For this project I refined some of the lessons I've learned building (or trying to build) bike generators in the past in an attempt to build one that was quiet, less obtrusive in our living space, and capable of being used by a bicycle without any modifications or additions to the bicycle. The Table is flipped over onto its side when you need to use the generator and functions as a front wheel rest to stabilize and balance the bike. I built the pedal generator and the table cover from scrap wood and a treadmill that I found in the trash out on the street. For power storage and use I used a Deep Cycle Marine Battery and a 400 Watt Inverter I purchased from Harbor Freight. I also built a voltage regulator using some electrical components from scraps and I realize that painting it wasn't quite as green as leaving it au naturale, but I figured the paint would help prevent the wood from rotting and having to build another one. While the generator stand is made from scrap materials I found I did buy the battery and the inverter, as well as some of the components for the Voltage Regulator I couldn't find in E-Waste. I connected the generator input voltage to a Deep Cycle Marine Battery and Inverter through a diode and Voltage Regulator that I made.
I attached the Voltmeter where the Battery typically would be. I did the little backwards pedal hiccup halfway through to show why a heavy flywheel sort of thing is great to have an a pedal powered generator, it helps get the spinning smooth. The reason the Voltage stays up after I finish pedalling is the inverter holding a bit of the charge in a capacitor somewhere I guess. The beep at the end is me turning the inverter on so it drains the little bit of residual it had in its system. Normally the plastic tub with the battery and electronics is inside the house, I just moved it out so the video would be easier to shoot, the cord goes in a slot under the door usually.
Finding The treadmill a while back was definitely the impetus for this project. While they aren't something one sees everyday out in the trash, they aren't too hard to come by if you keep your eyes open(and watch craigslist too).I have built bike generators before with broken cordless drills and they are very noisy(best case scenario as loud as a drill), also the drill can't support or balance the weight of a bicycle and that required a stand of some sort to rest bicycle pegs in. I fixed both those problems in this iteration.
I hope in the future to build a charge controller to add to the system so I can add some solar panels and/or a wind turbine generator to power the battery(or in future batteries). I'm currently working an a charge controller design I found at http://mdpub.com/555Controller/
. My electrical work is pretty novice so if you notice any ways you feel the voltage regulator could run better please feel free to let me know.
Step 1: Materials and Tools Used
Scrap Wood (I used mostly 2X4's, some 1X6's, some 2X6 scraps and 1X4's, a scrap piece of plywood, and I made the legs of the table from scrap 2X6, it was based mostly on what I could find in dumpsters/outside construction sites)
EverStart 12VDC Deep Cycle Marine Battery 101 Amp Hours
Parts from Treadmill
-DC Motor (motors vary from treadmill to treadmill, this one is rated for 90V continuous duty so it will definitely be able to take the spinning of the bicycle. I hope one day to use this in some sort of wind powered generator, but for now in our small apartment scenario its the bike generator
-Freewheel that screwed onto the shaft of the motor. If the DC motor from your treadmill has one attached to the shaft that the belt sits on ( and most I've seen do) then you're in luck. The freewheel helps the wheel keep spinning if you "hiccup" while pedalling, and smooth out the spin.
-2 rollers (the rollers that came off the treadmill can support of a lot of weight, and also one is already set up to spin the rubber belt that the motor used to use to turn it.)
Paint- Get Creative with it! I painted mine with some cans leftover from other projects, so it it would look better and also be protected from the moisture and sun here in New Orleans
Parts for Voltage Converter
LM317 Adjustable Voltage Regulator
100 ohm resistor
1K ohm resistor
Processor Heat Sink and Fan taken from broken Desktop Computer Motherboard
Cordless Drill with bits
Pencil for marking Holes and Cuts
Table Saw (You can do the project with just a hand saw but I had the opportunity to use a Table Saw to Cut the Boards for the Table to go over the generator so it definitely saves some time/energy)
Step 2: Cutting the Boards for Generator Stand and Table
The First Step is to cut and paint the boards for the Generator Stand and Table. There isn't a set measurement to this, as the dimensions for the frame of the generator stand will vary depending on the parts from the particular treadmill you get your hands on. I measured the rollers and built a frame that would allow the axles to rest on the edges and be far enough apart for the bicycle tire to seat between the rollers and not jump out of them when I start pedaling. Graph Paper was definitely my friend in laying out the lengths of the boards I needed. Sorry for already having the boards painted in most of the pictures, I kind of got excited and forgot to take pictures. After Spacing the rollers, I cut a slot in a board to set the electric motor on, then added scrap pieces to use as risers in a later step when I attach the motor to the frame. I'll need the risers to put enough distance between the roller and the motor to keep the belt taut.
