Follow and learn how a 10 year old girl builds her first serious science project, "The Bio-Battery."
See how this young lady, my daughter, astounds her 5th grade class with her project constructed from simple parts from a local electronics store, some instruction from her father, and some house hold edibles and powers a light with it all. Warning! You may become enlightened.
Submitted to the "Science Fair Contest" which is sponsored by AMAZON.COM You will see some AMAZON.COM promotions that I put in. This is part of the requirement for the contest and a thank you to Amazon for supporting it. Thanks for reading. Enjoy.
Step 1: Consumable Materials
The follow materials were used to complete this project.
(1) Plastic Project box Purchase on Amazon.com
(1) Momentary Push Switch Purchase on Amazon.com
4 Copper Pennies
4 Lemons (or other citrus)
(4) Galvanized( Zinc) Cotter pinsPurchase on Amazon.com
A length of 18 Gauge telephone wire Purchase on Amazon.com
(1) 3 volt 5mm Blue L.E.D. light (Light Emitting Diode) Purchase on Amazon.com
(1) 5mm L.E.D. light mount/holder Purchase it here (Sorry Amazon)
(2) 2 Inch x 4 inch PVC pipe coupling or PVC pipe -----(Purchase at local hardware store)
(1) Acid brush Purchase on Amazon.com
(1) Project board (plywood or even cardboard)
Small amount of Bernzomatic Rosin Core Solder Purchase on Amazon.com
Small amount of "Elmer's Blue Bull Polly Glue" Purchase on Amazon.com
See all of the pictures below.
Step 2: Required Tools
The following is a list of tool that were used to complete this project.
Safety Glasses Purchase on Amazon.com
Hot Glue gun Purchase on Amazon.com
Drill (14.4volt Ryobi) Purchase on Amazon.com
Drill bits Purchase on Amazon.com
Phillips screwdriver Purchase on Amazon.com
Spring loaded center punch Purchase on Amazon.com
Soldering gun Purchase on Amazon.com
Multi-Meter Purchase on Amazon.com
Hacksaw Purchase on Amazon.com
Wire strippers Purchase it on Amazon.com
See all of the pictures below.
Step 3: Hypothesis
Will 4 lemons have enough current (moving force) to light a L.E.D. light?
With the lemons connected together, using a metal wire attached to electrodes on each side of the lemons, an average of about 3 volts should be registered on a multi-meter. This is enough power that the light to come on.
Step 4: Abstract- What Is a Bio-Battery and How Does It Work?
A Bio-Battery battery consists of two different metals suspended in an acidic solution.
All batteries have 2 sides, Positive "+" and Negative "-" sides which are called terminals. Electrons flow, like water in a river, from the "-" electrode terminal, let's call it the top of a waterfall, of a battery, through a conductor, towards the "+" electrode terminal, let's call this the bottom of the waterfall, of a battery.
When electrons flow from the top of the waterfall to the bottom it is called current. It is very similar to the movement of a real river current but is so small you can't see it.
The movement of the waterfall has a moving force that pushes, this movement is called current. When this moving force (current) is measured, it is measured it what is called voltage or volts.
This moving force is going to make the LED light up.
Please remember even though this is a very low voltage High voltage can Burn or Kill!
Step 5: Items to Remember
**Remember** The red wire connected to the first lemon (at the penny) is the "+" positive side. On the opposite side of the lemon is the cotter-pin which is the "-" negative side.
Electrons actually flow from the "-" (cotter pin) end of our lemon battery through the LED (making it glow) then back to the "+" (penny) end of the battery. This is an electronic circuit. The LED glows intensity varies with the amount of lemons used in this configuration.
Step 6: Preparing the Project Box.
Caution always wear eye protection.
1. (See picture 1. and 2.) Holly starts off by setting a drill hole for the LED holder and the momentary switch into the project metal box cover using a center punch. Note** Don't do this on your dinner table some family members may get upset.
2. Determine the size of the drill bit that you will need by comparing the size of the LED holder threads and the momentary switch threads. To big and you could have a problem securing your items. To small is ok because you can always use a small file or drill bit to round our the holes to the proper size.
3. (See picture 3. and 4.) Holly begins to drill the hole for the LED mount and momentary switch. **"Info Note** Again, Don't do this on your table( we moved to the patio table) some family members may get upset. (You think we would have learned the first time.)
See all the pictures below
Step 7: Installing the Switch and Holder and LED.
1. Now that the holes are drilled Holly installs the LED into the holder. The LED holder has two little holes one for each of the wires of the LED to route through.
Once in position the light will not move because the inside of the holder has a rubber type of grommet that keeps the wires from moving, it is a snug fit.
**Info Note** Not all LED's have wires attached much less plastic connectors. If yours has the connectors, cut them off and strip the wire to install the LED into the holder (that is if you are using the same setup as Holly has). Holly's LED did not have wires connected, but we will get to that in the next step.
