If I leave a fully charged battery in a drawer and never touch it, why does it slowly lose power over time? Nothing is plugged into it, it’s not powering anything… so where’s the energy going?
If I leave a fully charged battery in a drawer and never touch it, why does it slowly lose power over time? Nothing is plugged into it, it’s not powering anything… so where’s the energy going?
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batteries work like moving stuff (ions iirc) from one side to the other side. Thats the charging and discharging.
So with time (due to physics and chemisty) the particles move slowly from one side to the other to create an equilibrium of sorts. Thats why they never fully discharge but go to around 50ish%.
Thats why most batteries get delivered at around that charge (if its rechargeable ones)
Batteries use chemical reactions that cause an excess of electrons in one electrode and a lack of electrons in another. This imbalance causes the reactions to stall out – almost. But there are still ways in which they can proceed, only very slowly, and there are unavoidable side reactions that either screw up the imbalance or drain the energy from the active chemicals in unwanted ways. Different battery chemistries respond differently, for instance a lead-acid battery will have more unwanted reactions the lower its state of charge is, while a lithium-ion battery will have most of them if it’s fully charged or fully drained. Lithium non-rechargeable batteries have the best longevity, frequently lasting more than 10 years in low drain situations.
Batteries have a voltage, which is a “potential difference” from the separation of negatively and positively charged ions and electrons. Over time, internal chemical reactions slowly undo that charge separation. It’s called self-discharge and uses up the energy inside the battery, even if it’s not powering anything. The causes of self-discharge can vary, and usually just stems down to the fact that no battery is perfectly sealed or built. Some imperfection essentially allows electrons to move ever so slightly even when there’s no external circuit, wasting energy internally. Temperature also largely determines the rate of self-discharge. Warmer temperatures speed up chemical reactions, degrading the battery faster.