Step 3: Building the Generator Stand
With the pieces cut I assembled the Frame with a cordless drill and screws. After building the "Rectangular" base, I applied a coat of orange paint. I then added the rollers, and the slotted board to mount the motor on in the corner. I angled a board to provide extra support for the dc motor I'm using as a generator.
Important Note:When You attach the rollers make sure you have it threaded through the rubber belt so you won't have to do it later, you can always do it later but saves you some effort.
Step 4: Attaching the DC Motor/Generator
In the next Step I added the boards I cut as risers until I had enough space between the motor/generator and the roller for the belt to be tight. Be sure to place the motor parallel to the roller so the belt will turn turn smoothly. After lining up the pieces I screwed it together . I staggered the screws every layer of boards to increase the strength.
Step 5: Building the Table/ Front Tire Stand
I built the table to cover the generator stand with so that I can protect it from weather and also still use the square footage that it takes up on the deck. Nothing fancy, I just attached from legs I cut to the bottom of the plywood scrap I trimmed down and then went around it with some other boards so it would look better and be stronger. Next I Added 2 cut boards of 2X6 as shown with bracers between for strength I made from scrap wood. I waited to cut the boards until this step because I didn't trust my measuring/manufacturing skills to cut them earlier and have them fit properly in this step. When the Boards are added the front tire of your bike should fit snugly into the gap.
There's the Tabletop/Front Wheel Stand! Now onto the battery/inverter setup.
Step 6: Building the Voltage Regulator, Hooking Up the Electronics and Battery
The Voltage regulator I built following the schematics on the back of the packaging for the adjustable LM317 voltage regulator from radioshack. Using the Formula provided I determined the 100 ohm and 1K would produce the output voltage of 13.75 VDC, which would be suitable to charge the battery. As you can see in the Video in the Intro, the Voltage that ended up coming out was 13.33ish, due to losses to heat and the blocking diode, which is still suitable to charge the battery. There is no protection currently in place against overcharging the battery, my thought being one will be able to monitor the battery while charging, and overcharging will require quite a bit of hard pedaling and it will be apparent to the generators operator. Whenever I finish the charge controller I will add it to the system so I will also have the option to add solar or wind power to it. I uploaded a schematic below.
IMPORTANT: Be sure to attach a substantial heat sink to the LM317 component, it will get pretty hot when you are pedaling as it converts the voltage down for the battery.
That being said- Use the Heat if you can- maybe I'll try to add a stirling engine or something in the future, that'd be neat. Though as off now the heat sink is dissipating the heat really well and its not really warming up too much. I attahed the LM317 component to the PC Heatsink using thermal compound and then later a layer or epoxy over the piece to hold it on.
I mounted the Voltage Regulator, 12 V deep cycle battery, and inverter in a used Cat Litter Bucket. I picked this container as it held everything and also kept the battery off of the ground.
First I hooked the Battery to the 400W inverter I purchased from Harbor Freight.
Next was connecting the cables from the generator through the Voltage Regulator to charge the battery. be sure to add a diode to the line between the generator to the voltage regulator as shown so the voltage won't backfeed from the battery to the electric motor. The Diode does cause a small drop in Voltage, but its worth it to not have voltage backfeed through the circuit from the battery or accidentally damage the components if I I happen to hook the generator up in reverse.
Step 7: Hook the Generator to the Electronics and Battery. and Completed!
The Next Step is to Attach the Generator to the Electronics and Battery. It is good to use a larger size wire to do this so energy isn't lost to resistance in a small diameter wire. I used the cord that I salvaged from a broken vacuum cleaner that I spotted on my way into work one morning. I used my Dremel to cut the plugs down so they fit the solderless type fittings that the motor already had wired into it. Now the tricky part- You want to connect the generator so it delivers the V+ in and Ground/Negative where its supposed to, and not in reverse or else the whole thing won't work. The Key to figuring this out is to take a voltmeter and measure the voltage on your battery, making note which color probe is on the Positive and which is on the Negative, then compare that reading with what you read from the generator when you spin it by hand the direction the bike will spin it it. For example, If I used my Red Probe on the Positive of the Battery and the Black Probe on the Negative of the Battery, and red a Postive number, then when I switch the Leads to the Generator Output and read a Positive number when it is spun, whatever Lead the Red Probe is attached to is the positive lead. Using This method I wired the generator to the Battery/inverter through the Voltage Regulator.
I realized at the ending of making this instructable I needed to drain the battery down a bit so I can tell you how long it takes to recharge with pedalling. so as soon as I drain it down a bit I will charge it up and report back on the time it took.