Thursday 24 September 2026

Issue 142 · Long reads on work, technology and everyday life

In this issue

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Long reads

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thekestle.com/articles/battery
In this article
What the laptop can measure
Why the estimate drifts
What wears a battery out
A short routine that works
Technology9 min read
Why your laptop’s battery percentage is only a guess

Most of us treat the battery percentage as a fuel gauge. It is closer to a weather forecast: your laptop cannot measure the energy left in its battery directly, so it estimates it.

Why the estimate drifts

A small chip combines the battery voltage with a model of how that battery behaves. The trouble is that voltage is a blurry signal for most of the range.

What wears a battery out

The model depends on knowing the battery’s full capacity, and that capacity shrinks as the battery ages.

A short routine that works

A battery that sits at 100% on a warm desk ages faster than one that spends its life between about 20% and 80%.

battery1 / 11↑↓×

By the numbers

Updated every Thursday

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142

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minutes: the average article

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The words on the page stay where they were. The reader is the part that moves.
Ingrid SolbergFrom “The case for reading the same book twice”

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Long reads on work, technology and everyday life, written to be understood the first time. New articles every Thursday.

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