What ultimately causes batteries to completely die?


Some batteries that sit in unused electronics for an extended amount of time don’t hold charges anymore.

So is it better to periodically charge electronics that aren’t used regularly just to keep the battery from losing its useable life? Or is it reasonably just a matter of time before batteries aren’t reasonably usable?

In: Technology

most electronics these days draw a very small amount of current to keep standby power running for things like built in clocks, wifi or GPS if they are enabled. Batteries will also self discharge if the casing of the battery is dirty which will cause a small amount of current to flow from the negative terminal to the positive terminal. Chemical reactions inside the battery will also cause them to self-discharge.

Batteries are basically a little block of material rusting in order to make electrons move. One that little block of material rusts completely, or at least enough that no more if it can rust, it can’t make electrons move anymore. As long as there is any connection between the two ends of the battery, even a bit through the inside of the battery, it’s rusting in order to make electrons move along the connection.

Rechargable batteries are different because we can reverse the flow of electrical to reverse the rusting, restoring some of the material to it’s original condition. This always it to rust again in the future to supply electricity. But the reversing process isn’t perfect, so the amount of material that gets restored decreases with each charging cycle, if only a little bit. If the amount of material available gets small enough it won’t be able to push as many electrons as hard as it used to when it rusts, and possibly not enough or hard enough to make the device it’s attached to run anymore.

The answer to your question varies. There are just a bunch of types of batteries. The chemical reaction that is used in liquid-filled batteries (like used to be in car batteries) is one of the oldest chemical reactions known to man. **Understanding this one is the easiest way to understand all the others.**

In this reaction there are two pieces of metal. The important thing is they’re not the same kind of metal. The metal pieces both hang in a tub of acid (or alkaline, depends on the battery). **The metal is being slowly dissolved by the battery.** As this happens, little hunks of metal float over to the other piece of metal. They get stuck. This is called electroplating. This is how ancient smiths plated things. We’ve been doing this for as long as we’ve been making things of metal.

Humans figured out that if you touched the other piece of metal – the one being covered – you got a brief shock. We eventually figured out stuff we could do with that shock. That led to ways we tried to get a more consistent shock instead of a burst of shock. Now we have tons of types of batteries, with a bunch of different ways they all do essentially the same thing.

The universe likes balance.

The trouble with balance is if things are balanced, there’s no energy to move stuff around, because everything is pretty much happy where it is.

Batteries are little boxes of extreme imbalance. They are contraptions using chemical trickery to make electrons move.

For each little chemical reaction that sends an electron shooting through your electronic device, the battery loses a little. It becomes more balanced. Eventually the chemical trickery just has no more electrons to give, and the battery dies in a landfill as a little box of useless, but stable metal.