Batteries: Why no method of charging is fantastic, even when fantastically methodical


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Aug 1, 2010
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Li-Ion batteries last long (in charge and life), they have no "memory effect" (more on this later), and have a high energy density. But, they are innately just as gimped as other batteries, and any method of charging them is always a double-edged sword.

Stand back, I'm going to try science.

Basically, a battery works when chemical reactions "pull" electrons to one side (the side with the most potential energy). Since energy is again used to pull it back after going 'round the circuit, and there is always an external force acting upon the particles in battery (resistance, mostly in the form of chemical deposits that slow down ion transfer), the reaction will never occur with the same amount of energy each time - it will always be slightly less. (Which means it will always "pull" less, meaning less charge to go around the circuit.)

On the other hand, Li-ion batteries actually have a longer life if you recharge them a lot. This completely contradicts the above statement, but it's true. Despite losing a tiny fragment of maximum charge after each recharge, letting your Li-ion battery run to it's minimum is MUY MAL (due to chemical decomposition [having to go through a full recharge means longer and more chemical reactions]).

So: recharging a lot inherently decreases maximum charge, and not recharging a lot inherently decreases battery life. If you want your battery to last a long time, recharge it frequently. If you want it to last less time but hold a long charge, recharge it less frequently.


It's physics, so naturally it's going to be disappointing in real-world scenarios. :cool:

(Also: if for some crazy reason you're going to leave your phone off for a long period of time, completely discharge it* first. Another contradiction to prolonging battery life, but if you don't oxidation will drastically increase resistance levels and decrease the battery life.)

*It's impossible to completely discharge a Li-ion battery (in a phone). The manufactures engineer the device to turn off if the charge reaches dangerously close to 2.5 millivolts per cell, because if the charge goes between 1.5 and 2.5 millivolts per cell the battery will not charge again with a home charger (you have to get the manufacturer to use their "mondo" chargers to get it back up again.) If it falls below 1.5 millivolts per cell, then it is permanently and irreversibly dead. (If you have a percentage battery monitor it might say "0%" before it shuts down, but it is lying to you. That's because they want to keep you blissfully ignorant to the tiny bit of charge on the battery to avoid confusion when your phone turns off but you "still have power." Which in itself is another reason why phones don't come stock with super-accurate percentage- and voltage-based battery monitors.) So, it was ultimately futile when people were conditioning their Li-ion battery's memory effect. Doing so would require a full power drain, which is impossible.
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