How to Test a Laptop Charger

By Brandi Berry-Fulton

Laptop computers are one of the many items that we use that depends on a rechargeable battery to keep it up and running. When your laptop fails to stay charged or to charge at all, it is time to troubleshoot the issue on your own before paying a professional. First test the charger to make sure that it is working properly.

Things You'll Need

  • Power source
  • 12-volt battery charger
  • Laptop battery
  • Cotton swab
  • Emery board
  • Voltmeter

Step 1

Be sure that the charger is plugged into a working outlet and getting power.

Step 2

Try to run the laptop from the laptop charger only; if it will not run off the charger alone then the charger is faulty or no longer any good. In some cases your laptop will run off the charger, but the charger will not be strong enough to charge the laptop. In this case you have a faulty charger.

Step 3

Try charging your laptop with the laptop powered off. Sometimes the charger will charge the laptop when it is powered completely off, but not when it is on. If it only charges the battery when the laptop is off, then you have a faulty charger.

Step 4

Check the battery for corrosion and/or leakage. If there is a sign of either corrosion or leakage you will need to stop attempting to use the battery pack and replace it immediately.

Step 5

Test your charger with a voltmeter. If it is an AC charger, set a voltmeter to 25 VAC. Make the contacts and probes touch, and look for a reading. If there is not a reading on the meter, the charger is not any good. For DC chargers, set a voltmeter to 25 VDC and make the contacts and probes touch. The meter should read at least 1V more than the chargers rating. If it does not, the probes need to be switched.

Tips & Warnings

  • Check the contacts. The contacts are the metal strips or points that can be found on the laptop and the charging base. Unplug the charger if you have not already and wipe the contacts clean with a cotton swab. Now check for visible corrosion; if there is any visible, remove with a fine emery board.