10 ways
Ten ways to make a battery
by Joe Miller
Each one with a picture, a parts list, step-by-step directions, what to expect, how long it lasts and how to stay safe. A cheap multimeter (about $15) makes every project more fun: you can watch the voltage.
Safety first. Homemade cells are low-voltage and low-risk, but wear safety glasses, wash your hands, keep chemicals and small parts away from children and pets, and never eat the fruit or vegetables you used. Never try to build or rebuild lithium or lead-acid batteries at home, and never try to recharge a battery that isn't made to be recharged.
How long they lastShopping list1. Lemon battery2. Potato battery3. Coin stack4. Salt-water jar cell5. Aluminum-air cell6. Earth battery7. Vinegar jar8. Daniell cell9. Magnesium salt-water cell10. Mud battery
How long each battery lasts
Homemade batteries make very small amounts of power, measured in thousandths of an amp (mA). They run an LED, a clock or a small sensor, not a phone or a light bulb. The less you draw from them, the longer they last.
| Battery | Lasts about | What ends it |
|---|---|---|
| 1. Lemon battery | 2 to 4 days, until the lemon dries out | The lemon dries out |
| 2. Potato battery | About a week; boiled potatoes give more power but spoil sooner | The potato spoils (boiled ones give more power but spoil sooner) |
| 3. Coin stack (voltaic pile) | A few hours, until the paper dries; re-wet it to restart | The soaked paper dries; re-wet it to restart |
| 4. Salt-water jar cell | Weeks to years, depending on the load (see the bucket battery) | Depends on the load; the zinc is slowly used up |
| 5. Aluminum-air cell | Hours to a day, until the foil is eaten through | The foil is eaten through |
| 6. Earth battery | Months; it keeps going as long as the soil stays damp | Keeps going while the soil stays damp |
| 7. Vinegar jar ("Baghdad battery") | Days to weeks | The vinegar weakens and the metals corrode |
| 8. Daniell cell (gravity cell) | Weeks with care | The chemicals need topping up |
| 9. Magnesium salt-water cell | Weeks; replace the magnesium as it wears away | The magnesium wears away; replace it |
| 10. Mud battery (microbial fuel cell) | Weeks to months, fed by bacteria | Runs as long as the bacteria in the mud stay alive |
| 5-gallon bucket battery | Up to decades: about 35 years at 8.6 mA, about 300 years at 1 mA | The 4 kg zinc plate is slowly used up; needs water topped up and sludge scraped |
Shopping list: supplies for all ten
Almost everything comes from a grocery store, a hardware store and one online order. Prices are typical U.S. prices in 2026 and vary by store.
| Supply | Used in | Where to get it | Typical cost |
|---|---|---|---|
| Lemons, potatoes | Lemon, potato | Any grocery store | A few dollars |
| White vinegar, table salt, aluminum foil | Coin stack, salt-water jar, aluminum-air, vinegar jar, magnesium | Grocery store | $1 to $4 each |
| Galvanized (zinc-coated) nails, large iron nails | Lemon, potato, vinegar jar | Hardware store nail aisle (Home Depot, Lowe's, Ace, local hardware) | About $4 a box |
| Copper strip, wire, pipe or roof flashing | Most projects | Hardware store plumbing, electrical or roofing aisle; craft copper sheet at Hobby Lobby or Michaels | $5 to $15 |
| Zinc strip or zinc washers | Coin stack, salt-water jar, Daniell cell | Hardware store (roofing "zinc strip", washers), or a marine store ("zinc anode") | $5 to $15 |
| Pennies | Coin stack, lemon | Your change, or a bank; post-1982 pennies are copper-plated zinc | Pennies |
| Activated charcoal | Aluminum-air | Pet store or Walmart aquarium section (filter carbon) | $5 to $10 |
| Copper sulfate | Daniell cell | Hardware or garden store, sold as root killer (label must say copper sulfate) | $10 to $20 |
| Magnesium bar | Magnesium cell | Camping fire starter: Walmart, sporting goods stores, Amazon | $5 to $10 |
| Galvanized pipe, copper pipe or ground rod | Earth battery | Hardware store plumbing and electrical aisles | $10 to $25 |
| Carbon felt or a mud battery kit | Mud battery | Online (Amazon) or a science or toy store (for example, the MudWatt kit) | $30 to $50 for a kit |
| Alligator-clip test leads | All | Amazon, Walmart, Harbor Freight, Micro Center | $5 to $10 a pack |
| Red LEDs, small LCD clock or calculator | All | Amazon, Micro Center, Adafruit or SparkFun online; LCD clocks at dollar stores | $1 to $8 |
| Digital multimeter | All (to measure volts) | Harbor Freight, hardware stores, Walmart, Amazon | $10 to $25 |
| Safety glasses and gloves | All, especially Daniell | Hardware store | $5 to $10 |
Tip: buy one pack of clip leads, a few LEDs and a cheap multimeter first; they work for every project on this page.
