New battery said to last decades

[YT2095]

and what you have to remember is with ion type cells is that most are what we call "Sudden death" as in, they`ll work perfectly up until the last minute and then drop off suddenly to practicaly nothing (that`s why it`s a BAD IDEA to use rechargables in a torch when going down Caves!)

[mmalluck]

If the voltage is proportional to the decay rate, then it will drop exponentially!

 

But it's not. As I stated in #23, all of the electrons released by tritium will have an energy potential around 6.5KeV. It doesn't matter if one atom or a million atoms of tritium decaying, they all release electrons at the same potential (6.5KeV). The maximum current, on the other hand, will be proportional to the decay rate.

 

Current is a measure of the number of electrons passing through a given 2D window of wire of known conductivity in a certain amount of time. These electrons are product of the tritium breaking down. So if 100 atoms decay, we'll get 100 electrons traveling through our window of wire. If only one atom decays, then we only get a single electron flowing through our wire (IE an itty bitty small current).

 

Since very few electronics operate around 6kv, I imagine this battery will need some kind of DC-DC converter to turn the output into something more useful.

[Hephaestus]

Tritium is used to power a permant (14 year guarantee) glow keyrings. Also in night vision scopes for guns. Where else is 3H used, and what other fun items are publicly available containing radioisotopes, other than smoke detectors?

[zyncod]

Silly question maybe, but why use tritium gas? Using tritiated water, it seems like you could pack a whole lot more tritium into the same area.

[swansont]

Silly question maybe, but why use tritium gas? Using tritiated water, it seems like you could pack a whole lot more tritium into the same area.

 

You don't need more tritium, and the betas would lose energy travelling through water as they ionize things.

[Mag]

wow, thats awesome

 

imagine switching out portable CD players before batteries!

 

if they made them that small.

not to mention, battery companies would go out of buisness.

 

but, i assume these batteries are very expensive?

 

edit: also, these batteries could be used to powe cars, instead of electric or hybrid cars we could have battery powered cars.

[mmalluck]

Remember even if the player isn't switched on, the tritium is still decomposing and the battery is still running dead.

 

I think the problem with the batteries may be the amount of current they can put out. Lets say we can cram a mole of Hydrogen into a battery (that's 22.4 liter of tritium at STP). That's 6.022*10^23 atoms of hydrogen.

 

Now over a 12 year period half of that hydrogen will decay. That's 3.011*10^23 atoms. Each decaying atom will release one useable electron. So during the 12 years the battery will give off 3.011*10^23 electrons or 7.95651*10^12 electrons every second (on average). Yes, I realize the decay is exponetial, but for the sake of making the numbers easy will assume a linear decay.

 

What is this in terms of current? Amps are measured as coulombs per second. There are 6.2415*10^18 electrons in a coulomb. So our battery can put out about 1.274 * 10^-6 amps. That's a mesely 1.27 microamps if we can capture every electron the tritium releases.

 

You're not going to be cranking a car, running a cd player or powering anything larger than a wristwatch with a measily 1.274 microamps.

 

But wait, I said earlier that the electrons released by tritium will have an average energy of 6.5keV. We can take this into account to help us. We'll assume can put a perfect transformer into our battery to trade off this high voltage for a higher current.

 

Lets say we want our battery to output the standard 1.5v that most disposable cells are. We make the voltage 4333 times lower, but get 4333 times more current.

 

Taking this into account we now have a 1.5v battery that can put out 5.524 milliamps. This is still pretty pathetic as far as batteries go.

 

To get better numbers we'd have to use more tritium. A mole of tritum cost around $60, so to get any considerable current out of this battery we're talking $$$$$. Even if we do spend lots of money on more tritium, my example assumes everything is 100% efficent. Sadly it's not. Not every electron will be captured, nor will the transformer we use to adjust the current.

 

Again, there's no cranking cars, running CD players, or putting the battery companies out of business with this technology. Sorry to be the party-pooper, but the numbers don't lie.

[swansont]

edit: also, these batteries could be used to powe cars, instead of electric or hybrid cars we could have battery powered cars.

 

mmalluck already pointed out why you won't, but a battery powered car is an electric car.

 

Another drawback of the atomic decay battery for many uses is that it isn't rechargeable. You use it in situations where you need a little bit of current for a long time, where you can't put a direct power feed, and continually switching batteries is problematic.

[Mag]

oh ok, thanks Mmalluck, i was thinking in terms of regular batteries.

And i dont know enough to figure out the voltage of decay myself

[mmalluck]

I got the voltage of decay from Wikipedia. Everything else, I just reasoned/calculated out.

[Mag]

oh... well, i'll look it up.

 

Wikipedia rules.

[Thomas Kirby]

Disclaimer: I am not an expert.

 

The term "electron volts" has little or nothing to do with the voltage of the cell in question. It is a measure of the energy that the particle carries, or its kinetic energy. One electron volt equals 1.602 * 10^-19 joules. link

 

An electron that carries 6500 electron volts carries 1.041 * 10^-15 joules. It then takes 9.6 * 10^14 electrons to make one joule of electricity. A half mole of tritium has 6.27*10^8 joules worth of electrons to be emitted. Half of this is about 3.14 * 10^8. 314 million joules equals about 8712 watt hours per gram. Over 12.5 years that is an average of 79 milliwatts, minus inefficiencies. However many milliwatts you get at the beginning, you get half that at the end. It would be safe to say that a battery using three grams of tritium could power an LED lamp or several, or a microcontroller, or a radio continuously for 12.5 years and longer. It could also trickle charge a rechargeable battery. The three gram cell could charge a set of batteries for a Walkman in about a day, give or take.

