Is it possible to charge a mobile phone from a lemon?

Im thinking, lots of electrodes in one lemon, joule thief and a capacitor maybe...?

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The answer is YES!
So long as you had enough lemons in series and parallel.

See the actual reaction is not the lemon juice. The lemon juice acts as an electrolytic solution for the two metal electrodes. Typically nickel and copper. If you used better metals like magnesium and copper you would be able to get a high voltage potential and require fewer lemons. I did a project a few years back where we wired lemons together to power a toy car. Its not about how many lemons its about how many electrodes you have. In fact if you took an ice tray and filled it with electrode pairs in parallel and series making sure the electrolytic solution (lemon juice or any other acid) was seperated you would be able to generate a decently high voltage and current for a short while.

I've tested my old LG phone it required 5V 100mA but it would marginally charge. It was sporadic and it required at least 125mA to charge correctly (bad supply). I had designed a 100mA boost regulator in this instructable but it was not sufficient. Check it out if you would like. (I'm also entering the laser cutter contest so feel free to vote)


I also tested a joule thief. The one I designed had a switching frequency of 250kHz. So it does not really boost any power. The average power over time remaining the same. What it really did was in a way peak the power at a fast enough rate to allow your eye to imagine the LED is fully on when in reality it is blinking.

There is a really detailed explanation to how the joule thief works at this site http://www.emanator.demon.co.uk/bigclive/joule.htm
conundrum21428 months ago

Most phones need at least 200mA at 5.1V to even begin charging. I found that with my old antique Nokia 110 it would begin charging from solar (barely) at 150mA but it was very finicky. The best bet is to get 3 ballpoint pens, chop off the unused section and make a spiral electrode using Mg ribbon with a central copper wire connected at both ends and insulated with Superglue (tm). This prevents the sudden loss of power if one of the connections breaks.

Use two copper wires not one, the reason is that hydrogen production limits available current. 3 in series got me 3*2V = 6V OCV which drops down to less than 5V under any sort of load.

DevinM171 year ago

Soon apple can change their logo to a lemon

Have you asked Lemonie? LOL
So True!
You can shove a bunch of electrodes into a single lemon, such as here:


It's not impossible to get the right voltage and amperage to start charging your phone.

BUT... the lemon's going to discharge rapidly. It won't last very long.
I seriously doubt you could, but the actual answer is "it depends". Keep in mind that lemon juice is not some magic substance from which the electrodes suck electricity. It's just a carrier for the metal ions and helps to get them started moving. The electrodes in your lemon battery are actually the important part, in particular the fact that they are chemically dissimilar to begin with but gradually rust away toward equilibrium as the battery is operated. You can improve the battery slightly by increasing the mass and surface area of the electrodes. Ruffled or large numbers of needle-shaped electrodes would have more area.
Just to add another point: Even if you did succeed in getting a useful amount of electricity, the cell phone batteries would still hold more. How do I know this? Lithium batteries aren't cheap. Lemons and tiny bits of metal are. If a lemon with zinc and copper strips stuck in it were a source of electricity with anywhere near the efficiency of a cell phone battery, your cell phone would already have a compartment containing metal discs and lemon slices. : )
sound918 years ago
No, it will not. Almost every cell phone on the market requires 5 volts and 100 miliamps to charge. The reason for this is because it is the standard output for a USB drive. This is also true for any mp3 player. As said by Another Brian, the current would not be high enough.
It's possible to run a car on lemons. The problem would be how many lemons can you lay your hands on. I don't know how much current you can get from a lemon but I would start by measuring it. The only real trick is putting enough of them in series to get the voltage up to whatever you charger normally puts out. I don't think you will be able to make more than one cell per lemon, but I would try to get as much surface area as you can. (Try multiple electrodes wired together in clumps.) I think your main problem will be that the lemon cells won't deliver a lot of current. As soon as you connect the phone the voltage will drop (probably below the needed voltage). You can figure this out by measuring the current your phone is using. You can than figure out the abilities of the lemons by connecting the electrodes through a resistor and measure the current. Measuring the voltage will allow you to multiply them to get watts. Divide the needed watts by the 'lemon' watts and multiply by the number of cells you needed to put in series. You will need a lot of lemons
Chicken22098 years ago
Im thinking not enough energy