Testing a laptop battery allows you to determine if it has any remaining charge. The best way to test a battery is to connect it to a laptop and turn the unit on. However, there are several other ways to determine if your laptop battery has any charge.
Test your laptop battery with a test light. Check the test light first to make sure it works. Connect the light to a metal ground source. Check the test light on a battery that you know works. If the test light glows, it's good. Place the light's test end into the battery's positive port. If the light glows, your battery is good.
Check your laptop battery with a battery tester. Put one end of the tester in the battery's positive port, and the other in a negative port. The tester will read how much life is in the battery, if any.
Hook your laptop battery up to a multimeter. Follow the process in Step 2 to connect the meter and determine how much charge is left in the battery. Most multimeters are electronic, but some have gauges that move to a certain point.
Place the laptop battery on a battery charger. These are mostly used for cars. Battery chargers generally indicate if a battery is good, bad or needs a charge.