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Sometimes I unplug my Thinkpad laptop from its AC/DC power supply adapter and keep the adapter connected to the power socket. Are there any possible negative consequences? Some ideas I was thinking about:

  • Clearly, it consumes electricity even without any load. How much can it be it?
  • The power adapter is simply operating longer, so it can age faster.
  • Perhaps the power adapter isn't designed to operate without any load and so it can age faster, or even get eventually damaged?
  • (Un)plugging the cable from the laptop with the adapter on can cause strain on the laptop circuitry (I don't know the proper English terminology - please feel free to correct). I was taught to always unplug/plug the power plug first/last for electronic devices so that the power adapter filters out any noise created by the contacts.

Is anything of these serious enough to be concerned? Are there other possible problems?

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I don't think you should be worried. Your laptop will probably be obsolete by the the time the power adapter goes regardless of "bad" practices. I would also suspect that the engineers who designed the power adapter would take your situation into account as it is a common one. But then again if it saved 10c per unit with a design that degraded if you left it on the wall socket but lasted long enough to cover the warranty maybe they would... –  jmathew Jul 3 '13 at 20:32
    
This is more the rule than the exception -- everyone does it. It wastes a little bit of power, but not much. –  Daniel R Hicks Jul 3 '13 at 21:16

2 Answers 2

up vote 4 down vote accepted

There should be no problem with keeping it plugged into the socket. With modern adapters there is no need to worry about the order you plug things in (unless you are superstitious). The only problem that I could think of would be the adapter getting hot - you forgetting about it being plugged in and maybe placing things on top of the supply that could potentially cause a fire but that is pushing it.

The other thing would be, as you mentioned, the fact that it is drawing power. However this would be such a small amount that you should not even notice it on your bill.

The overall answer is no, there is nothing wrong with leaving the power supply plugged into the wall while not in use.

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The adapter is cold when the laptop is unplugged, so I'd say a fire risk is small, as well as the power draw. –  Petr Pudlák Jul 4 '13 at 4:30
    
The only other thing i could think of would be if there was a power surge, the adapter could potentially get fried. lol Honestly i dont think there is any reason you should not do it. –  Atari911 Jul 4 '13 at 5:44

It could potentially incur damage if there's a power surge (e.g., lightning or power transmission event). Why not just use a surge protector (or even a regular power strip) with an on/off switch? This is a pretty common configuration, and lets you turn off the power to multiple devices (monitor, USB hub, etc) with the flick of a single switch.

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