diameter: 10 mm
# of turns: 300
wire diameter: 0,1 mm
and given the magnet:
material: neodymium
shape: cylinder
diameter: 10 mm
length: 10 mm
and given the information above about its movements, how much energy the
system could provide? I'm interested to a rough value: 10 uW, 100 uW, 1
mW, 10 mW etc...
google "shake light"
The problem you will have is you *still* need storage
of some sort (lest the light blink).
Marco Trapanese
Guest
Sun Mar 07, 2010 1:54 pm
Il 06/03/2010 18.54, D Yuniskis ha scritto:
Quote:
The problem you will have is you *still* need storage
of some sort (lest the light blink).
Yes, that's true. A supercap for example.
But at the end the energy provided must be enough to power the load even
with the storage unit. Otherwise the led will turn off after some time.
Marco
D Yuniskis
Guest
Sun Mar 07, 2010 7:58 pm
Marco Trapanese wrote:
Quote:
Il 06/03/2010 18.54, D Yuniskis ha scritto:
The problem you will have is you *still* need storage
of some sort (lest the light blink).
Yes, that's true. A supercap for example.
New devices use a small Li cell. And, when *that* dies
(refuses to accept charge) you throw the thing away!
Quote:
But at the end the energy provided must be enough to power the load even
with the storage unit. Otherwise the led will turn off after some time.
Marco
Marco Trapanese
Guest
Mon Mar 08, 2010 3:23 pm
Il 07/03/2010 19.58, D Yuniskis ha scritto:
Quote:
New devices use a small Li cell. And, when *that* dies
(refuses to accept charge) you throw the thing away!
So, what's the advantage of the Li cell instead of the supercap?
Quote:
But at the end the energy provided must be enough to power the load
even with the storage unit. Otherwise the led will turn off after some
time.
Any rough values for sizes of magnet and coil to obtain some hundreds
mW? Just to know how big should be the "torch".
Thanks!
Marco
D Yuniskis
Guest
Mon Mar 08, 2010 7:08 pm
Marco Trapanese wrote:
Quote:
Il 07/03/2010 19.58, D Yuniskis ha scritto:
New devices use a small Li cell. And, when *that* dies
(refuses to accept charge) you throw the thing away!
So, what's the advantage of the Li cell instead of the supercap?
Marketing! Pick up one of the Li cell shake lights, shake it
for a few seconds, turn it on: "WOW! LOOK HOW BRIGHT THAT IS!!!"
(Li cell undoubtedly still has a charge from the last person
who shook it or from the factory, etc.)
Let it sit, unused, on a shelf for a year (after all, it is just
for EMERGENCY USE, right?) and wait for The Big Disappointment
when you shake the sh*t out of it and find *nothing*! :>
The same is true of the "crankable" flashlights now en vogue.
I've debated whether replacing their Li cells with supercaps would
be a step in the right direction or just a different sort of
failure waiting down the road.
(I have a "squeeze" light that works well -- all the energy is stored
mechanically -- but it gets tiring to use)
Quote:
But at the end the energy provided must be enough to power the load
even with the storage unit. Otherwise the led will turn off after some
time.
Any rough values for sizes of magnet and coil to obtain some hundreds
mW? Just to know how big should be the "torch".
No idea. I was pointing you at the shake lights thinking you
could get an idea from them (physical size, etc.). I have seen
them in sizes similar to a "2 D-cell" flashlight and a "2 C cell"
flashlight. Both used Li cells and both had LED emitters.
(seeing one with an incandescent lamp would be more telling)
Marco Trapanese
Guest
Mon Mar 08, 2010 8:19 pm
Il 08/03/2010 19.08, D Yuniskis ha scritto:
Quote:
Marketing! Pick up one of the Li cell shake lights, shake it
for a few seconds, turn it on: "WOW! LOOK HOW BRIGHT THAT IS!!!"
(Li cell undoubtedly still has a charge from the last person
who shook it or from the factory, etc.)
Let it sit, unused, on a shelf for a year (after all, it is just
for EMERGENCY USE, right?) and wait for The Big Disappointment
when you shake the sh*t out of it and find *nothing*! :
Ok, I got it.
Quote:
No idea. I was pointing you at the shake lights thinking you
could get an idea from them (physical size, etc.).
No problem, thank you.
Marco
Dirk Bruere at NeoPax
Guest
Tue Mar 09, 2010 10:07 am
On 06/03/2010 10:38, Marco Trapanese wrote:
Quote:
Hello,
let's say I want to light a led (steady, not flashing) of some hundred
mW. I'd like to use a magnetic energy harvesting method, for example the
classical strong magnet into a coil (suggestion about other e.
harvesting method are welcome; no thermal or solar, though).
Given the following condition (estimated) for the magnet movements:
frequency of oscillation: 1 Hz
acceleration: 1 m/s^2
max velocity: 1 m/s
I want to estimate the dimension of the magnet and of the coil to
produce the needed energy. I bet they will quite large... but I need
just an order of magnitude.
Here another way to see the problem.
Given the coil:
length: 50 mm
internal diameter: 10 mm
# of turns: 300
wire diameter: 0,1 mm
and given the magnet:
material: neodymium
shape: cylinder
diameter: 10 mm
length: 10 mm
and given the information above about its movements, how much energy the
system could provide? I'm interested to a rough value: 10 uW, 100 uW, 1
mW, 10 mW etc...
Thanks in advance for any answer
Marco
100g Nd magnet dropped through 1 m height.
Max energy = mgh = 0.1 x 10(approx) x 1 = 1 Joule
Do it once a second and you get 1W
--
Dirk
http://www.transcendence.me.uk/ - Transcendence UK
http://www.theconsensus.org/ - A UK political party
http://www.blogtalkradio.com/onetribe - Occult Talk Show
