Background: Hello. I am an Electronics Engineering student, and while I am familiar with basic power concepts and power circuits, I don't know how laptops are generally built and I want to cross check this before I purchase an adapter.
Specifics: I have a Lenovo Yoga 510-14ikb which uses a 4.0-1.7mm barrel jack to charge. The power adapter is rated for 20V 65W. I want to buy a USB C to 4017 barrel jack "decoy", which negotiates 20V from a suitable USB PD powersupply/charger and feeds it to the laptop.
Question: As USB PD chargers are designed to default to 5V output, it is bound to happen that the charger will give the laptop 5V. Maybe for a brief time, or that it will fail to negotiate the needed 20V. So, how would most laptops react to this? Would it damage the laptop, or would the laptop possibly overload the charger?
I am trying to rule out that this pairing will cause malfunction or something serious. Help is appreciated.