1. Lemon battery
⚡ 0.9 VCurrent: about 0.1 to 0.5 mALasts: 2 to 4 days, until the lemon dries outEasy, 15 minutes
Supplies, where to get them, and cost
| Supply | Where to get it | About |
|---|---|---|
| Lemons (4) | Grocery store | $3 |
| Galvanized nails (box) | Hardware store (Home Depot, Lowe's, Ace), nail aisle | $4 |
| Copper strip or heavy copper wire | Hardware store (Home Depot, Lowe's, Ace), plumbing or electrical aisle | $5 |
| Alligator-clip test leads (pack of 10) | Amazon, Walmart or Harbor Freight | $6 |
| Red LEDs (pack) | Amazon, Micro Center or Adafruit | $3 |
| Digital multimeter (optional, reusable) | Harbor Freight, Walmart or hardware store | $10 to $25 |
Total for this battery: about $15 to $20, plus a multimeter if you want one. Clip leads, LEDs and a multimeter can be reused for every project. Prices are typical 2026 U.S. prices and vary by store.
Steps
- Roll each lemon firmly on the table to break up the juice cells inside.
- Push a galvanized nail into one side and a copper strip into the other, about 2 inches apart. They must not touch.
- Measure: you should see about 0.9 volts between them.
- Wire 4 lemons in series: copper of one lemon to the zinc of the next.
- Connect the last copper to the LED's long leg (+) and the first zinc to the short leg (−).
Why it works: Any two different metals in an acid make a cell. Zinc gives up electrons more easily than copper, so it becomes the negative side.
Safety: Throw the lemons away afterward: zinc and copper salts get into the fruit.
2. Potato battery
⚡ 0.8 to 0.9 VCurrent: about 0.2 to 1 mA (more if boiled)Lasts: About a week; boiled potatoes give more power but spoil soonerEasy, 15 minutes
Supplies, where to get them, and cost
| Supply | Where to get it | About |
|---|---|---|
| Potatoes (2 to 4) | Grocery store | $3 |
| Galvanized nails (box) | Hardware store (Home Depot, Lowe's, Ace) | $4 |
| Copper strip or wire | Hardware store (Home Depot, Lowe's, Ace) | $5 |
| Alligator-clip test leads (pack of 10) | Amazon, Walmart or Harbor Freight | $6 |
| Small LCD clock or calculator | Dollar store or Walmart | $1 to $5 |
| Digital multimeter (optional, reusable) | Harbor Freight, Walmart or hardware store | $10 to $25 |
Total for this battery: about $15 to $20. Clip leads, LEDs and a multimeter can be reused for every project. Prices are typical 2026 U.S. prices and vary by store.
Steps
- Optional: boil the potatoes for about 8 minutes and let them cool. Researchers found this greatly increases the power.
- Cut each potato in half or into thick slices: each piece can be its own cell.
- Push in a zinc nail and a copper strip about 1 to 2 inches apart in each piece.
- Wire 2 pieces in series for a 1.5-volt clock, or 3 to 4 for an LED.
Why it works: Same chemistry as the lemon. The potato is just a cheap, solid container of electrolyte, and slices give you many cells from one potato.
Safety: Don't eat the potatoes afterward.
3. Coin stack (voltaic pile)
⚡ about 0.7 V per coin pairCurrent: about 0.5 to 1 mALasts: A few hours, until the paper dries; re-wet it to restartEasy, 30 minutes
Supplies, where to get them, and cost
| Supply | Where to get it | About |
|---|---|---|
| 10 pennies | Your change jar or a bank | 10 cents |
| Zinc washers (if using older pennies) | Hardware store (Home Depot, Lowe's, Ace) | $3 |
| Sandpaper | Hardware store (Home Depot, Lowe's, Ace) | $4 |
| White vinegar and salt | Grocery store | $3 |
| Cardboard or paper towel, tape | At home | $0 |
| Alligator-clip test leads (pack of 10) | Amazon, Walmart or Harbor Freight | $6 |
| Red LEDs (pack) | Amazon, Micro Center or Adafruit | $3 |
Total for this battery: about $10 to $15. Clip leads, LEDs and a multimeter can be reused for every project. Prices are typical 2026 U.S. prices and vary by store.
