Why the wide miss of Amperes means it's not a proper supply the new Dells and many other models do not charge the laptop without a third wire. It's pretty technical but the short version is you no longer can connect up any old power supply. There are not so new safeguards where the PSU and laptop "link up" and have a chat about make and model before starting a charge.

https://electronics.stackexchange.com/questions/327909/3-wires-on-a-bipolar-dc-plug-what-are-they-for dives into this. WHY? Because of battery fires.