?

Log in

No account? Create an account

Previous Entry | Next Entry

What the F#@%

Why is it there are so many different sizes of batteries for home electronics and flashlights and things? Given the fact that AAA, AA, C and D size batteries are all 1.5 volt, why do we need all those sizes? Couldn’t there just be one size of 1.5 volt battery and all the electronic manufacturers could make their products conform to that battery size? And what ever happened to A and B size batteries anyway? And why does a 9 volt battery measure about 2 inches long but a 6 volt battery is bigger than your fist and weighs a pound or more? Does this make sense to anyone? Why even have 6 volt batteries if they are going to be that big? We can make a 9 volt small, why not a 6 volt?

And what is up with car batteries being different sizes? I know the battery placement is an issue when they design a vehicle but wouldn’t it be more efficient to just make vehicle batteries in fewer sizes rather than a separate configuration for each vehicle? In my perfect world there would be three kinds of consumer vehicle batteries. Car batteries – just one size fits all. Pickup truck/Van/SUV batteries – again one size fits all and no side post batteries damnit. RV/Boat batteries – just one size here too. Let the manufacturers design around the size and shape. That way when your battery gets old and you have to replace it, you just walk into the store and say, “I need a battery.” The clerk asks, “For what application?” and you would say “I have a car or a truck or a van or a boat or a gas hogging SUV or an RV.” And the clerk sells you the appropriate battery. No more asking what year, model, engine size, transmission configuration, fuel type and everything else they feel the need to ask you now.

Is this too much to ask?

Wander

Comments

( 10 comments — Leave a comment )
gnominclature
Jan. 20th, 2007 02:34 am (UTC)
I say this everyday :(
wander
Jan. 21st, 2007 01:11 am (UTC)
You know it's part of the conspiracy between the auto industry and the auto parts industry don't you?

W
gnominclature
Jan. 23rd, 2007 06:04 pm (UTC)
Oh yes. Many things are!
redsgoddes
Jan. 20th, 2007 04:34 am (UTC)
"Is this too much to ask?"</>

Yes
brotherskeeper1
Jan. 20th, 2007 07:28 am (UTC)
Ditto. I hate flashlight batteries being big and fat or medium and fat of small and fat. I have a great disdain between AA and AAA as recorders and most devices use the AAA but my glucose monitor, of course has to be different take the itty bitty AA size. Grrr!
(Deleted comment)
wander
Jan. 21st, 2007 01:08 am (UTC)
As far as I can see, a 12V battery is the same across the board. I think they are in different configurations so car manufacturers can get away with selling more parts.

You know I put these things out there just for you don't you? You missed one I posted back before Christmas. I even made a pointed comment about you in the post.

W
dragoneerl
Jan. 21st, 2007 12:33 am (UTC)
EDIT: Corrected and reposted.

I am by no means a battery afficionado, but I think I might have an explanation regarding your battery-size issue:

The size of a battery has little to do with its potential (or Voltage, if you prefer), as you have no doubt guessed. Without getting too deeply into the chemistry and physics of batteries, here's what's going on:

A battery works because of oxidation-reduction reactions (or redox reactions for short). In a redox reaction, electrons from one reactant (the reducing agent) are transferred to another reactant (the oxidizing agent). In a spontaneously-occuring redox reaction, the electrons exist in a higher energy state inside the reducing agent (hereafter, RA) than they do when they are accepted by the oxidizing agent (OA). This means that the electrons must lose energy as they travel.

If you perform a simple redox reaction in a beaker, such as, say, dissolving a piece of aluminum foil in lye, that energy will be shed as heat; the beaker will become quite warm. What if, however, you could harness that shed energy to do useful work, like running a flashlight or a radio?

Turns out you can, but you have to be a little bit sneaky about it. The oxidation and reduction that make up a redox reaction must occur simultaneously, but they need not necessarily occur in the same place. You can put the RA in one compartment and the OA in another compartment, then connect the two compartments with a wire. The electrons lost by the RA will then travel through the only available pathway, the wire, to get to the OA. Anything connected to the wire, such as a light bulb, can then make use of the energy lost by the electrons as they travel. Pretty clever, huh?

So that's what a battery is: the reactants necessary for a redox reaction, separated into two compartments, waiting for a closed circuit to allow electrons to flow from the RA (which corresponds to the negative terminal of the battery, called the anode) to the OA (the positive terminal, or cathode). So what exactly is Voltage?

Voltage is a measure of the electric potential difference between the poles of a battery. The greater the Voltage, the more energy an electron loses as it runs from pole to pole. This is determined by two major factors: the nature of the reactants used in the battery, and their concentrations. By changing how concentrated one or both reactants are, or by changing the reactants, you can affect how much of a potential drop there is between the anode and the cathode. And, of course, by changing the potential drop (or Voltage), you change how much energy is available to run whatever is hooked up to the battery.

I should point out here that I've intentionally made a small (but common) error in terminology. The device described above is more properly known as an electrochemical cell or a galvanic cell. A true battery is actually a collection of cells wired in series to increase the overall voltage. A 9-V battery, for example, actually contains six small 1.5-V cells wired in series. The anode of the 9-V battery connects directly to the anode of the first cell, while the cathode connects directly to the cathode of the last cell. Your typical car battery (12 V) is a collection of six 2-V lead-acid cells.

The size of the battery (or cell) has more to do with how long the cell lasts than the voltage it produces. As you correctly pointed out, AA, AAA, C, and D cells all produce 1.5 V (when new) but you can expect a AA cell to last longer than a AAA cell, and you can expect C and D cells to last even longer. It's not too hard to see why: larger batteries hold more reactants.

So a big honkin' heavy duty 6-V battery will typically last longer than a much smaller 9-V battery, which is a quality you want in your emergency flashlight.

As for the whole different-size car-boat-truck-RV battery issue...I'm afraid I don't have an answer for that. The cynic in me thinks that there is no major difference in the battery types, and that they just ask you a bunch of questions so they look expertish before going back into the stock room and pulling a battery off the shelf that's identical to the one million others sitting up there. But that's probably not right.
ryl
Jan. 21st, 2007 05:20 pm (UTC)
But that's probably not right.

That probably is right and the Vast Auto Parts Conspiracy is probably going to have you killed for figuring it out.

It was nice knowing you. Sorry it had to end over a battery.
celestialmarvel
Jan. 26th, 2007 05:11 am (UTC)
Sure I'll add you to my journal, always welcome new people. Welcome! Add me back?
wander
Jan. 26th, 2007 06:42 am (UTC)
yup, I will.

W
( 10 comments — Leave a comment )