Wall switch is a killer HP Elitebook 8540p

[davidh1026]

When the laptop is running normally on the AC adapter, it dies instantly if you flip the wall switch that powers the wall socket the adapter is connected to. However, if you just pull the adapter plug from the back of the laptop, the laptop continues to run on the battery. Is this normal? Seems odd.

[dneilson]

No, that is not normal. Have you tried another different outlet? If you try it in another outlet and it does the same thing you have a defective adapter.

[davidh1026]

Thanks, I'll try that.

[fink]

It sounds like there's some kind of power spike when the ac current is cut. Normally that should not reach the laptop as there would be voltage/spike suppressors built into the power adapter (or should be).

As suggested it could be defective or a badly made knock-off. Also worth trying as a little test, instead of hitting the wall on/off switch just pull the ac plug and see if it does the same thing.

[davidh1026]

The ac adapter is the OEM HP. Changing wall sockets made no difference. If you just unplug the cord at the wall or at the adapter (power cord is detachable) you get the same result. I did notice this, however; If you are just in the bios or NOT booted into Windows, the laptop dies even when you disconnect the adapter plug at the laptop. Windows appears to be helping the transition to battery power somehow.

[Shinma]

Check that the following does not apply: HP Notebook PC AC Power Cord Safety Recall and Replacement Program

[Steve R Jones]

There is probably a setting in the bios on what to do in the even of a power failure...

There won't be an option about "light switches."