Why do batteries go bad?

[Janx]

Here's a science question that isn't as lofty as going faster than the speed of light or killing your grandpa.

Why do batteries sitting in a device that is allegedly turned off go dead sooner than if we take those batteries out.

in the simplest device, a battery has wires coming from the + side to a light bulb, and from the minus side to a switch which then leads to the other terminal on the light bulb.

leaving the batteries in or out of the device shouldn't affect the longevity of the batteries. When you pick up the flashlight and use it, it should be good as good to go regardless.

Moving on to my xbox controller, that puppy will suck my batteries faster than Keanu Reeves will drain a movie of quality. And that's with the controller OFF.

What the heck is going on? Why is it better to remove the batteries, even in short term (days/weeks)?

 

[jonesy]

I'm guessing it might be temperature. A battery enclosed inside something (a device) might become ever so slightly warmer than one that isn't, and a rise in temperature does cause the chemical process that degrades batteries to happen faster.

 

[Alan Shutko]

The controller is drawing a constant amount of power to monitor the Xbox button to know when it should go active. That shouldn't require too much power but it will add up over time. If the controller had a hard on/off switch that would stop the drain.

 

[sabrinathecat]

Have the same problem when I'm traveling with my iPod. I just charged it. I waited for the display to close down. I locked to off-control. How is it that by the time I reach the airplane the battery is 1/2 dead?

 

[Deset Gled]

Alan hit the nail on the head: "off" is not the same as "unplugged". Some devices use power to monitor for a switch - it's pretty much a guarantee that any device with a push-button on/off switch needs some power to monitor it. Some devices use power to monitor for wireless signals. Some things have indicator LEDs that are always on. And some circuits simply have a small amount of leakage current that you just can't do anything about (often due to power conversion methods).

On a related note, do you know how much electricity you can save by unplugging appliances instead of just turning them off? http://money.howstuffworks.com/personal-finance/budgeting/how-much-save-unplugging-appliances.htm

 

[Janx]

Have the same problem when I'm traveling with my iPod. I just charged it. I waited for the display to close down. I locked to off-control. How is it that by the time I reach the airplane the battery is 1/2 dead?

Alan's nailed the xbox controller mystery.

as to your ipod, it's more probable that you have an older model, and have reached the end of the battery's life.

per the old apple iPhone specs, it lost a minute in life after every full recharge. 2 half-charges would equal one full charge. basically, each time you charge it, it decreases how much charge it can hold. The iPhone battery was rated for about 18 months usage on average, before it degraded to "annoying unuseful"

I would assume any of the Lithium battery systems have a variant of this behavior.

The worst I saw was the official xbox controller rechargeable batteries. i bought a charging kit for each controller (4). But I mainly use one. The others died after a few months of non-use. Meaning, they were dead and would not take a charge anymore. They basically died from lack of use. I use regular batteries now as I'm kinda miffed at wasting $30.

 

[Umbran]

in the simplest device, a battery has wires coming from the + side to a light bulb, and from the minus side to a switch which then leads to the other terminal on the light bulb.

leaving the batteries in or out of the device shouldn't affect the longevity of the batteries. When you pick up the flashlight and use it, it should be good as good to go regardless.

Except...

In, say, a flashlight that's turned on, you have a complete circuit, and current flows.

When you turn it off, the switch breaks the circuit, and the current stops flowing... much. There is still a potential difference (a voltage) across the switch. The resistance across that gap is sky-high, so very little current can flow, but very little is not equal to zero.

 

[dogoftheunderworld]

Nothing to do with battery drainage per se, but also batteries left in a device for a very long time (like a flashlight you only use once a year) can cause corrosion to occur on the battery and the device terminals (which also probably lowers the resistance Umber spoke of).

** I am not a scientist, nor do I play one on TV **

 

[Umbran]

Nothing to do with battery drainage per se, but also batteries left in a device for a very long time (like a flashlight you only use once a year) can cause corrosion to occur on the battery and the device terminals (which also probably lowers the resistance Umber spoke of).

Corrosion typically raises the resistance, but the resistance is already high enough that it isn't a major deal.

 

[Hand of Evil]

Research and Designed - Yep, they are made that way!