I forgot my charger at home but really need to get my pc running. I have a charger from a friend of my my pc has an output of 19V / 7.1 A and the friends has 19V/ 4.3 A. I know that the charger might overheat but what if I only charge when my pc is turned of will it still draw as many electricity when it is turned off? And I have a bit of a problem finding the polarity of my pc I found the one on the charger though
Edit: Found another one 19,5 V and 6,7 A should that one work
I'm not sure on how you've worded the question. If the amperage the machine requires is higher than the power supply can provide (In this case, if the PSU provides 4.2A and your laptop requires 7.1A), this is a problem and you should not use it. Your laptop may attempt to draw more power than the power supply can provide, and cause damage to the unit. If, however, you mean the power supply can provide a greater amperage than your machine needs (EG. your machine requires 4.3 A and the PSU provides 7.1 A), this is fine to use.
Do not attempt to power up your machine with it until you are sure of the polarity and the PSU is able to provide sufficient amperage, as if it's incorrect it could damage the power supply, the machine, or both.
The power supply on your notebook is a switched mode power supply. SMPS's powered of the power grid will always employ a transformer to archieve galvanic isolation. This has the sideeffect of limiting the amount of current that can flow (think of it like this: You can not blow out a fuse in your home by shorting the output of a PSU, because you are only shorting the secondary winding of a trafo). Therefore you won't burn anything. Unless you reverse the polarity, in which case you still won't burn anything, as the charging electronics on your nb's mobo will check for that.
The worst that can happen is that your nb won't charge.
