Picture of personal powerPlant
The personal powerPlant is a portable device that harnesses electricity through a solar cell and hand crank generator, into a NiMH battery. The device also includes a visual multimeter that monitors the amount of energy stored. The personal powerPlant can be used to power applications up to 8V at 70 mA.

Designed by: Mouna Andraos, Jennifer Broutin, Carmen Trudell with Mike Dory @ Eyebeam for the Alternative Energy Workshop 06.23.07



Step 1: Materials

Picture of Materials
For the powerPlant circuit
1 - Stepper motor (Japan Servo KP4M4-029 12VDC)
1 - Solar panel (8V)
1 - NiMH battery (7.2V, 70 mA)
8 - 1N4001 Diodes
3 - Terminals
1 - 5 pin male header
18 or 20 gauge solid wire (red, black, blue, green)

For the visual multimeter
1 - Red LED, 1.5V
1 - Yellow LED, 1.5 V
1 - Green LED, 1.5 V
1 - 100 Ohm resistor
1 - 150 Ohm resistor
1 - 1N4730 (3.9V) zener diode
1 - 1N4733 (5.1V) zener diode
1 - 1N4737 (7.5V) zener diode
1 - momentary switch

1 - 2.5"x1.75" PCB prototyping board
1 - Printed Board Diagram (download pdf below)
Schematic Circuit Diagram for reference (download pdf below)

Case Template (download dwg/pdf below)
1 - 3.5"x3.5"x4.5" Acrylic Box
1 - 3/16"x1" Binding Post with screw
3 - 3/16"x1/4" Binding Post with screw
3 - #10 SAE Washer
2 - #4 machine screw bolts
Gear Template (optional, download dwg/pdf below)
1 - 4"x5"x1/8" sheet plexiglass for Gears (optional)

Soldering iron
Wire Stripper
Screwdrivers (Phillips and Flathead)
Exacto Knife and Blade

Places to find supplies:
Home Depot
Radio Shack
Container Store
Electronics Goldmine
Jameco Electronics
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Price range?
cristi.criz3 years ago
I like this instructable!

I understand that it is good to have a stepper motor with 6 pins, but a stepper motor with 4 pins isn't good?i think it is.

Some improvement: I think is better to chose a 15 V stepper, and put a capacitor (2000uF 25v) and a voltage regulator( 7.5v) to have a regulated voltage to charge the battery more better.
I just want to say that this is very well done and a good starting place to learn the basics of much bigger systems but the battery is way to small is only 1/2 a Watt/hour of total energy. mp3 players and cellphones use at least 2 Watt/hours to charge and average around 3-5 Watt/hours and have there own method of current limiting and waste energy doing so even a small pen drive mp3 player with a 3.7v 100mAh that's .37 Watt/hours is gonna use all if not more than the 1/2 W/h battery has to offer in the sun all is good but at night expect to do some cranking .

All in all Its a great learning tool by the size of the solar panel it can charge that battery in less than an hour find the mAh output of your solar panel and how much usable sunlight you get in a day and take the mAh times it by hours of sunlight and then you will have the size battery you want
lukeD4 years ago
nice drawings!

rate *5
amklose4 years ago
I found a KP4M4-029 motor lying around the house. Now I wish I had time to build this awesome project!
IL_G5 years ago
hi! this project is really interesting! I have a little question about... can be used a simple DC motor with a single coil instead of a Servo? and it must have an output of 12V?
Thank you for making this project.
Treknology IL_G4 years ago
Any motor that relies on permanent magnets should be able to produce some electricity.

Stepper motors are actually quite inefficient as motors because they are drawing current just to stand still. They are not capable of "running themselves" like regular DC motors found in toy cars and such. Their popularity in the computer world is precision placement. As used in this 'ible, they make fantastic generators/alternators.

The output from the stepper motor will be very spiky--you may get a very high voltage that bites, but lower current capacity.

