Talk · Selection · Wired GaN chargers: wattage, ports & protocols

Why does a multi-port GaN charger lower the power when we plug in a second device?

The rated wattage is a total. When a second device connects, the charger shares it between ports, and the split follows the model's power-allocation table.

Wecent Editorial Team Updated 22 Oct 2026 3 min read

The question

Our customers bought a 65W 2C1A charger (WET-67-ACC). A laptop charges at full speed on its own, but when a phone goes into the second USB-C port, the laptop slows down and sometimes stops for a second. Is the charger faulty?

Main answer · Wecent Editorial Team

Short answer: Probably not. On multi-port chargers the rated wattage is the total for all ports. When a second device connects, the charger reallocates power between the ports, and the laptop is often renegotiated, sometimes after a brief interruption. The model’s power-allocation table tells you what to expect.

How the power gets shared

A 65W 2C1A charger has 65W in total to share. Used on its own, one USB-C port can usually offer the full rating. When a second port is in use, the charger runs a fixed set of splits, for example one higher-power C port plus a smaller second output. The exact values differ between models, which is why there is no general rule; the datasheet’s port-combination table is the reference.

USB-A ports and USB-C ports also often share one converter stage. On some designs, using A and C together lowers both to a basic profile.

Why the laptop pauses

A USB PD sink only takes the power profiles the source has offered. When the charger needs to change the budget for a port, it sends new offers, and the device has to negotiate again. Depending on the charger design and the device, this happens smoothly or as a short drop-out where the laptop briefly stops charging. Some designs renegotiate every port when anything is plugged in. A brief, one-off interruption at the moment of plugging in is usually normal.

When it is not normal

Charging keeps cutting in and out while nothing is being plugged or unplugged.
Power stays below the table’s value for that combination, with a cable rated for it.
The charger gets very hot, smells, or makes a loud noise.

These cases call for a test with known-good cables and, if they persist, a return through warranty.

Practical steps for your listing and support

Ask Wecent for the power-allocation table of the exact model and port layout (2C1A, 2C2A, 3C2A) and check it on a sample with a USB-C power meter.
Publish the table on your product page and in the manual, including which port to use for a laptop.
Advise customers to plug in the laptop last or first, consistently, if pauses bother them.
For 140W multi-port models such as the WEG-140W-2A3C or WEP-140-CCAA, check separately what the laptop port offers once phones are connected.

Facts cited here come from the named standards bodies, regulators, Apple support documentation and Wecent product pages. Points marked “ask”, “confirm” or “check” are recommendations or open questions to settle with your supplier, not verified specifications.

Three more perspectives

Wecent Editorial Team · Purchasing perspective

When you compare multi-port models, ask suppliers for the full port-combination table, not just the headline wattage. Two 65W chargers can behave very differently with two devices connected. The table is what tells you whether a model fits your laptop-plus-phone use case.

Wecent Editorial Team · Compliance/QC perspective

Add a two-device check to pre-shipment inspection: laptop load on one port, phone load on the other, then verify the voltage and current for each combination against the table. Single-port output tests can pass while multi-port behaviour fails. This check catches firmware or configuration mix-ups between batches.

Wecent Editorial Team · After-sales perspective

Most “charger stops when I plug my phone in” tickets can be solved with one help-centre article that shows the port table and a short explanation of renegotiation. Ask customers for the device models, the ports used and the cable rating before you approve a return. Without those details, many returned units test as fault-free.