Frequently asked questions
Can I charge my laptop with a lower-wattage USB-C charger?
Usually yes, but with consequences. If you plug a 45W charger into a laptop that requires 65W, the laptop will charge — but very slowly under load, or may only maintain charge without gaining any while the laptop is under heavy use. The USB-C Power Delivery (PD) protocol negotiates the maximum safe wattage between charger and device, so you won't damage the laptop, but battery percentage may drop while working if the charger can't keep up with consumption.
What happens if I use a higher-wattage charger on my laptop?
Using a higher-wattage charger is safe — the laptop's charging controller only draws as much power as it needs. A 140W charger on a laptop that needs 65W simply charges it at 65W. The overage is not forced into the battery. The only practical concern is paying for a larger charger than necessary; there is no risk of damage from charging with more watts than required.
Are all USB-C laptop chargers interchangeable?
Only chargers that support USB-C Power Delivery (PD) and negotiate the correct voltage profile for your laptop. Standard USB-C phone chargers (typically 5V/3A = 15W) cannot charge most laptops. Laptop chargers must negotiate PD profiles at 20V/3.25A (65W), 20V/5A (100W), or 28V/5A (140W, USB PD 3.1 only). Apple MagSafe 3 laptops can also charge via USB-C PD but use MagSafe for full wattage.
Why does my laptop charge slowly even with the correct wattage?
Several factors can limit charge speed: a USB-C hub or dock in the charging path that can't pass through full PD wattage; a cable not rated for the required current (always use the cable that came with the charger, or a rated replacement); thermal throttling when the laptop is hot; and "optimised charging" features in macOS and Windows 11 that deliberately slow charging to extend battery longevity.