Steps
- Sand the copper off one side of each modern penny so the zinc shows.
- Cut small circles of cardboard and soak them in vinegar with a spoonful of salt.
- Stack: penny (zinc side down), wet cardboard, penny, wet cardboard, and so on. Don't let the cardboard touch the coin above it around the edges.
- Tape the stack loosely. Touch wires to the top and bottom coins: about 0.7 volts per layer.
- 5 or 6 layers will light a red LED.
Why it works: Each penny is a two-metal cell by itself once sanded: zinc on one face, copper on the other. Stacking them adds the voltages.
Safety: Defacing a few pennies for a science project is not a crime, but keep the stack away from small children.
4. Salt-water jar cell
⚡ 0.9 to 1.0 VCurrent: a few mALasts: Weeks to years, depending on the load (see the bucket battery)Easy, 20 minutes
Supplies, where to get them, and cost
| Supply | Where to get it | About |
|---|---|---|
| Glass jar | Kitchen or dollar store | $1 to $3 |
| Salt | Grocery store | $1 |
| Zinc strip | Hardware store (Home Depot, Lowe's, Ace), roofing aisle ("zinc strip"), or a marine store ("zinc anode") | $8 to $15 |
| Copper strip or roof flashing | Hardware store (Home Depot, Lowe's, Ace), or Hobby Lobby or Michaels (craft copper) | $5 to $10 |
| Alligator-clip test leads (pack of 10) | Amazon, Walmart or Harbor Freight | $6 |
| Digital multimeter (optional, reusable) | Harbor Freight, Walmart or hardware store | $10 to $25 |
Total for this battery: about $20 to $35. Clip leads, LEDs and a multimeter can be reused for every project. Prices are typical 2026 U.S. prices and vary by store.
Steps
- Dissolve the salt in warm water and fill the jar.
- Hang the zinc and copper strips on opposite sides of the jar, not touching. Bend the tops over the rim.
- Keep the clip connections above the water.
- Measure about 0.9 to 1.0 volts. Two jars in series run a 1.5-volt clock for a very long time.
Why it works: The same cell as the lemon, but with a big, refillable electrolyte. Make it bigger and you get the 5-gallon bucket battery.
Safety: Salt water corrodes tools; rinse everything afterward.
5. Aluminum-air cell
⚡ about 1.0 VCurrent: up to several mA: one of the strongest homemade cellsLasts: Hours to a day, until the foil is eaten throughMedium, 30 minutes
Supplies, where to get them, and cost
| Supply | Where to get it | About |
|---|---|---|
| Aluminum foil | Grocery store | $4 |
| Activated charcoal (filter carbon) | Pet store or Walmart aquarium section | $5 to $10 |
| Salt and paper towels | Grocery store | $3 |
| Copper wire | Hardware store (Home Depot, Lowe's, Ace), electrical aisle | $5 |
| Alligator-clip test leads (pack of 10) | Amazon, Walmart or Harbor Freight | $6 |
| Red LEDs (pack) | Amazon, Micro Center or Adafruit | $3 |
Total for this battery: about $20 to $25. Clip leads, LEDs and a multimeter can be reused for every project. Prices are typical 2026 U.S. prices and vary by store.
Steps
- Lay down a square of aluminum foil.
- Put a folded paper towel soaked in strong salt water on top. It must cover the foil so the charcoal never touches the aluminum.
- Mix crushed charcoal with a little salt water into a damp paste and spread it on the paper towel.
- Press a copper wire or a strip of copper foil into the charcoal. That is your positive (+) contact; the aluminum is negative (−).
- Squeeze the layers together firmly. Make 3 for a bright LED.
Why it works: Aluminum holds a lot of energy for its weight, and air supplies the other half of the reaction for free.
Safety: The charcoal is messy: work on newspaper and wash your hands.
6. Earth battery
⚡ 0.5 to 0.9 VCurrent: microamps to about 1 mALasts: Months; it keeps going as long as the soil stays dampMedium, an afternoon
Supplies, where to get them, and cost
| Supply | Where to get it | About |
|---|---|---|
| Galvanized steel pipe or rod, 1 to 2 ft | Hardware store (Home Depot, Lowe's, Ace), plumbing aisle | $8 to $15 |
| Copper pipe, 1 to 2 ft, or a copper-clad ground rod | Hardware store (Home Depot, Lowe's, Ace), plumbing or electrical aisle | $10 to $25 |
| Wire and clips | Hardware store (Home Depot, Lowe's, Ace) | $6 |
| Salt (to water the ground) | Grocery store | $1 |
| Digital multimeter (optional, reusable) | Harbor Freight, Walmart or hardware store | $10 to $25 |
Total for this battery: about $25 to $50. Clip leads, LEDs and a multimeter can be reused for every project. Prices are typical 2026 U.S. prices and vary by store.
