How does a slice battery actually work?

[UMPC2024]

When a 28++ slice battery is attached, does it 1) get used first and then the primary battery or 2) the primary battery is used first and then the slice battery or 3) does it run at the same time as the primary battery?

[theterminator93]

If the battery is attached and locked, the system will draw power from it first until it is depleted, then it will draw from the primary battery.

[brchan]

The slice battery will drain to 0%, then use the main battery. This is a well criticized problem, starting with the old ultrabay bay batteries. There was a way to change the discharge/charge thresholds on ultrabay batteries (and probably the slice batteries) in linux using a script, but it was no longer supported with the T430 generation.

With the dell models, you could easily control charge/discharge thresholds and even make the batteries drain at the same time.