Why Your Phone Slows Down

It happens like clockwork. A new phone model is announced, you install the latest software update, and suddenly your perfectly capable device feels… sluggish. Apps stutter. The keyboard lags. The conspiracy theory writes itself.

Is it "planned obsolescence"? Is the manufacturer slowing you down to force an upgrade? The answer is legally complicated, but engineered simply: It's about voltage, not speed.

The CPU Demand

Your phone's processor (CPU) is a thirsty beast. When you tap the shutter button to take a photo or launch a 3D game, the CPU goes from idle to 100% performance in milliseconds. This creates a massive, instantaneous demand for power.

A healthy, new battery acts like a wide pipe. It can deliver that rush of current without breaking a sweat. The voltage stays high (e.g., 3.8V), and the phone works perfectly.

Internal Resistance: The Clog

As batteries age, their chemicals degrade, leading to an increase in Internal Resistance. This is like clogging the pipe with gunk.

Now, when the CPU demands that massive spike of power for a photo, the battery can't deliver the current fast enough through the resistance. Ohm's Law takes over:

Because resistance is high, the voltage drops (sags) significantly. If the voltage drops below the critical operating threshold of the components (usually around 3.0V - 3.4V), the phone will instantly black out and restart to protect the electronics.

The "Solution": Performance Throttling

Phone manufacturers faced a choice:

1. Let old phones crash and restart randomly when doing heavy tasks.
2. Artificially limit the CPU speed so it never demands more power than the weak battery can give.

They chose option 2. By capping the CPU speed (throttling), they ensure the current spike never gets high enough to cause a dangerous voltage sag. Your phone doesn't crash, but it feels slower because the brain is running at half speed.

Can you fix it?

Yes. The silicon in your phone (CPU, RAM) does not degrade meaningfully over 2-3 years. It is perfectly capable of running fast. It is only the power delivery system that is failing.

Replacing the battery removes the high resistance. The throttling software detects the healthy voltage curve and automatically uncaps the CPU performance. Your 3-year-old phone can literally become as fast as the day you bought it for the price of a battery swap.

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