Why Your Battery Percentage LIES To You

Your phone drops from one hundred to ninety in minutes, then sits at thirty forever. Your battery meter is guessing.

Why does the battery percentage fall unevenly, fast at the top, stuck in the middle, then a sudden plunge?

Your phone cannot directly see how much charge is left. It mostly infers it from the battery's voltage. But a lithium battery's voltage does not fall in a straight line. It drops a bit at the start, then flattens into a long plateau where it barely moves across most of the usable charge, and finally falls off a cliff near empty. So in that flat middle, a tiny voltage change hides a huge chunk of real capacity, and the phone's guess can lag or jump.

So the percentage is not a fuel gauge, it is an educated guess translated from a curve that lies flat in the middle. That is also why charging from twenty to eighty is genuinely gentler: you skip the stressful voltage extremes at both ends.

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