We touched on how battery performance gradually degrades in our earlier post, as a previously charged battery goes flat. But it will never quite be the same again, because of chemical processes occurring inside the case. We turn our attention now to battery memory effect, and self-discharge as two major related phenomena.
Limiting Factors of Battery Memory Effect
Battery memory effect encompasses the fact that batteries neither completely discharge, nor fully recharge either. They also remember where they were in the range the previous time, and tend to go back to that point in future. Some batteries are also open to user intervention, whereby they take over our bad habits.
In some battery chemistry, this phenomenon is due to the active metal and electrolyte forming a salt during discharging. And then dissolving this when recharging according to Australian Academy of Science. This may leave uneven crystals on the surface, affecting the way the battery behaves in future.
Factors such as temperature, charge voltage, and charging current may also have a bearing on how the crystals form. However, the fact of the matter is the battery departs from its original design. But we may be able to influence this by the way we treat the battery when it is new.
How Batteries Tend to Self-Discharge
The chemistry that enables some batteries to recharge, has an unfortunate side-effect. And this disadvantage is they have a greater potential to discharge themselves too. This happens when:
- Internal reactions occur inside the battery case when not connected to an external circuit.
- These phenomena lead to a loss in chemical energy. The battery may even eventually go flat.
Lithium-ion batteries in phones may self-discharge by 2% to 3% a month. Lead-acid batteries can shed as much as 6% of their energy monthly. While nickel-based ones may lose as much as 15% of their power during that period. Interestingly enough, a non-rechargeable alkaline battery may only lose around 2% to 3% per cent per year.
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