[QUOTE=Crafter_Man]
Heck if I know. I curl up in a ball, sit in the corner, and suck my thumb when I’m asked any chemistry-related question. Googling “battery chemistry” would probably provided the info, but I’m afraid to do it. 
[/QUOTE]
This talks about the first battery ever created: Galvanic cell - Wikipedia
All primary cells work in a similar fashion. Note that for each electron that flows out of the battery, an ion must flow in the opposite direction inside it.
[QUOTE=beowulff]
In the Semiconductor manufacturing biz, there are ion implanters that use nearly 1/2 million volts! They have very, very long plastic poles with a metal strap on one end to discharge them.
[/QUOTE]
I worked with x-ray imagers in electronics manufacturing (board test). IIRC, they took normal AC (240? 480? I can’t remember), rectified it (converted it to DC), re-converted it to high frequency AC (were talking ~10 kHz or so) and then stepped it up to 160 kV at which point it was again rectified and converted to DC and fed to the x-ray tube cathode. The tube was, of course, under high vacuum, while the tube electronics were in an atmosphere of SF6 (sulfur hexafloride) to prevent arcing. The total current in the electron beam was on the order of 80 microAmps, again IIRC. The electron beam was steered and focused onto a berilium (IIRC) target where a small (point) source of x-rays was created (bremstraulung radiation). The point source was moved (via steering the beam) in a circle 180 degrees out of phase with a counter-rotating digital camera with a high speed/high efficiency scintillator.
Cool machine. The Agilent 5DX.
Always remember and never forget that over 90% of the resistance to electrical flow of the human body is in the skin.
The path, the path, the path. A 6 volt car battery can kill you dead real easy if you poke a finger on each hand so that blood comes to the surface. If those points are put on the + & - post of the battery, you will more than likely almost for sure die… Blood conducts electricity like a mofo… Don’t see many electricians wearing their wedding rings either. Gold and sliver conducts electrons quite nicely also…
Also always unhook the negative post of a battery first and connect it last… Saves on sparks, melted tools and burns…
[QUOTE=GusNSpot]
… 6 volt car battery can kill you dead real easy if you poke a finger on each hand so that blood comes to the surface…
[/QUOTE]
So the story about the sailor and his mulimeter ring true?
[QUOTE=beowulff]
This talks about the first battery ever created: Galvanic cell - Wikipedia
All primary cells work in a similar fashion. Note that for each electron that flows out of the battery, an ion must flow in the opposite direction inside it.
[/QUOTE]
Not very efficient of course, but doesn’t this one beat it by about 2000 years?
I heard when it was discovered, museum curators around the world panicked. They had assumed the artifacts in their collection were solid gold because they didn’t think electroplating was possible in the ancient world.
[QUOTE=beowulff]
Car batteries are a whole other issue. The CCA is a rating which measures how much current the battery can provide to a load in cold weather. But, since the battery is only 12v, that load must be a very low resistance. So, a 500CCA 12v battery would need a load of no more than .024Ω to actually provide 500 Amps. This is why the cables running to the starter are so thick. This also explains why a 12v battery is safe to touch - your body resistance is much, much higher, so only a very small current will flow.
[/QUOTE]
(underlining mine)
I’m always skeptical of claims where money is at stake. In this case, they’re selling me CCAs—I need them for when I am trying to start the car in the winter, home visiting family. The POS battery that was, of course, standard with the car was pretty weak and I wanted to upgrade.
IIRC the battery weighs 30 lbs. Why don’t they advertise it as weighing 5 lbs (fine print: on the moon)? And as I alluded to earlier, my car stereo claims 270 watts of power, but that’s at 4 ohms…my home stereo uses speakers rated at 8 ohms, and at far less wattage it seems a lot louder. I.e. interpreting the numbers is tricky.
So I read the underlined part and my first reaction was, “So did I get ripped off? Does it provide 500 CCA or can it provide 500 CCA under only optimal circumstances?”
If I’ve worked this out correctly in my mind, I guess the ratings are based on industry standards…they assume a particular resistance and keep the other variables constant so that consumers can make a useful comparison. They’re not selling me a “5 lb battery.”
Suppose you hooked up heftier cables to the battery to reduce resistance…would the CCAs go even higher (assuming you haven’t reached a point of hopelessly diminishing returns)? I guess if you did that, you’d run the risk of frying other components of the system that weren’t designed to handle more CCAs.
If the resistance in the cables is higher than it’s supposed to be, I’m not getting the 500 CCAs promised, but that’s not the fault of the battery manufacturer. Right?
[QUOTE=lobotomyboy63]
They had assumed the artifacts in their collection were solid gold because they didn’t think electroplating was possible in the ancient world.
[/QUOTE]
:dubious: Wouldn’t the density be a bit of a clue? Archimedes, and all that.
[QUOTE=Santo Rugger]
:dubious: Wouldn’t the density be a bit of a clue? Archimedes, and all that.
[/QUOTE]
I don’t know. Can you electroplate lead? Pb and Au, both heavy.
