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The well known "lemon battery" uses an acid to dissolve zinc and release electrons which flow back into the solution to form hydrogen gas.

These batteries are quite weak by comparison to store bought batteries, but it can be a useful learning tool.

Why are these batteries weak? In part, it is due to the chemical reaction and metals, but I wanted to squeeze every bit out of this battery concept by reducing the distance between zinc and copper, and increasing the surface area of both. To do this, I created stranded, coiled, wire and used a shoelace as a barrier between the metals, also serving as a permeable substrate for the electrolyte, vinegar.

Three cells in series produced 2.4V and illuminated a small LED, although current was very low. Production of hydrogen gas was very noticeable.

I wanted to share these methods with you in the hopes that this construction technique inspires other projects.

I was particularly fond of the lemon battery instructable by madaeon linked here: https://www.instructables.com/id/The-micro-Lemon-Battery-reusable-1-hour-of-led-l/

Step 1: Materials and Tools

The battery needs Zinc, Copper, and an acid.

For the zinc, I researched online and found that galvanized metal should be coated in zinc. Unfortunately, the wire packaging doesn't directly state that it is zinc, but I think it is. Galvanized steel wire functions as a source of zinc.

Copper wire can easily be found in most craft and hardware stores.

I chose to use white distilled vinegar for the acid, because there aren't any additional molecules of sugar or salt to think about.

To keep the two types of wire close but not directly touching I suggest shoelaces. They will absorb the electrolyte, but maintain a small distance between the metals.

For tools: I needed scissors, wire cutters, an electric drill, and a C-clamp.

Step 2: Creating Stranded Wire

Take about 20 feet of wire and loop it around your clamp. Insert the two free ends into the chuck of your electric drill and tighten them down. Spin the wires together to form stranded wire. Repeat with both wire types.

Strand the copper wire an additional two times to thicken it up. This will become the core of our hollow shoelace.

Step 3: Coiling the Wires Into a Cable

Cut one end of the shoelace and insert the thicker copper stranded cable into the hollow shoelace.

Push the copper cable all the way in, hopefully you have some excess at the end, otherwise you'll need to keep some exposed so you can make an electrical connection later.

Begin wrapping the galvanized cable around the shoelace with copper core. Wrap the entire thing until you reach the end.

Now, we have a large amount of zinc and copper ready to react with very little distance between them, but not touching. The shoelace will absorb the acid.

To save space, over coil the cable in on itself or wrap it around itself. You can be as creative as you like here, just remember that the exposed copper and one end of your galvanized wire are our connection leads to measure the voltage.

Step 4: Electrical Tests

As you can see from the images, without any acid, the coils produce no voltage. Once the acid is added, each cell produced ~1 volt and all three in series produced > 2 V.

In the closeup image, note the gas bubbles rising. This is hydrogen gas, and these coils produced a lot of it, continuously. There could be a project in here...

Lastly, check the multimeter set to current measurement. This is the current in a short circuit. Max, 40 micro Amps. I was able to illuminate a blue LED with these three cells as a battery.

<p>I think this is interesting. What would happen if you rotated the coil in the electrolytic or rotated the electrolytic around the coil? </p>
Thanks for your interest barrycdog. Those could be some good alterations. One thing I discovered while doing this is that the reaction creates a lot of gas which forms bubbles all over the metal. This probably slows down the reaction as they tend to just stick. I am left wondering if there is a way to clear these bubbles as they are formed to keep the reaction up. Then again, maybe we could try these construction techniques with totally different types of battery reactions.
<p>How many of these would I need to put in series to start an RV stranded in the desert?</p>
<p>PKM is spot on. I think you are better off looking into solar panels and super capacitors if you need an emergency car starter.</p>
<p>Gadzooks! I wasted all my money on all these shoelaces and jars! Now what do I do? I'll build a shweet hanging garden. Ah, wait, my RV is still stuck...</p>
<p>In series? The author states &quot;three cells in series produced 2.4V&quot;, and you'll want 12V to start your engine, so you'd need five times as many, or fifteen cells.</p><p>However!</p><p>The author also states that the cells produced about 40 microamps. I thought that was a typo but looked at the photo, and the multimeter is definitely set to the microamp range. To start a car engine you need a current of something like 100A, which means you'd need (100/0.00004) = 2,500,000 of these jars in parallel with each other, or 37,500,000 in total. That's a lot of jars.</p>
<p>So you're saying there is chance it could work? :)</p><p>My inquiry was kind of a joke. There was an episode of 'Breaking Bad' where the character's RV was stranded in the desert and they had to make homemade chemical batteries to jump start it.</p>
How long would it produce energy if pure acid was available all time?
<p>The limiting reagent is the Zinc. The more zinc you have, the longer this battery will last. You could try and hunt down pure zinc wire, or look into a design that uses zinc plates. Galvanized steel is mostly steel, just plated in a thin layer of zinc.</p>
Does length affect voltage? Have you tried other acids or concentrations?
<p>The voltage is more a product of the chemistry. It maxes out at 1V. The current capacity of the battery would increase with length / more metal.</p>

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Bio: My name is John Espey. I am a videographer and artist in the San Francisco Bay Area. All my life I have loved ants and ... More »
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