Using a multimeter to check your batteries is an excellent way to know if they are holding a charge or not. If you measure a voltage lower than the stated voltage on the battery, the battery is bad and should be replaced. However, take care to dispose of used batteries properly as it is unlawful and unethical to dispose of them in the trash. Take your batteries to your local recycling centre for disposal to prevent envirornmental problems.
Charge the batteries in a battery charger. Make sure the batteries you have are rechargeable.
Remove the batteries from the battery charger.
Turn the multimeter on and place on the DC volts setting.
Touch the positive lead to the positive terminal on the battery and the negative lead on the negative terminal.
Read the output on the multimeter and compare to the voltage rating of the battery. If the voltage is significantly lower than the rating, the battery is bad.
Remove the batteries from the charger as soon as they are done charging to avoid damaging them.
Wear safety glasses to protect your eyes from injury.