Steps
- Drive both rods into moist ground, 1 to 3 feet apart.
- Water around them; a little salt in the water raises the output.
- Clip wires to the tops and measure: about 0.5 to 0.9 volts.
- Wire several pairs in series for more voltage.
Why it works: It is a salt-water cell with the ground as the jar. Output rises after rain and falls when the soil dries.
Safety: Call 811 before you drive rods so you don't hit a buried line. Don't salt garden beds you plan to plant.
7. Vinegar jar ("Baghdad battery")
⚡ about 0.5 V (iron) or 0.9 V (zinc)Current: under 1 mALasts: Days to weeksEasy, 20 minutes
Supplies, where to get them, and cost
| Supply | Where to get it | About |
|---|---|---|
| Small glass jar with lid or cork | Kitchen or dollar store | $1 to $3 |
| White vinegar | Grocery store | $3 |
| Copper pipe piece or copper foil | Hardware store (Home Depot, Lowe's, Ace) or craft store | $5 |
| Large iron nail or zinc strip | Hardware store (Home Depot, Lowe's, Ace) | $2 to $10 |
| Alligator-clip test leads (pack of 10) | Amazon, Walmart or Harbor Freight | $6 |
| Digital multimeter (optional, reusable) | Harbor Freight, Walmart or hardware store | $10 to $25 |
Total for this battery: about $15 to $25. Clip leads, LEDs and a multimeter can be reused for every project. Prices are typical 2026 U.S. prices and vary by store.
Steps
- Stand the copper tube in the jar.
- Hang the iron nail in the middle through the lid so it doesn't touch the copper.
- Fill with vinegar.
- Measure about 0.5 volts. Swap in a zinc strip for about 0.9 volts.
Why it works: Vinegar is a weak acid electrolyte. Iron is less eager than zinc to give up electrons, so the voltage is lower.
Safety: Vinegar is safe; the used liquid can go down the drain with plenty of water.
8. Daniell cell (gravity cell)
⚡ 1.1 V, steadyCurrent: a few mALasts: Weeks with careHarder: uses a poisonous chemical
Supplies, where to get them, and cost
| Supply | Where to get it | About |
|---|---|---|
| Two cups or jars | Kitchen or dollar store | $2 |
| Copper sulfate (root killer: label must say copper sulfate) | Hardware store (Home Depot, Lowe's, Ace) or garden center | $10 to $20 |
| Salt and a paper towel (salt bridge) | Grocery store | $2 |
| Zinc strip | Hardware store (Home Depot, Lowe's, Ace) or marine store | $8 to $15 |
| Copper strip | Hardware store (Home Depot, Lowe's, Ace) | $5 |
| Gloves and safety glasses | Hardware store (Home Depot, Lowe's, Ace) | $8 |
| Alligator-clip test leads (pack of 10) | Amazon, Walmart or Harbor Freight | $6 |
Total for this battery: about $35 to $55. Clip leads, LEDs and a multimeter can be reused for every project. Prices are typical 2026 U.S. prices and vary by store.
Steps
- Wearing gloves and glasses, dissolve copper sulfate in warm water in one cup: it turns bright blue.
- Fill the other cup with salt water.
- Put the copper strip in the blue cup and the zinc strip in the salt-water cup.
- Soak a rolled paper towel in salt water and drape it between the cups so it dips into both. This "salt bridge" lets ions pass.
- Measure a steady 1.1 volts.
Why it works: Keeping the copper in its own copper sulfate means fresh copper plates out at the positive side, so the voltage doesn't sag the way plain salt-water cells do.
Safety: Copper sulfate is poisonous if swallowed and irritates eyes and skin. Keep it away from children and pets, label everything, and take the used solution to hazardous-waste collection. Don't pour it outside.
