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My question is a bit like this, but more general.

I have a laptop with a USB-C port (Asus UX310UQ-FB442T in this case, but I'd prefer a general answer), and a USB-C PD charger with the necessary power (65W charger, the same power the laptop came with).

Can either of them (charger or device) be damaged if I connect the two to test if it can charge or not?

Sometimes specifications are faulty (apart from the USB-C, the laptop has 2 USB3 and 1 USB2 ports, and not vice versa) or not cover certain capabilities (like in the mentioned topic), so it's better to test it. But I don't know if a USB-C device is not PD-compatible, and the charger powers it externally, things might go bad.

Nyos
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1 Answers1

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The short answer, assuming everything is spec-compliant, is that no scenario should damage the laptop.

For a general answer, we can only talk specifications and assume all devices follow the spec. It's not possible to account for faulty implementations in a general sense.

USB-PD is a negotiated protocol, over the CC pins. Without the correct negotiation, a PD-capable charger will not output PD voltages. So, in that sense, you are safe.

There is a similar situation with plain Type-C (non-PD 5V) power: the CC pins are used to indicate whether one end is a power sink. Power sources are not supposed to apply current unless a sink is detected on the other end. A source-to-source connection, according to spec, will do nothing (power-wise). See Universal Serial Bus Type-C Cable and Connector Specification R2.0, in § 4.8 Power Sourcing and Charging, § 4.5.3.1.5 Source to Source Behavior, and various other locations.

There is the possibility of a dumb charger providing current without detection. This is still a safe situation if your laptop port follows specs.

All USB Type-C ports shall tolerate being connected to USB power source supplying default USB power, e.g. a host being connected to a legacy USB charger that always supplies VBUS.

Universal Serial Bus Type-C Cable and Connector Specification R2.0 § 4.6 Power

Bob
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