2. At this point Holly installs the switch and holder in to the panel of the project box and tightens the nuts down on each one, this secures it to the box.
See all of the pictures below.
Step 8: Preaparing the Wiring.
1. Utilizing an old phone cord, the red and black wires were striped out and prepped to be used on the box.
**Info Note** The wiring itself can actually act a resistor. if the wire is thick and is a long piece there is more resistance to the current (water) flow so not as many electrons flow to the light. Therefore the light is dimmer than we would like.
2. In order to reduce resistance, the wires in a telephone cord were used. Telephone cord is solid copper and is very small.
**Info Note** Solid wiring transfers electrons more easily than braided wire, like speaker wire for example. Couple that with the low voltage we are using and the very small size of the wire reducing resistance even further so we get the best flow we can.
3. As you can see in the picture below Holly has to drilled two holes in opposite sides of the box (one hole on each side). These holes will route one positive wire and one negative wire. Remember again the red wire is Positive "+" and the black wire is Negative "-."
See all of the pictures below
Step 9: Soldering the Switch Wires.
1. Now that the switch and light holder have been installed it is time to solder the Positive and Negative wires. Predetermine which side of the monetary switch is gong to be positive and which will be negative.
'**Safety Note*** Once again use eye protection.
Using your resin core solder and your soldering gun position your material to be soldered into a clean work area. (As you may have noticed it is not on the kitchen table, but now is on the kitchen counter. Still not the best choice of locations to solder. Perhaps using some type of place mat would help prevent any burns to your counter; luckily we did not have any burns.
2. With safety glasses in place heat the soldering gun element and melt a little solder to your soldering tip. **Safety Note***be careful not to burn yourself.
3. Next place Red Positive wire on the terminal of the switch, make sure your soldering gun is hot and then rub some of the solder on to both the wire and the terminal making them stick together.
4. Once complete with the Red/Positive wire do the same thing with a short piece of the black wire. Make sure it is long enough to reach the positive terminal of the LED. If you need more solder just do as before and add some solder to the soldering gun tip.
**Info Note** The positive side of the LED is the longer leg coming out of the LED itself.
5. Now solder the short black wire from the switch to the Positive leg/side of the LED.
6. Finally solder a longer piece of the Black/Negative wire to the other LED leg/side.
7. Let all solder cool to the touch.
See all of the pictures below for examples.
Step 10: Adding Alligator Clips.
In this short step we will ad the alligator clips to the project box Positive and negative wires.
1. Strip the end of both the Positive and Negative wires.(about 1.25 inches)
2. The remove rubber insulation from the alligator clips and slide each one on its respective wire color.
3. You will notice that each clip has little tabs on the back end. All you have to do is place you wire next to each tab and bend the tab over.
In step 13 you will learn about checking for continuity. After you learn how to perform a continuity check, check for it within the switch box and wires.
Step 11: Assembling the Switch Box
1. Now that the switch and LED holder and LED have been installed and the wires have been soldered it is time to assemble the box.
If you remember in step 8. Holly drilled holes in each side of the switch box to route the wires through the side of the box.
2. Route the red wire through its respective side that it is closest to, then do the same with the black.
3. Now add a touch of hot glue to the solder points to help keep them in place as well as to insulate.
4. You can also add some hot glue to the wires where they go thorough the hole in each side of the box. Doing this will help immobilize the wires if they are pulled on.
5. After the hot glue has cooled position the lid of the box on top of the box and screw in the 4 screws to secure it.
See the pictures below for an assembled box.
Step 12: Making the Electrode Leads.
It is time to make the electrode leads.
**Info Note** What is an electrode? An electrode is a conductor through which electric current is passed and comes in many forms. Here you find out how Holly made hers and you can learn to make your own.
1. Gather your 4 pennies (copper/zinc), grab your drill, and a small drill bit. Your drill bit should twice the size of the phone wire used after it has been stripped (or that general size).
2. Drill a hole through all of the pennies, except 1, near the edge. **Safety Note** Don't forget to use your center punch as well as safety glasses.
3. Now you can use the extra wires from the phone cord that was stripped earlier.
3.1 Collect your pennies and your wire. Strip one end of a wire bare (about 1 inch) and insert it into the hole of the penny try to loop it through the hole again and then twist the bare wire and the insulated part together to tie them off.
3.2 Next use your "Elmer's Blue Bull Polly Glue" (use safety glasses) and glue the wires together. You can do this by directly squirting glue on to the wires or use your "Acid Brush" to paint the glue on (which is what Holly did). It is a lot easier to use the acid brush and a lot cleaner.
3.3 Repeat this until all pennies have a wire attached. **Info Note** One penny will be unaltered, 3 will have both cotter pins and wires.