9. Magnesium salt-water cell
⚡ 1.4 to 1.6 VCurrent: several mALasts: Weeks; replace the magnesium as it wears awayMedium, 20 minutes
Supplies, where to get them, and cost
| Supply | Where to get it | About |
|---|---|---|
| Magnesium fire-starter bar | Walmart, sporting goods stores or Amazon (camping section) | $5 to $10 |
| Copper strip, or thick 2 mm pencil leads (carbon) | Hardware store (Home Depot, Lowe's, Ace) or office supply store | $4 to $5 |
| Salt and a jar | Grocery store or dollar store | $3 |
| Alligator-clip test leads (pack of 10) | Amazon, Walmart or Harbor Freight | $6 |
| Red LEDs (pack) | Amazon, Micro Center or Adafruit | $3 |
Total for this battery: about $15 to $25. Clip leads, LEDs and a multimeter can be reused for every project. Prices are typical 2026 U.S. prices and vary by store.
Steps
- Remove any striker and plastic from the magnesium bar and scrub it shiny.
- Hang the magnesium and the copper in salt water, not touching.
- Measure about 1.5 volts. Two cells in series light most white LEDs.
- Fine bubbles on the magnesium are hydrogen: normal.
Why it works: Magnesium gives up electrons even more readily than zinc, so the voltage is higher.
Safety: Keep magnesium shavings away from flame: they burn very hot. Work with good air flow because of the hydrogen bubbles.
10. Mud battery (microbial fuel cell)
⚡ 0.3 to 0.7 VCurrent: microampsLasts: Weeks to months, fed by bacteriaEasy to build, a few days to start
Supplies, where to get them, and cost
| Supply | Where to get it | About |
|---|---|---|
| Plastic food container | Kitchen or dollar store | $2 |
| Mud | Your yard, garden or a pond | Free |
| Carbon felt or graphite cloth (2 pieces) | Amazon | $10 to $15 |
| Or a complete mud battery kit (e.g. MudWatt) | Amazon or science and toy stores | $30 to $50 |
| Tiny LED blinker or capacitor circuit | Included in kits, or Amazon | $5 |
| Alligator-clip test leads (pack of 10) | Amazon, Walmart or Harbor Freight | $6 |
Total for this battery: about $25 (parts) or $30 to $50 (kit). Clip leads, LEDs and a multimeter can be reused for every project. Prices are typical 2026 U.S. prices and vary by store.
Steps
- Bury one carbon piece in the bottom half of the mud: this is the negative (−) side.
- Pack the mud firmly and lay the second carbon piece on top, open to the air: positive (+).
- Connect wires and wait a few days while bacteria colonize the carbon.
- The voltage climbs to about 0.5 volts. A small boost circuit stores the energy and blinks an LED.
Why it works: Certain soil bacteria "breathe" onto metal and carbon surfaces. Research labs use the same idea to power sensors on the sea floor.
Safety: Wash hands after handling mud.
All ten at a glance
| Battery | Volts per cell | Current | Lasts | Cost to build |
|---|---|---|---|---|
| 1. Lemon battery | 0.9 V | about 0.1 to 0.5 mA | 2 to 4 days, until the lemon dries out | $15 to $20 |
| 2. Potato battery | 0.8 to 0.9 V | about 0.2 to 1 mA (more if boiled) | About a week; boiled potatoes give more power but spoil sooner | $15 to $20 |
| 3. Coin stack (voltaic pile) | about 0.7 V per coin pair | about 0.5 to 1 mA | A few hours, until the paper dries; re-wet it to restart | $10 to $15 |
| 4. Salt-water jar cell | 0.9 to 1.0 V | a few mA | Weeks to years, depending on the load (see the bucket battery) | $20 to $35 |
| 5. Aluminum-air cell | about 1.0 V | up to several mA: one of the strongest homemade cells | Hours to a day, until the foil is eaten through | $20 to $25 |
| 6. Earth battery | 0.5 to 0.9 V | microamps to about 1 mA | Months; it keeps going as long as the soil stays damp | $25 to $50 |
| 7. Vinegar jar ("Baghdad battery") | about 0.5 V (iron) or 0.9 V (zinc) | under 1 mA | Days to weeks | $15 to $25 |
| 8. Daniell cell (gravity cell) | 1.1 V, steady | a few mA | Weeks with care | $35 to $55 |
| 9. Magnesium salt-water cell | 1.4 to 1.6 V | several mA | Weeks; replace the magnesium as it wears away | $15 to $25 |
| 10. Mud battery (microbial fuel cell) | 0.3 to 0.7 V | microamps | Weeks to months, fed by bacteria | $25 (parts) or $30 to $50 (kit) |
mA = milliamps, thousandths of an amp. A phone charges at about 1,000 to 3,000 mA, which is why homemade cells can't charge a phone.
Sources
Checked November 11, 2026.