Can You Charge a Laptop with a Phone Charger?
It depends on the laptop and charger. Many modern USB-C laptops can charge from phone chargers, but at a slower rate. The charger must support USB Power Delivery (PD) and provide sufficient wattage. Laptops with proprietary charging ports cannot use phone chargers.
Key Takeaways
- USB-C has enabled universal charging across devices.
- Gaming laptops and workstations typically require more power than any phone charger provides.
- Older laptops with barrel connectors or proprietary ports cannot use USB chargers without adapters.
Explanation
USB-C has enabled universal charging across devices. Laptops that charge via USB-C can accept power from any USB-C PD charger, including phone chargers. However, phone chargers typically provide 18-30W, while laptops often need 45-100W for optimal charging.
Using an underpowered charger may result in very slow charging or only maintaining battery level while in use rather than gaining charge. Some laptops will not charge at all if the power source is below their minimum threshold.
Always use chargers that support USB Power Delivery protocol for laptop charging. Standard USB chargers without PD support may not work even if the connector fits. Check your laptop's specifications for minimum power requirements.
Wattage is the critical factor. Most ultrabooks like the MacBook Air, Dell XPS 13, and Lenovo ThinkPad X1 Carbon require 45-65W for full-speed charging. A typical phone charger delivering 20-30W will charge these laptops at roughly half speed, often taking 4-6 hours instead of the usual 2 hours. However, lightweight Chromebooks and tablets with keyboard docks may charge at near-normal speed from a 30W phone charger since their power draw is only 30-45W.
There is no safety risk to using a lower-wattage USB-C PD charger with a laptop. The USB Power Delivery protocol negotiates the correct voltage and amperage between the charger and device automatically. The laptop will simply draw whatever power the charger can safely provide. However, using a non-PD USB-C charger that delivers only 5V/2A (10W) will be essentially useless for most laptops and may not even register as a power source.
Things to Know
- Gaming laptops and workstations typically require more power than any phone charger provides.
- Older laptops with barrel connectors or proprietary ports cannot use USB chargers without adapters.
- Charging while the laptop is off or in sleep mode requires less power than while actively in use, similar to how plugged-in devices use electricity even in standby.
- Some laptops like certain HP and Lenovo models display a 'slow charger' warning and may throttle CPU performance to reduce power consumption when connected to a charger below their recommended wattage.