02-24-2014 05:40 AM
just found a strange bug:
If you disable WiFi on a W540, and the airplane power mode kicks in, 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 bug is present on all the W540 machines I have tested on here at our site. Have reported it to the local Lenovo support center as well.
All our machines have Windows 8.1 with all the latest drivers.
Solved! Go to Solution.
02-24-2014 09:38 AM
Airplane power mode means limiting the 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 - it's minimum power budget is around 100 Watts. 65W AC adapter can be used to charge W540 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. So let me investigate this issue and get back to you later.
02-24-2014 05:32 PM
I talked to software team about this and found out that it's working by design. Basically it's a difficult situation because W540 can't support such low AC power provided by airplane. So, when airplane power mode is enabled, the effect is that W540 doesn't see any AC adapter at all.
In your case, you are actually enabling Airplane Wireless mode of Win8, but we synchronize airplane wireless mode with airplane power mode.
So we want to understand your use case. In what situation do you enable airplane wireless mode when you have AC power attached?
02-24-2014 10:55 PM - edited 02-24-2014 11:05 PM
Well, for once i have to say that it's not working 100% by design here. Because when i was debugging this issue I saw that I could get a charge for 1-5 minutes when changing to another battery. Not sure what could be the reason for that, but the machine did not cut off all adapters as it should by your description.
A general usage scenario where I would turn off WiFi (just pressing F8, and therefore entering Airplane mode) could be that you want to make sure your computer is offline when you are somewhere without a ethernet connection, or you want to "force" and be sure that the machine is only on ethernet (for instance on a LAN with an unstable ethernet connection that connect/reconnect every once in a while).
Another scenario is that you have been in a non-wireless zone, like an airplane, and forget to turn WiFi on again - leaving you with a machine that wont charge.
Either way you end up with a user believing that something is broken. This is an issue for Lenovo, because this will most likely make the end user call in in to the support center an they will replace either the power adapter, battery or motherboard (my support center had a motherboard replacement as their only option to try to fix this - and replacing 7 motherboards for no actual reason isnt good business for anyone).
Wouldnt it be a quick fix to make the WiFi on/off switch not automatically enable airplane mode, or at least bring up a popup informing the user about this limitation so they dont think its broken?
02-25-2014 06:19 PM
I get your point. It seems to be a conflict of two things:
So pressing F8 button has the effect of turning on airplane WIRELESS mode which has the effect of turning on airplane POWER mode which has the effect of disconnecting AC power on W540.
Every other system (besides W540) supports airplane POWER mode without disconnecting AC, so it's not a problem for other systems. It's just unique problem for W540. So let me discuss it within Lenovo and get back to you later. I'm sorry for this inconvenience.
03-12-2014 10:43 AM
For short-term the next version of Lenovo Settings Dependency Package will allow you to set a registry entry to avoid this situation. For long-term we need some GUI changes that will take more time.
I think short-term solution will be available soon (this week or next) but I'm trying to confirm now.
03-27-2014 08:17 AM
Finally I have an update about this issue:
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:
2. apply a registry configuration:
04-23-2014 10:50 AM - edited 04-23-2014 10:52 AM
Glad I found this thread!
I'd decided to use airplane mode as a shortcut to turn off bluetooth when my T440p was docked (since Microsoft in its infinite wisdom decided to remove a simple bluetooth on/off switch) but when I restarted I got the strange alert "AC power is detached from your docking station" (which it wasn't). now I know why.
Quick question -- what exactly does that registry hack do? Does it disable airplane power mode altogether, or allow the machine to draw 65W?
And while I'm here, does anyone know a quck way of turning bluetooth on and off (without having to drill down into PC settings)?