It matters little that on many devices battery is always engaged, even if device is plugged into a wall. My Dell's laptop battery died even though I probably us

It matters little that on many devices battery is always engaged, even if device is plugged into a wall. My Dell's laptop battery died even though I probably used the laptop disconnected from external power source for less than 10 hours over its lifetime (two years). Interestingly, I had to physically remove the battery to be able to use it again when plugged into a wall, it wouldn't even turn on with a dead battery, even if connected to power source.