Laptop power & battery

Using the wrong wattage charger causes slow or no charging

Chargers below the laptop's rated wattage will still work in many cases, but they charge slowly or not at all under load, and it's worth confirming you have the right one.

Difficulty
Easy
Time
10–15 minutes
DIY cost
$15–$60
Pro cost
N/A

Symptoms

  • Charger works but charging is unusually slow
  • Battery percentage may even drop while using the laptop despite being plugged in
  • Charger brick is noticeably smaller/lower-rated than the original
  • Charging is fine when the laptop is idle but not under load

Likely causes

  • CommonCharger wattage below the laptop's requirementA 45W charger on a 65–90W laptop will charge slowly or only while idle.
  • CommonUsing a phone or tablet charger by mistakeThese are typically far below what a laptop needs.
  • PossibleCharger correctly rated but degraded with ageAn old charger can lose efficiency and effectively underperform its rating.

What to do

  1. Find your laptop's required wattage, usually printed on the bottom of the original charger or in the laptop's specifications.
  2. Compare that to the wattage printed on the charger you're currently using.
  3. If underpowered, avoid heavy tasks (gaming, video editing) while charging, since the laptop will draw more than the charger supplies.
  4. Replace the charger with one rated at or above the laptop's original wattage for reliable, full-speed charging.
  5. For USB-C laptops, confirm the replacement supports Power Delivery (PD) at the needed wattage, not just standard USB output.

Tools and parts

  • None required
Correct-wattage laptop chargerSearch: “[laptop model] charger wattage watts”

When to call a pro

This is a simple mismatch to correct by buying the right charger, not something that needs repair.

Safety

Generally low risk

Generally low risk for a careful person. Stop if anything looks different from what this guide describes.

Related guides

Operator provides AI-generated troubleshooting information. It can be wrong. For safety-critical, electrical, gas, structural, medical, automotive safety, or other high-risk problems, consult a qualified professional.