Or maybe they fell down on their scientific approach, starting with the faulty assumption that it was solid gold and working the numbers backward to arrive at some erroneous conclusions.
Gold is about 1.7 times heavier than lead. Silver, what the Wiki claims they electroplated, is 1.8 times lighter than gold. I can’t imagine so many archaeologists (that’s who’d be doing the cataloging, right?) messing up *that * badly.
Sorry for the hijack.
[QUOTE=Santo Rugger]
CookingWithGas, how is the water analogy flawed at the level of detail we’re using in this thread?
[/QUOTE]
At the level of “voltage is like water pressure, current is like rate of water flow, and resistance is increased by narrower or longer tubes” then we’re fine. Start talking about static vs. current flow, how batteries work, etc., then I think it doesn’t do so well.
[QUOTE=GusNSpot]
Always remember and never forget that over 90% of the resistance to electrical flow of the human body is in the skin.
The path, the path, the path. A 6 volt car battery can kill you dead real easy if you poke a finger on each hand so that blood comes to the surface. If those points are put on the + & - post of the battery, you will more than likely almost for sure die… Blood conducts electricity like a mofo… Don’t see many electricians wearing their wedding rings either. Gold and sliver conducts electrons quite nicely also…
Also always unhook the negative post of a battery first and connect it last… Saves on sparks, melted tools and burns…
[/QUOTE]
Seems unlikely: http://www.everything2.org/e2node/death%2520by%2520multimeter
[QUOTE=lobotomyboy63]
(underlining mine)
I’m always skeptical of claims where money is at stake. In this case, they’re selling me CCAs—I need them for when I am trying to start the car in the winter, home visiting family. The POS battery that was, of course, standard with the car was pretty weak and I wanted to upgrade.
IIRC the battery weighs 30 lbs. Why don’t they advertise it as weighing 5 lbs (fine print: on the moon)? And as I alluded to earlier, my car stereo claims 270 watts of power, but that’s at 4 ohms…my home stereo uses speakers rated at 8 ohms, and at far less wattage it seems a lot louder. I.e. interpreting the numbers is tricky.
So I read the underlined part and my first reaction was, “So did I get ripped off? Does it provide 500 CCA or can it provide 500 CCA under only optimal circumstances?”
If I’ve worked this out correctly in my mind, I guess the ratings are based on industry standards…they assume a particular resistance and keep the other variables constant so that consumers can make a useful comparison. They’re not selling me a “5 lb battery.”
Suppose you hooked up heftier cables to the battery to reduce resistance…would the CCAs go even higher (assuming you haven’t reached a point of hopelessly diminishing returns)? I guess if you did that, you’d run the risk of frying other components of the system that weren’t designed to handle more CCAs.
If the resistance in the cables is higher than it’s supposed to be, I’m not getting the 500 CCAs promised, but that’s not the fault of the battery manufacturer. Right?
[/QUOTE]
CCA is just a measure of “goodness.” It doesn’t say anything about whether it will start your car! Presumably the FTC would come after the manufacturer if they were selling truly substandard batteries, and they got enough complaints. Same thing about Amp power - there are specific conditions (load, amount of clipping allowed, distortion, etc.) at which the maximum power is measured. Note that none of these conditions say “using lobotomyboy63’s speakers.” Your home speakers may be much more efficient than your car speakers, so they may sound louder for a given power.
I do tend to agree that there is often fudging going on with ratings. I’m a bit of a flashlight freak, and I’m always looking for the next brightest LED flashlight. If you look on ebay, you can find the same flashlight being rated at 5W and 8W. It’s pretty clear to me that they are the same, and the seller is fluffing up the rating to attract non-critical thinkers. It can be hard to verify ratings as a consumer - Caveat emptor!
[QUOTE=beowulff]
Seems unlikely: http://www.everything2.org/e2node/death%2520by%2520multimeter
[/QUOTE]
I really really hope you never bet your life on this article.
Humm ‘kilo’ and ‘mego’… (averages huh?)
Absolute minimum to kill, not guaranteed to kill.
9 volt multimeter battery can provide xx amps..
6 volt auto battery can provide xxxxxxxxx amps. Plus are hard to find now, wanna try a 12 volt one?
Electricity needs great respect and caution.
[QUOTE=GusNSpot]
I really really hope you never bet your life on this article.
Humm ‘kilo’ and ‘mego’… (averages huh?)
Absolute minimum to kill, not guaranteed to kill.
9 volt multimeter battery can provide xx amps..
6 volt auto battery can provide xxxxxxxxx amps. Plus are hard to find now, wanna try a 12 volt one?
Electricity needs great respect and caution.
[/QUOTE]
We’ve been over and over this.
A 12v battery that fits in your car alarm key fob can provide just as much current into a 1kΩ load as a 30 lb car battery! If you don’t understand that the load resistance is what determines the amount of current, then you need to go back and do your homework.
It would be exceedingly unlikely that you could be killed by a 12v battery, even if you had direct blood contact. I’m not going to say it’s flat out impossible, just very, very unlikely. In the entire history of the Automobile, I’ve never heard of this happening. Have you?
