Summary of Tiny AVR Microcontroller Runs on a Fruit Battery
Some fruits and vegetables can serve as electrolytes to make primary cells using metal electrodes. This project builds a lemon-based battery (copper and zinc electrodes) to power an AVR microcontroller. Using PCB copper islands and zinc strips from 1.5V cells, lemon halves are placed on islands and zinc inserted to form multiple cells. The resulting fruit cells produce about 0.9 V each; total current depends on electrode surface area and electrolyte quality. A low-voltage AVR (e.g., Tiny13V) can run from the fruit battery wired on a breadboard.
Parts used in the Fruit Battery AVR Project:
- Lemons (electrolyte)
- Bare copper PCB (for copper electrodes and islands)
- Zinc strips (extracted from 1.5V AA cells)
- Galvanized nails (optional zinc electrode)
- Solder wire
- Sandpaper
- Wire
- File or hacksaw (to cut PCB islands)
- Breadboard
- AVR microcontroller (example Tiny13V)
- Connecting leads and basic components for AVR circuit
Some of the fruit and vegetables we eat can be used to make electricity. The electrolytes in many fruit and vegetables, together with electrodes made of various metals can be used to make primary cells. One of the most easily available vegetable, the ubiquitous lemon can be used to make a fruit cell together with copper and zinc electrodes. The terminal voltage produced by such a cell is about 0.9V. The amount of current produced by such a cell depends on the surface area of the electrodes in contact with the electrolyte as well as the quality/type of electrolyte.
The AVR microcontroller is a leading low power microcontroller that has been around for almost a decade now. Recently, new lower power devices have been added to the AVR family, called the PicoPower AVR microcontrollers.
In this instructable, we show how even the regular AVR devices can be set up and programmed to run off a fruit battery.
Step 1: Preparing the Fruit Battery
For the battery, we need a few lemons for the electrolyte and pieces of copper and zinc to form the electrodes. For the copper, we just use a bare PCB and for the zinc, there are a few options: use galvanized nails or zinc strips. We chose to use zinc strips extracted from a 1.5V battery.
Start with a piece of bare PCB. The size of the PCB should be large enough so that you can create 3 or 4 islands on it. Each island will be used to place a half cut lemon on it.
Step 2: Prepare the Zinc Electrode
Next, open up a few 1.5V AA size cells for the zinc strips and clean it up with sand paper and solder wire to each strip.
Step 3: Arrange the Electrodes
Step 4: Add Lemons to the Electrodes
Step 5: Assemble the AVR Tiny MIcrocontroller Circuit
Wire the circuit diagram shown here on a bread board. The choice of V type of AVR is important. For example Tiny13V is very appropriate for such an experiment, since V type of AVR is rated to work down to 1.8V power supply voltage.
For more detail: Tiny AVR Microcontroller Runs on a Fruit Battery
- What metals are used as electrodes in the lemon cell?
Copper (from a bare PCB) and zinc strips (from 1.5V cells) are used as electrodes. - How much voltage does a single lemon cell produce?
The terminal voltage produced by such a cell is about 0.9V. - How is the zinc electrode prepared?
Open 1.5V AA cells to extract zinc strips, clean them with sandpaper, and solder wire to each strip. - How are the copper islands made on the PCB?
Cut islands on the bare copper PCB using a file or hacksaw and solder wires from zinc strips to each island. - How are lemons arranged on the electrodes?
Place half-cut lemons on each copper island with cut face down and make incisions to insert the zinc strips. - What determines the current produced by the fruit cell?
The current depends on the electrode surface area in contact with the electrolyte and the quality or type of electrolyte. - Which AVR microcontroller is suitable to run from a fruit battery?
Tiny13V is appropriate because it is rated to work down to 1.8V supply voltage. - How are multiple fruit cells connected for higher voltage?
The article shows using multiple cells (each with one lemon half, copper island, and zinc strip) arranged together to increase total voltage.
