Laptop charging

misterstingy

I have often wondered about laptop chargers. Perhaps someone knows the answer to these three questions:

1 If the charger is connected to a live electricity supply but the other end isn't plugged in to the laptop, does it use any electricity?

2 If the charger is plugged in to the laptop but not connected to a live electricity supply, does it drain the laptop or cause any other problems?

3 If the charger is plugged in to the laptop and connected to a live electricity supply, does the charger continue to use electricity after the laptop has become fully charged?

macman

1 and 2). No, because there is no completed circuit to allow electricity to flow.
My great aunt (supposedly) used to worry about huge bills arising from electricity 'leaking out of the sockets' when she first had a supply connected in the late 1940's.

wongataa

misterstingy wrote: »

I have often wondered about laptop chargers. Perhaps someone knows the answer to these three questions:

1 If the charger is connected to a live electricity supply but the other end isn't plugged in to the laptop, does it use any electricity?

A miniscule amount. Essentially no.

misterstingy wrote: »

2 If the charger is plugged in to the laptop but not connected to a live electricity supply, does it drain the laptop or cause any other problems?

No.

misterstingy wrote: »

3 If the charger is plugged in to the laptop and connected to a live electricity supply, does the charger continue to use electricity after the laptop has become fully charged?

See 1.

psychic_teabag

I'm not an expert, but...

1) an efficient charger should completely turn off. However, some could still waste a little power in rectifying and stepping down the mains voltage to the DC required by the laptop, even if no DC current is being drawn. If it feels warm, it is wasting a little power. If it's cold, it has shut off (almost) completely.

But it's probably not a good idea to just leave it live, plugging it in just when you want to charge the laptop - I have had sparks when (accidentally) doing this - presumably from accidentally making contact with the case or something. And I have heard of other people doing more serious damage.


3. I have heard this is a bad idea - once the laptop is full, it will stop accepting charge. Then discharge slightly, and start recharging. And that this constant cycling is bad for the battery. That said, I do leave my work laptop plugged in all day since I use it as a server and don't need portability.