I have a Lenovo Y510p laptop. It uses a 120W 19.5V 6.15A rated charger and the connecter pin is 5.5x2.5 mm. I can neither find an original Lenovo charger nor a compatible adapter with exact ratings in my locality. My question is can I use a 120W 19V 6.42A adapter for ASUS that has the same connecter pin size of 5.5x2.5 mm? I know the 0.5V difference won't be much and the current rating is >6.15A, so the adapter should work fine. But would it be possible to use it as I can't personally test one and I was thinking of ordering one online.
So as far as laptop charges go, it's not a "one size meets all" as I'm sure you are aware.
The voltage must match. You have a 19V and a 19.5 - which is not ideal, but probably OK. It's a small difference, but sometime small differences can have bigger impacts on the lifespan of the laptop, for testing purposes, I'd be tempted to say you're fine.
Input voltage is usually a item to look at but nowadays it's hard to go wrong.
The amperage (the maximum it can supply) must be the same or MORE than your laptop requires. So if you're original is 6.15A, and the new one is 6.42A then fine.
The polarity is what catches people out, you should make sure the polarity of the new charger matches the laptop, otherwise you risk damage or shortening the lifespan of the laptop/battery.
So you'll want to check the polarity matches too:
So at the crooks of it,
Voltage should match, or worst case be as close as possible.
Polarity must be the same
Amperage must be the same or greater than required.