4. Grab your cotter pins
4.1 After the glue has dried on the pennies, wire strip the other end of the wire bare about 1 inch.
4.2 At this point take the bare wire and a cotter pin and weaver the bare wire though the head of the cotter pin.
4.3 Next try to wedge the bare wire (all the way up to the insulation of the wire) underneath the head of the cotter pin between the legs of the cotter pin.
4.4 Now neatly wrap the wire around the cotter pin neck keeping each roll flush to the next (just for neatness and conductivity).
4.5 Almost done, take the wire and bring it up between the legs of the cotter pin to wedge the wire again.
4.6 Final step, again use your "Elmer's Blue Bull Polly Glue" and glue the wire to the cotter pin. Holly put glue over each roll of the bare wire also to help keep it in place. Again, Holly used the Acid brush to apply the glue.
5. Repeat this step to make 2 more of the cotter pin electrodes.
6. Keep one cotter pin separate we will use it later.
See all of the pictures below
Step 13: Electrode Test
Now it is time to test the electrode for continuity.
**Info Note** What is continuity? When an electrical circuit is capable of conducting current. Or if we go back to our waterfall analogy from earlier it means that the flow can travel down the river. In this case the river is a penny, a wire, and a cotter pin. In order to test for continuity we use a multimeter.
1. Set your multimeter to ohms and if it has a audible beep use it also.
1.1 Turn on your multimeter and place the black lead of your meter on one end of the electrode then while holding it in place touch the red lead of the meter to the other end of the electrode. If you are using a digital multimeter you will get zero ohms and an audible beep (if you have that feature on).
2. Repeat test for each electrode.
3. If everything checked out and is working good you are ready to move on to the next step. If not go back and check to make sure that the connection to the penny and the cotter pins are tight. Then retest and repeat until you have solved the problem then continue to the next step.
We still need to check for continuity in our switch box. The procedure is the same but this time in order to get continuity you have to press the momentary switch. If you get continuity the result is the same as the previous check. If you do not get continuity then retest, if still no continuit you must remove the box lid and check the soldering on the wires and fix it until you get continuity.
See all of the pictures below.
Step 14: Project Mounts
In order to keep our project from rolling all over and make it look presentable we need to make mounts.
In order to accomplish this Holly used (2) 2 Inch x 4 inch PVC couplings cut in half.
1. Put on you safety glasses
2. Measure to the center of the PVC coupling slowing begin to cut until you have a nice grove the saw away making sure that you keep a straight line, the best that you can that is.
3. Once you have all four pieces you are ready to mount them on the project board.
4. This is easy, you can select any formation you like but Holly chose a half circle in order to show a orderly pattern.
4.1 Grab you "Elmer's Polly Glue" again as well as another acid brush and paint some glue on to one side of the the mounts.
4.2 Now place your mounts on your project board with the glue edges touching the board. Now wait for the glue to cure and you are ready for the next step. Holly also used double sided tape to hold the switch box down.
See all of the pictures below.
Step 15: Power Check Testing 1 2 3
Time to test our battery power.
1. Grab the multimeter again.
2. Set your meter to volts.
3. Select a lemon.
4. OK now stick each of the meters electrodes into opposite sides of a lemon.
5. The meter should display a voltage reading. One of Holly's lemon's measured .237 volts.
This is not enough to power our 3 volt LED, not even slightly.
6. Lets test another lemon. Wow! .565 a half of a volt! That's pretty good.
7. Now pre-check all 4 lemons hooked together and see what voltage reading you get.
Holly had the following readings:
7.1 Check 1 2.946 Volts!
7.2 Check 2 2.953 Volts!
7.3 Check 3 2.967 Volts! We have a winner.
8. BUT is 2.967 volts powerful enough to light a 3 volt LED? Take a minute and look at all the resistance that it has to overcome; the wires, the pennies, the cotter pins, the switch, and even the little bit of solder we used to connect the wires, everything has to be factored in. The voltage has to travel though each of these items and each of these items add resistance. Will it work??
See all of the pictures below.
**Info Note ** By the way the alligator clips (in some of the pictures) from the switch box are only being used to secure the leads from the multimeter, actual voltage is not going through the box at this time.
Lets move on to the next step
Step 16: The Moment of Truth
In the last step we found we had a total of 2.967 Volts and we asked the following questions:
"Is 2.967 volts powerful enough to light a 3 volt LED? Look at all the resistance that it has to overcome the wires the pennies, the cotter pins, the switch, and even the little bit of solder we used to connect the wires, everything has to be factored in the voltage has to travel though each of these items and each of these items add resistance. Will it work"?
It is time to find out. Use the pictures below if you are confused on placement of the single penny, the single cotter pin, or the electrodes.
1. Starting in a clockwise direction place the first lemon in its mount/holder. On the front side make a small slice in the lemon peal and push an unmodified penny into the slice. On the back side of the lemon insert a cotter pin electrode (with wire attached) about 3 quarters into the lemon.
