# Use the earth's electrostatic field to charge a car battery?

Here is how you can supposedly charge a car battery using the earth’s electrical field.

Needed:
A piece of sheet metal that is around, say, 1 square meter in size, maybe smaller
A long metal spike
Jumper cables

Set the metal sheet on top of the ladder and the car battery on top of that. Attach the jumper cables to the battery, then one cable to the metal sheet. Attach the other cable to the spike and insert in the ground.

With time the sheet metal – and thus the pole attached to it – will reach the same potential as the earth’s field at the height of the ladder. The other pole is grounded. The difference will be enough to charge the battery.

Does this work? Anyone have first hand experience? I don’t know which pole attaches where because I don’t have any info on the earth’s field, but I am assuming it is on the order of tens-of-volts-per-meter at least. (It would have to be.) I do recall reading something about the earth’s field once in Feynman’s lectures on physics. I’d be interested if someone could provide a link.

Yes, it will work, but the currents are very low so it’s somewhat impractical. The wire in the air will attach to the the (+) terminal and the ground one with attach to the (-) terminal. To get any useful amount of charge, you need to get the aerial up very high, at least 100 feet or so.

Then of course there is the question of being able to get enough current out of the rig to overcome the losses in the conductors, and leakage current through ladder. You must also be able to charge at a higher rate than the battery’s natural self discharge rate.

Then you have to worry about wind loading on the structure. If, as Q.E.D. says, you need a tower at least 100 feet high, that would be a serious problem. You’ll also need some kind of protection against lightning if you intend to leave it running for longer periods.

**Q.E.D.*b, do you have more info about the field? From your post, I gather that the sky is at a higher potential (more positive) than ground. I guess this has to do with lightning transferring electrons out of the sky to the ground worldwide. Do you know what the average gradient is (volts-per-meter)?

You wouldn’t have to put the whole battery up that high. You’d only need to run a wire down to the battery on the ground. We did this with a friend’s 80-meter band antenna tower which was about 75’ high to charge a couple AA NiCds once. Kinda cool.

The earth’s electric field is about 100 volts/meter. But the effective impedance is very high so even with a direct short to ground, the currents are extremely low.

That’s on average, by the way. In a thunderstorm the local electric field can skyrocket to over 15 kV/m.

Does this mean you could, in theory, get a REALLY long spike, run it up a block of flats, and power your flat off it? Beats solar power for sure!

Practically, no. As I said, although the voltage gradient is about 100 V/m, the current gradient is pretty low. It’s too early in the morning yet for me to look up the necessary information and do calculations, but I’d say in order for your scheme to work, you’d need to run a wire up 100 miles or more at the very least to get any usable power. And the FAA might take exception to that.

Hmm…OK. Well, what if I built a space elavator. Any chance that would be big enough to get enough power to run it?

Hmmm. Never thought you could use the earth’s electric field to charge a battery, but I guess it’s possible.

Given that the charging current must be really, really low, I’ve got to wonder: will a car battery really charge up? Remember, there is a natural discharge rate of the battery. In other words, a car battery discharges when it’s just sitting there doing nothing. Would the charging apparatus be able to “keep up?” If using small plates to charge a car battery, my guess is that it would not be able to keep up. But that’s just a hunch…

The rate of it charging is going to depend on the size of the metal sheet - the bigger the sheet, the faster it charges. From hearsay, I am under the impression it only about a day to charge. How long does it take a car battery to discharge in warm weather? Definitely over a week, right?

A day to charge a dead car battery? Using metal sheets suspended in the air?! :dubious:

A car battery has around 50 AH capacity. Therefore to charge it in 24 hours we need 2 amps of current that is a lot of current.

To get any current to flow you have to induce a potential and it has to be a positive potential not negative. Using sheet steel will give you a negative potential. It will cause your current to flow away from your intended path. Toward the sheet steel. Use a sheet of zinc or similar metal. Maybe nickel might work I dont know.

But these grade school science prohects are good for learning physics definately. Is this attempt at charging a battery for your school science fair? What grade are you in?

It is so nice that children take an interest in science. Be sure you ALWAYS use safety equipment around acid. And dont turn down your parents assistance in this project. I do know the smaet children like to do things on there own but parents can be valuable especially if theres trouble.

Have a great fun with your science project, children!

Professor.

I am no physicist but isn’t this what Tesla was trying to do?

Heres another tip for you children from the Professor for your science project.

While you can use a earth common you should know the earth is a big potential easily draining your battery from miles away.

You really dont want to use the actual earth for that teeny tiny battery. A nail pressed against the negative contact is enough of a negative to infuce plenty of current. The nail nailed to a board and then A short piece of wire, about six inches connected to the nail then connected to the negative pole of the battery is a better setup.

And ypu may want to move away from the idea of using metal on the positive potential of the battery. A sheet of fiberglass set in the air tied to the positive pole using a woven fiberglass strip would be more likely to induce a earths static charge on your battey.

And that is your goal. Metal is common easy to find but complex in its nature, especially when it comes to separating the electrons from their bonds. It simply doesn’t. You gotta use nuclear for that to happen.

Lots sa luck.

The professor.

Nonsense.
The electronegativity of the metal has nothing to do with the direction of current flow in an atmospheric current harvester. It’s not a battery.
And, the whole idea is ridiculous. The available current is miniscule.