Why YSK:
The number you see (e.g., 37%) is an estimate calculated by the phone's battery-management system. It isn't simply measuring "37% of the battery's stored electricity."
Battery voltage, temperature, charging history, battery age, and how much power the phone is currently using all affect that estimate.
That's why:
- A phone can sometimes stay at 1% for surprisingly long.
- Battery percentage can drop faster during gaming or other intensive tasks.
- An old battery may appear to drain much faster than a new one.
- The percentage can change noticeably after restarting the phone.
- 50% battery doesn't necessarily mean you have exactly twice the usable runtime of 25%.
Also, lithium-ion batteries generally age faster when they're repeatedly kept at very high or very low charge levels. Modern phones manage this automatically, but features such as optimized/adaptive charging can further reduce battery wear.
So the battery percentage is best thought of as a calibrated prediction of remaining usable capacity, not a literal fuel gauge.
Your phone isn't lying to you—it just has to estimate something it can't directly measure.