2. Second, place the next lemon in its mount/holder. Make a slice along the side of the lemon just big enough for the penny to be pushed into. Now push the penny attached to the electrode from the first lemon into the slice of the second lemon. now the first and second lemons are connected in series.
3. Third, take a modified cotter pin electrode and insert it into the back side of the second lemon. Now place the third lemon in its holder/mount and cut a slice in it for the penny electrode. Slide in the free hanging penny electrode connected to the backside of the second lemon. now the first, second, and third lemon are all connected in series.
4. Using you last cotter pin and penny electrode insert the cotter pin side into the back side of lemon three, Next make a slice on the backside of lemon 4 and slide the free hanging penny electrode into the slice.
5. OK remember back in step 12.6 I told you to keep one unmodified cotter pin. Take that cotter pin and insert it into the front of lemon 4.
6. Now that all pennies and cotter pins are in place connect the Positive side alligator clip to the unmodified penny on lemon 1. Connect the negative side alligator clip to the unmodified cotter pin on lemon 4. Now we are all set
it is the "The Moment of Truth".
7 Push the momentary switch button and...
YES IT WORKS!!!!!!!!!!!!!!!!!!!!!!!!!
Our hypothesis is correct. (Will 4 lemons have enough current (moving force) to light a L.E.D. light? With the lemons connected together, with a metal wire attached to electrodes on each side of the lemons, an average of about 3 volts should be registered. This is enough to enable the light to come on".
Step 17: Hmmmm....What If????
Now we know 4 lemons have enough "Juice" to power our LED. Do we have anything else that we can try?
Step 18: Tator Time
So we have these old rotten potatoes... do you think??? Yeah lets give it a shot.
These potatoes are so old they have eyes growing from them.
1. We hook up the meter and we get a reading of 3.625 Volts and 3.629 volt!
2. That's .662 volts more than the lemons and these are old potatoes!
3. You can even tell the difference in the light intensity, it's brighter.
Look at the pictures below.
Step 19: Follow on Actions, Conclusions, Thoughts, Other Lessons Learned and Input From Others.
We will take this opportunity to cover follow on actions, consider the conclusions and record some final thoughts.
1. Follow on actions: While there are no pictures to post of this follow on action it should be known that it did occur. Holly went on to connect the lemons and potatoes together as a final test, she even added a tomato into the line. Amazingly she obtained a higher voltage and the LED got brighter as she added more items to the Bio Battery.
2, Conclusion: The hypothesis was correct an LED can be powered by 4 lemons or 4 potatoes or a mixture of all plus a tomato.
3. Final thoughts to consider. After the experiment was concluded the potatoes were thrown in the garbage. They could have been replanted to grow more potatoes (future instructable perhaps), thrown in a compost bin or even boiled to make mashed potatoes and have them for dinner. However time did not permit any of these actions so they were thrown in the garbage.
In the end the lemons used in this instructable were used to make lemonade, and they tasted great, they made a cool refreshing drink.
4. How could this Bio Battery be used to power future items as an alternative power source?
4.1 Perhaps power a 12 volt fan with an entire sack of potatoes to cool you off while your making lemonade.
4.2 Run our 9 volt alarm clocks.
4.3 Power book lights/reading LED lights.
4.4 What if we literally had a field of potatoes connected in series while they were still planted in the ground. How long would they last, would they go bad? How much power could we obtain?
In the end we have found that this BIO BATTERY is a multi-use power source. We may be able to power our equipment and our bodies with the same power source, but not at the same time. Even after digestion it may be used to create methane gas or fertilize new crops (or both).
OtherLessons Learned: This instructable was about powering an LED with lemons. However it also instructs a basic idea of electrical flow, introduces new terms, couples items to create a switch box and electrode leads and has allowed the opportunity of using hand tools. This lesson starts a basic foundation to build from for future projects.
Thank you for reading this Instructable. Please feel to leave feed back on how we could have made this better.
1 We know we could use more close up shots.
2. Add video clips.
Thank you to those who have :Submitted ideas for this projects improvement
thecheatscalcs - "try adding some voltage amplifying circuits, you might be able to power even more stuff!"
T3h_Muffinator' - for starting a "Kids in Science and Engineering" group.
T3h_Muffinator - Perhaps try and emulate the environment of a lemon in...say... a beaker or water bottle. Then, you don't use the recyclable lemon skin or pulp, which you could turn into paper, and you're only using the necessary metals in acid. (try vinegar!)
Andrew546 - for identifying an odd and misunderstood statement regarding safety glasses.
moep- for identifying my incorrect usage of the word "allot"
Also thank you to everyone that provided positive and courteous feedback.
Finally, remember most of the items in this insrtructable can be found on AMAZON.COM