[QUOTE=CookingWithGas]
At the level of “voltage is like water pressure, current is like rate of water flow, and resistance is increased by narrower or longer tubes” then we’re fine. Start talking about static vs. current flow, how batteries work, etc., then I think it doesn’t do so well.
[/QUOTE]
Actually, static electricity (in the sense of getting a shock after walking across the carpet) is modeled well by a water tank that is very high, but very, very skinny. There’s a lot of pressure at the bottom, so if you make a connection, there’s a lot of flow for the first fraction of a second, but there’s not much water in the tank, so it’s all gone almost immediately, and the flow stops.
[QUOTE=lobotomyboy63]
@Crafter: what are the ions? I remember ions from Chem but what do you mean? These must be ions in the metal contacts to the battery?
@QED: OK, it makes sense that the flow is from negative (it’s an electron) to positive.
So AC provides a return path of sorts (some positive, some negative but otherwise like DC)?
PS to other posters: I can pretty much track on the sine wave stuff, having studied trig in high school.
[/QUOTE]
In case this wasn’t answered:
In a nutshell, an ion is just an atom or molecule that has either gained or lost one or more of its valence band electrons, giving the resulting atom or molecule either a positive charge (if it lost enough electron/s) or a negative charge (if it gained enough electron/s).
[QUOTE=ExTank]
In case this wasn’t answered:
In a nutshell, an ion is just an atom or molecule that has either gained or lost one or more of its valence band electrons, giving the resulting atom or molecule either a positive charge (if it lost enough electron/s) or a negative charge (if it gained enough electron/s).
[/QUOTE]
OK, that matches the definition from chemistry.
When I imagine electricity, I think of a battery connected to a light. Electrons leave one end, go to the light, and exit the other end, then return to the battery.
When someone posted “ion,” it’s made me imagine entire atoms traveling across the wire, not bare electrons. Or, is this to say that really, as the electrons travel through the wire, their charge makes the copper in that wire into ions by upsetting their natural charge—and then they revert to non-ions when the power is turned off?
[QUOTE=lobotomyboy63]
OK, that matches the definition from chemistry.
When I imagine electricity, I think of a battery connected to a light. Electrons leave one end, go to the light, and exit the other end, then return to the battery.
When someone posted “ion,” it’s made me imagine entire atoms traveling across the wire, not bare electrons. Or, is this to say that really, as the electrons travel through the wire, their charge makes the copper in that wire into ions by upsetting their natural charge—and then they revert to non-ions when the power is turned off?
[/QUOTE]
The ions only come into play inside the battery. In a wire, you have a solid consisting of countless copper atoms. These atoms have loosely bound outer electrons. It doesn’t take much energy to “bump” and electron from one atom to the next, so you can think of the current as slowly bumping electrons (like BBs being poured down a pachinko machine). An individual copper atom may become ionized for a brief time, but it’s not significant.
Semiconductors are also interesting - depending on the doping, the current may be carried by excess electrons or by the lack of electrons (holes). But, that opens up a another topic…
[QUOTE=beowulff]
The ions only come into play inside the battery. In a wire, you have a solid consisting of countless copper atoms. These atoms have loosely bound outer electrons. It doesn’t take much energy to “bump” and electron from one atom to the next, so you can think of the current as slowly bumping electrons (like BBs being poured down a pachinko machine). An individual copper atom may become ionized for a brief time, but it’s not significant.
[/QUOTE]
Ah, I see. The quote was about electrons moving inside the battery, not inside the circuit. My bad. :smack: Makes sense: acids in the battery are formed with ionic bonds.
[QUOTE=CookingWithGas]
This comes up every time in a discussion like this, where someone eventually says, “It’s not the volts that kill you, it’s the amps.”
[/QUOTE]
We should note that there are multiple ways in which electricity can kill a person.
[ul]
[li]Disruption of the heart’s electrical system. This takes only a tiny amount of electricity, if it has a direct path to the heart. Even if it has to travel through the arms & chest, it’s still only a small amount. The coin-cell battery inside a wristwatch is way more than needed (similar batteries power a heart pacemaker for years). But there are lots of variables related to skin resistance, AC vs. DC, frequency, etc. And in some people, their heart just restarts and goes back into a normal rhythm even after such a shock, so they survive.[/li][li]Damage to the nerves of the heart or lungs. This is most common from repeated, non-fatal shocks. They cause neurological damage, which eventually causes these nerves to these vital organs to fail, which then causes death. [/li][li]Heat damage to vital organs, such as the brain or heart. Examples of this would be electric-chair electrocutions, where the current passes from the metal skullcap through the brain, the heart & lungs, to the metal plates on the legs. There is a much larger amount of electricity involved here, as indicated by the stories of bodies being burned or starting on fire during electrocutions. And the current is applied for much longer, compared to accidental electrical shocks. [/li][li]Heat & physical shock damage to the body. This is typical of industrial accidents, or someone touching a high-voltage wire. These are sometimes referred to as ‘electrical explosions’, where the shock wave can actually break bones, along with body injury from the heat of the blast. These, too require much larger amounts of electricity.[/li][/ul]