The output from the toy car motor will be unregulated DC, the polarity determined by the direction of spin.
i love the printed diagram... awsome! (still reading this ´table) nice!
Foaly75 years ago
Can this be built with a few outlets for plugging in some stuff?
rpvanpatt5 years ago
 Does battery size matter?  I am trying to basically take your plan and tweek it a bit
Stetran15 years ago

I couldn't find any KP4M4-029 anywhere. As an alt motor, is it possible to use any other 12V stepper motors?
You should be able to get away fine with another 12v stepper. Make sure it is not bipolar (4 wires) though
comodore5 years ago
Hmmm. I may be wrong, but isn't 70 mA to small?
My MP4 can be charged by a USB cable going into a computer, but on the back it says 4.5V 500 mA.
Can this device power my MP4?

Thank you!
Jodex comodore5 years ago
You can charge with less current (amperes) , but it will be slower. You can't charge with less voltage than your battery's rated voltage is. So more current, faster charge, but TOO(!)  much current will destroy the battery. : D
comodore Jodex5 years ago
Thanks Jodex!
I am planing on building one so I wanted to see if I could put a USB female exit or what ever you call it and make it charge my MP4...

Jodex comodore5 years ago
Yes, USB female connector! : D Definately put one there! It will be great : D
Jodex comodore5 years ago
Oh, so the answer is Yes. : DD
awwwwwwwww Ill have to wait till friday to do mine laser cutters at school Apparently students arent allowed to borrow it
cb_designer7 years ago
so I've been looking for the KP4M4-029 motors and it seems they have been discontinued... any suggestions on an alt. step motor? or where i can by this motor?
Go to your nearest goodwill and buy an old printer. Doesn't matter if it is ink or laser, and rip it apart, there should be a motor inside that works.
cyborn956 years ago
I am having trouble finding a 8 volt 70 mA NiMh battery. Does it really have to be 70 mA or can it be more around a couple thousand?
It does not matter The higher the miliamps the longer it will take to charge You could use a car battery if you wanted to(maybe some diodes or something would be a good idea)
what changes I have to make to power devices upto 230v ,please help me.I don't know much about this project can u please send the full details of this project.
Well First you gotta make it 12-15 volts by using a 12 batt(a small lead acid will do) Next,You need a 12 inverter(I have 120V ones but i'm sure that there are 220V ones too) Simply connect the 12V output to the inverter and you got yourself truly a personal powerPlant
Wesley6667 years ago
The stepper motor you used is the exact same one I have but I also have a lemon shaped one that is half the size and produces twice the power. So my question is would I need a battery that is twice the voltage or would 7.2 v still be fine? I also built the circuit differently for my motor using only two diodes and a resistor instead of five diodes as well as My motor only needs two wires to be connected. The other three wires I found out did absolutely nothing.
I also used a transformer and that is why I only needed the two diodes and a resistor.
natrinicle7 years ago
I happen to have a bunch of old cell phones with lithium ion battery packs and am constantly looking to do something with them. Would I be able to substitute a li-ion battery pack directly in, or do I need a circuit to control the charge? If I do need a circuit, a schematic would be highly helpful as I have many old broken electronics that I could scrounge old parts off of. Thanks in advance!
jabroutin (author)  natrinicle7 years ago
lithium ion batteries are a bit more finicky in terms of circuitry. and they don't like to be charged and discharged in a less continuous flow - which is what you will be getting out of this stepper motor turned generator, so I would not suggest using them. But maybe you can come up with something - let me know how it goes.
They wont explode if I charge them without a special circuit though will they? I'm thinking about the solar cell portion directly driving the battery...
jabroutin (author)  natrinicle7 years ago
yes, it very well could explode. any battery will do that without the proper circuitry, and the circuitry will be different for each type of battery, as well as voltages for different batteries. There is no general schematic in other words.
Do you have any ideas on where I can locate some form of charging circuit for a 3.6v lithium ion battery then? Or is there someplace that will help me in isolating the circuit and cutting it out of the cell phone itself?
Never mind, found it! http://www.seattlerobotics.org/encoder/200210/lithiumion.htm for any others with the same question
use the charging circuit from the phone
shaygirl6 years ago
how much will you spend to have this invention?
awkrin7 years ago
nice, maybe I'll make one of these since I already have a stepper motor(with 6 wires for some reason)... if u get a monkey and train it to crank that thing, u can get almost free electricity .
would you feed him bananas?
Derin dombeef7 years ago
im gonna disguise into a monkey now
dombeef Derin7 years ago
Derin dombeef7 years ago
ah man
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