lappy power

[Cogman]

Quick question, I did something stupid and left my power cable for my laptop at home, I have another device near me that is able to output 9V and 1A of power. If I plugged it in to my laptop (it does appear to fit btw) would it do any damage to it and would it charge it at all? I remember reading that higher amps is a no no, but what about the lower ones? I know that it would charge slower, but I wonder if it would do damage. And I do know that I would be unable to run it while plugged in. Thnx for the help.

 

[ark42]

You absolutely need same voltage, same polarity, and same plug size.
Polarity is the little diagram with the + and - pointing to the inside or the outside parts of the plug, since it can be either way.
I'm not 100% sure, but I think the Amp rating is the max that power supply device can do, so you need to have the same or higher rating, or you will blow a fuse / melt the power supply / cause a fire / cause a voltage dip and thus just not work.

Edit: missed the topic summary - my guess is the laptop will try to pull the same amount of power, and with only 9V it will try to suck in about 8amps, which is 8x too much. Don't risk it.

 

[Cogman]

what if the laptop is turned off? will it work?

 

[ark42]

Somehow I doubt it. Its either going to do nothing since the voltage is too low, or its going to try to suck the amount of power it needs at a lower voltage, thus using more Amps then it would normally need to get the same number of watts, and since the power supply is only rated for 1A max, you're going to break it.
My guess is that 19V x 3.8A = 72.2W max, so 72.2W / 9V = 8.02A, over something with wires/circuitry only rated for 1A max (and thus 9W max). Either way, if the laptop can suck any juice, its going to be sucking up 8x what that thing is rated for (8x amp and 8x watts). Plan on it melting. Unless the laptop just refuses to do anything with 9V in which case nothing happens, you don't break the power supply, but the laptop isn't going to get charged either.