BATTERY CAPACITY LOSS – WHY DOES MY BATTERY LAST ONLY 10 MINUTES?

Laptop batteries consist of two main components: an electronic control board and a set of cells. The electronic circuitry is responsible for charging and discharging the battery, and it communicates with the laptop through the SMBus interface. Through this communication channel, the laptop receives all necessary data — such as temperature, voltage, remaining capacity, and safety parameters. Based on this information, the laptop either accepts the battery as fully functional or rejects it entirely.

The second component of every battery is the set of cells, usually lithium-ion. These cells store energy and provide power to the laptop. Their most important parameters are: – nominal voltage – capacity – internal resistance The last element — internal resistance — is key in understanding why battery capacity decreases with age.

(Lithium-ion cells with an electronic control board inside a laptop battery)

Brand-new lithium-ion cells have very low internal resistance. This means the voltage drops slowly during normal use, from a full charge (4.2 V per cell) down to the emergency low-voltage point (around 3.4 V). When the voltage reaches this threshold, the battery’s controller signals the laptop that the battery is nearly discharged.

As the battery ages, the internal resistance of the cells increases. Even if the battery is fully charged, the voltage may drop immediately under load, triggering a premature “low battery” warning. This is why an old battery may drop from 100% to 5% in seconds and shut down shortly after.

The increase in internal resistance is a natural chemical process — it happens in all lithium-ion cells regardless of the manufacturer or the laptop brand. Unfortunately, there is no method to reverse this process. In other words: nothing can stop a battery from aging. Proper maintenance may slow degradation slightly, but no technique can restore a worn-out cell to its original condition.

(Lithium-ion cells arranged in parallel pairs inside a battery pack)