I realize that if you disable WiFi on a W540, and the airplane power mode just kicks in.
As a result, the machine no longer recognize any chrging adapters, neither from the bundled adapter, or from the docking (135W)
If you re-enable the High Performance power option, charging is working again. This is strange.
This bug is present on all the W540 machines I have tested on here at our site.
All our machines have Windows 8.1 with all the latest drivers.
Any idea about the issue and how to fix it?
Before providing the answer, this is some info that you need to understand.
Airplane power mode means limiting the W540 system to 65W of power from AC adapter, regardless of what AC adapter is actually attached. This is to prevent overloading airplane circuit breaker.
W540 does not support 65W AC adapter because its minimum power budget is around 100 Watts. 65W AC adapter can be used to charge W540 only when it is sleep/hibernate/off, but 65W power adapter is essentially disabled while the system is turned on.
So this is the reason why airplane power mode causes W540 not to recognize any AC adapter, because airplane power mode limits AC adapter to 65W which W540 does not support.
The real question is why W540 ever enters airplane power mode which is not supported on this system due to power restriction.
Here's the current workaroun you can try to fix the charging issue at the moment.
Turning on airplane wireless mode of Win8/Win8.1 also turns on airplane power mode. On ThinkPad quad-core system like W540 and T440p, this has the effect of disconnecting A/C adapter.
1. Install the latest version of Lenovo Settings Dependency Package: