Howto: start a fire with a lemon

boing
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Just wait until the TSA finds out about this!

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“Excuse me sir, can you give me a match in exchange for this lemon?”

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Or get a fire piston…

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  1. Eat lemon in one big mouthful.
  2. Rub some sticks or whatever.
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When life gives you lemons, start an electrical fire in a forest.

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That’s lovely, is that.

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Can’t deny this. Learned more about batteries in DIY electronics books than I ever did in an E-Chem class.

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I want to try this but I suspect it is a hoax. What’s the motive of creating a hoax video such as this one? Traffic?

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Back in the day when microprocessors were mostly nmos and power hungry we designed a data acquisition unit using the RCA 1802 CMOS processor. I was able to power it for a short time using three quarter lemons, three carbon rods and three zinc rods (got about 4V) but the lemon slices had to be squeezed to get enough current out to work the device and a small LED display. Even so, it impressed people.

I think that this could be made to work using a single wire from some steel wool, and by paralleling a number of zinc coated nails and copper boatbuilding nails (roves), then squeezing the lemon to break the cells and free enough acid to get a decent current for a few seconds. But I’m really not going to carry out the experiment.

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If you watch the video, you’ll note that the guy squeezes the lemon right at the beginning. Also, he inserts zinc nails into pre-existing holes in the lemon. Almost as if he’s done it before.
I don’t know how well it works to hook the cells in series like that, since they are all in the same lemon. I’d think there would be a lot of unwanted current pathways there to reduce his power output.

Maybe a better plan would have been to slice into the lemon to separate the cells, and put glass cover slips into the slits. Also, he could inject some copper sulfate around the copper nail holes, so that the chemistry wouldn’t depend on escaping hydrogen there.

But then, how many people keep cover slips and copper sulfate in their camping gear? Maybe not as many as have lemons and zinc and copper nails …

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Yes, I thought it made no sense. As I say, when we did it we separated out three lemon quarters to avoid internal shorts.

However, if you have a phone with a removable battery, and a little steel wool, you are much more likely to get success using that. Even an AAA battery will probably do the job. This does seem to be an example of using a Nutribullet to liquidise a grape.

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When I played with such a battery a while back, it didn’t generate much excitement. I peeled off the covering, to get past the battery’s charge controller (little processor chip that controls current flow), and shorted the terminals together. Turns out that battery had another layer of safety, a strip of some funny kind of metal that became non-conductive when it warmed up a little bit. Nothing exciting happened at all. It barely got warm. Of course, you could take a knife to the cell itself. That might be exciting.

You can get more excitement from a couple of 9v electronics batteries, though. When you change the ones in your smoke detector, try plugging a couple of them together, mating the snaps. When I did this, they got hot so quickly that I didn’t have time to unplug them. They’d probably get hotter if you use new batteries, maybe hot enough to start a fire.

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It’s a kind of PTC thermistor. Purely coincidentally I did a little work on using PTC devices to protect things from lithium batteries, back in 1983.

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But then, how many people keep cover slips and copper sulfate in their camping gear? Maybe not as many as have lemons and zinc and copper nails …

Obviously you’re neither an Eagle Scout, not even a Campfire Girl.

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I keep limes in my camping gear instead. Can’t make a decent margarita without fresh limes.

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Well, they took in Cory and others. Their goal may be to sneer at tech gurus who otta know better.

I did a quick crude test with a bench supply. The extra fine OOOO-grade steel wool needs over an ampere before it glows the least bit. I think a lemon battery needs plates about a foot across before it can produce a couple of amps. But I’d have to actually test this.

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