 

There is one problem. The electrons continually charge the cathode of the battery when there is no load. Again, the energy of the electrons is not directly related to the voltage. The cathode will store a charge until it is drained. Also, if the device is not kept grounded, I don't know how it gets rid of excess electrons.

[swansont]

Disclaimer: I am not an expert.

 

The term "electron volts" has little or nothing to do with the voltage of the cell in question. It is a measure of the energy that the particle carries' date=' or its kinetic energy. One electron volt equals 1.602 * 10^-19 joules. link

 

An electron that carries 6500 electron volts carries 1.041 * 10^-15 joules. It then takes 9.6 * 10^14 electrons to make one joule of electricity. A half mole of tritium has 6.27*10^8 joules worth of electrons to be emitted. Half of this is about 3.14 * 10^8. 314 million joules equals about 8712 watt hours per gram. Over 12.5 years that is an average of 79 milliwatts, minus inefficiencies. However many milliwatts you get at the beginning, you get half that at the end. It would be safe to say that a battery using three grams of tritium could power an LED lamp or several, or a microcontroller, or a radio continuously for 12.5 years and longer. It could also trickle charge a rechargeable battery. The three gram cell could charge a set of batteries for a Walkman in about a day, give or take.

 

Talking about "one joule of electricity" is a bit awkward without context.

 

An electron with 6500 eV is the same as one electron accelerated through a 6500 V potential. It is not, however, equivalent to 6500 electrons accelerated through a 1 V potential.

 

As mmalluck pointed out, you would need a perfect transformer if you want to convert your high voltage current into more current at lower voltage. There is a reason that voltage and current are the relevant quantities for electrical applications, and not just the total energy or power.

[Thomas Kirby]

I am going by the idea that, whatever you use to control the voltage and current, you will get a substantial percentage of the energies of the electron as electrical power. The idealization is that out of 8712 watt hours generated by the decay of the tritium, you get 8712 watt hours of usable electricity. If you only get 10 percent, you get 871.2 watt hours. The actual value is probably somewhere in between.

 

Other stuff happens when you charge a material with electrons, too. Where are the positive charges going to come from to create a flow of current?

[alan2here]

I have a remote control car

It uses a batery disighned to last for hours and drains it in about 10 mins

However you get 10 min's of much power (In my example speed)

 

Could a batery disgned to last decades be used up in a few days alowing me to fly around the world on holiday in my batery powered jetpack?

 

I understand dealing with nuclear waste is a big problem.

This would be a great way to get rid of It.

You may however get some idiot's iradeating themselves by using a saw to open the battery.

[d22k]

I have a remote control car

It uses a batery disighned to last for hours and drains it in about 10 mins

However you get 10 min's of much power (In my example speed)

 

Could a batery disgned to last decades be used up in a few days alowing me to fly around the world on holiday in my batery powered jetpack?

 

I understand dealing with nuclear waste is a big problem.

This would be a great way to get rid of It.

You may however get some idiot's iradeating themselves by using a saw to open the battery.

 

sadly not, as a battery of this kind generates the electricity on the fly.

 

a normal batteries potential energy can be used in many ways, high volts low amps, low volts high amps (as in your case), however, in the case of these batteries the voltage and current stays constant (well for the purposes of this argument), so unfortunately no, no jet pack

[NuclearJay]

The real question is, Can it power a Gameboy? (obviously not, just a cool idea)

 

A hundred milligrams of Pu-238 is able to power a pacemaker, I think it can power a gameboy. The fact that is was used to power pacemakers also proves that it can be safe if the proper isotopes are used. The problem right now is restarting the cease production of these isotopes. I am currently experimenting with Th-232 to see if this could be a viable source of power, so far 30g can produce 0.04W of power.

[JohnB]

I am currently experimenting with Th-232 to see if this could be a viable source of power

 

Young whippersnappers! Using thorium to reanimate dead threads. Back in my day it only took an assistant named Igor and a really good thunderstorm.

[swansont]

Young whippersnappers! Using thorium to reanimate dead threads. Back in my day it only took an assistant named Igor and a really good thunderstorm.

 

Pssst. The secret is throwing the third switch!

[John Cuthber]

A hundred milligrams of Pu-238 is able to power a pacemaker, I think it can power a gameboy. The fact that is was used to power pacemakers also proves that it can be safe if the proper isotopes are used. The problem right now is restarting the cease production of these isotopes. I am currently experimenting with Th-232 to see if this could be a viable source of power, so far 30g can produce 0.04W of power.

Not it can't, or at least not unless you can show where I have got the maths wrong.

The specific activity of 232Th is about 4000 Bq/g

It gives about 4Mev per disintegration.

So Thorium produces about 16000 MeV per gram per second.

That's about 2 nW per gram

So, this guy has resurrected a thread to claim that he can get 40 mW from something that only produces about 60nW (that's milli watts from nano watts)

 

Claiming to get about a million times more power than is available isn't a clever thing to do on a science forum.

Edited May 15, 2012 by John Cuthber