Why does a laptop say it’s at 6-8% charge, and then it dies, but when it’s at a higher charge, going from 60% to 59% takes a while?

Question

Why does a laptop say it’s at 6-8% charge, and then it dies, but when it’s at a higher charge, going from 60% to 59% takes a while?

In: Technology

Answer 1

I haven’t seen the actual reason posted yet – it’s because battery characteristics change as they’re cycled, and over time. State of charge is usually determined by measuring the voltage of the battery, but batteries lose capacity over time. In addition, the voltage of a battery going from full to empty is not a linear regression. If you assume full is 5 and empty is 1, for example, the voltage may be at 3.5 at 90%, 3.0 at 30%, 2.5 at 10%, before falling 2.0 at 1%, and 1.0 at 0%.

It’s tough to measure that accurately.