An Electrical Engineer's Notes: A Simplified Explanation of Batteries

Hey All,

Have you ever wondered how a battery works or how your car's presence is sensed at a traffic light? What about how an incandescent light bulb uses electricity to “generate” light? As I dive deeper into my studies, I will present you with simplified explanations of how modern day electronics work. The more I learn, the more I can share. Let's begin with batteries...

SO how does a battery work? Well it's obvious right? The battery has stored electricity and when you put your battery into a gadget, all the power flows from the battery into your device. Simple enough...

Wrong. Actually, nothing leaves the battery. How can this be? Something has to get electricity moving and if it's not the battery what is it?

The answer is... the battery! Let me explain.

Are you familiar with potential energy in physics? Voltage, is essentially potential energy for electricity. The presence of voltage, leads the way to electric current (which is the movement of electrons). Lets say you have your cell phone without a battery, just sitting on the table in front of you. The voltage and current inside your phone, is pretty close to zero, which is why it doesn't turn on.

When you put in the battery and turn on your phone, suddenly the battery is creating a voltage drop. A voltage drop is a change in the voltage across a given part of a circuit. So where the voltage all across the phone was zero, suddenly the presence of the battery has changed the voltage. When this happens, you get a voltage drop and that is what, “jump starts” the electrons (the ones that help make up all the wires and chips) into movement and you have current moving through the rest of the phone!

Yes, the electrons that help make up the actual circuit elements, “become” electrical current when they start moving. Thanks to the battery disrupting the “peaceful” state of the phone, you get electricity on the go.

How does the battery die then? A battery is “discharged” when it loses the ability to keep creating that voltage drop. When that happens, the electrons stop moving and the phone turns off.

On an extra note, the Positive (+) and Negative (-) ends of a battery can be misleading. Electrons move from (+) to (-) so positive charges really indicate the absence of electrons. Electrons do move through the battery but remember that they are from the rest of the circuit and not usually the battery itself.

Obviously this is just a simple explanation of how many everyday batteries work, and there's a little more too it, but it is the general concept and the basis of their functionality.

Until next time,

- EE

Tags: batteries, cell, electrical, engineering, phone

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Comment by EEngineer on April 25, 2009 at 7:52pm: @Dan: I did think about that route as I wrote this post however to keep things simple, I decided to stick with the electrical aspect of it. I may cover that in a later post.

Comment by Dan on April 25, 2009 at 10:26am: This is all well and good, but way over the average laymans head. However, being that you have gone thiis route, you should go one step further and use pictures, tell us about the chemical actions inside a battery. How one time use batteries are different then rechargeable batteries. One other tech note here, I wonder if many people are aware the the earths "ground" is actually positive and the clouds/atmosphere is negative?
Dan

Comment by EEngineer on April 24, 2009 at 11:33pm: For those inquiring more, I used the passive sign convention in my analysis of the battery.

Comment by kinglacho on April 24, 2009 at 10:03pm: Dear @E-Engineer, your article is obviously going to simplify the concept for everyone to understand. Congratulations! Now, I just wanted to clarify something you've said both in the blog post as well as in one of your comments: you mention that there are 2 types of current, Conventional and Electron. I just wanted to clarify something which I think may get some folks out there a bit confused.

The motion of electrons that makes what we all know as current, happens due to the fact that electrons move from the areas with less potential energy, to the areas with more potential energy. If you want to look at it from the polarity point of view, they move from (-) to (+). What you name "Conventional Current", which is understood as the direction of the current going from (+) to (-) is due to an actual Convention that was introduced by Ben Franklin, which is called the "Franklin Convention". This, of course, having to do with his studies on electrostatic fields. When studying Electronics and Electricity, we commonly use the Franklin Convention in order to simplify things and therefore, get a better understanding about these things. In physical reality, we find out that all electrons move from (-) to (+).

Anyways, just wanted to bring some light on to that particular subject, and by the way, it's always nice to find future colleagues on the Web, who are so willing to share their knowledge with other people. Cheers! xD

Comment by SteamyWeenie on April 24, 2009 at 2:11pm: bump

Comment by EEngineer on April 24, 2009 at 12:40pm: @Zagorath: These concepts aren't beyond you. You were the only one to pick up the fact I didn't mention conventional current. :^)

Comment by Amit Dahan on April 24, 2009 at 8:59am: I like your blog posts, they're long, interesting, and educating!

Comment by Zagorath on April 24, 2009 at 8:52am: I'm afraid that this is beyond me...
Oh well :D

Comment by Ather on April 24, 2009 at 8:11am: @Bren also making sure the contacts are clean

Comment by EEngineer on April 24, 2009 at 8:08am: @Bren:

There's not much that can be done to prevent a battery from losing it's ability to function over time. The good news is, the decay in performance can be slowed by keeping it in ideal conditions (low humidity and room temperature).