I just went out to buy some 9 Volt batteries because the fire alarm decided to be my alarm clock today and tell me, quite loudly, it was hungry and needed more batteries (/s). I replaced the battery and went to go pick up some more batteries for when the other fire alarms require replacement batteries, and I had thought, if those batteries stay in the package for an extended amount of time, will they still have the same amount of life in them as when i first bought them? Or will they lose power and life, even though they are sitting in a sealed package?
In: Technology
Batteries slowly die even when in their package. I don’t feel qualifies enough to explain why but I think it has sth to do with their internal resistance.
Lithium batteries contain a solution inside of them that changes form to release energy. Essentially when the battery is discharging the solution inside of them transforms into another state that releases electrons and creates power, and unlike single use batteries this solution can be returned to it’s original form when you recharge it. You can think of it like a spring. When your using it it slowly spreads out and loses energy, and by charging it you compress it again. Unfortunately this process isn’t perfectly efficient and it’s thought that this solution can also react with the casing around the battery and turn it into a type of salt. The more times you use the battery (cycles of charging and discharging) the more of this solution turns into this salt and the less is left to store energy.
I have lots of rechargeable AA and AAA, very handy for smoke detectors, flashlights, remote controls etc. I never need to run to the store to get a battery. Better for the environment too. I have had a couple wear out but it took years. In the meantime, I would have used dozens and spent a lot of money.
All batteries have some degree of self discharge. How fast they self discharge depends on the battery chemistry; nickel chemistries have a very high self discharge, while alkaline are very slow, which makes them stable on the shelf.
I don’t really know the details of how self discharge works. It’s down to the chemistry itself, the charges want to balance out, and there’s a very high resistance path between cathode and anode that electrons slowly leak across.
Inside a battery is an “electrolyte” basically a goo that electrons can flow through but need a push to want to flow. The electrolyte separates 2 elements that want to share electrons. When they share, the element becomes a slightly different element, but the important part here is that the element with shared electron no longer will accept another electron. When you connect both ends of the battery electron flows from negative to positive outside the battery, but positive to negative inside the battery, pushing its way through the goo. The battery is “dead” when it no longer has enough unused elements on each side of the goo center. Now using a battery will make electrons flow through the goo and use up the elements. But sitting on a shelf, the electrons very slowly push their way through the goo. So if left to sit for a very long time it would eventually use up all the elements and not be able to produce power anymore.
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