How to Check or Test a Bad Battery
People change out batteries all the time but never check to see if the batteries are actually bad or not. Check to see if your batteries are completely drained before sending them off for recycling.
Things You'll Need
- Digital multimeter
Set the multimeter to its "check battery" setting, insert the two leads into the multimeter and turn it on. Test your batteries one at a time. The battery should be marked with a plus sign for the positive end and a minus sign for the negative end. For AA, AAA, C and D batteries, the bottom of the battery with a flat surface is the negative end; the top end of the battery with a dimple is the positive end.
Hold the black lead of the multimeter on the negative end of the battery, and gently touch the red lead to the positive end of the battery. Check the voltage readout on the multimeter. It may take a second for the meter to settle into a stable reading.
Recycle the battery if it does not have a strong reading. For a battery to be good, the reading should be close to or higher than the battery's rated voltage. For example, AA batteries are 1.5 volts. A new AA battery might show 1.58 volts on your multimeter. If an AA alkaline battery only reads 1.24 volts, the battery needs to be replaced.
Tips & Warnings
- Always recycle batteries; do not put them in the trash.
- Wear safety goggles, use gloves and work in a well-ventilated area when working with batteries.
- AAA, AA, C and D batteries all are 1.5 volts. A 9-volt battery is obviously 9 volts. The rectangular batteries used in camping lanterns are usually 6 volts.
- Do not test lead acid batteries using a multimeter.
- If a battery looks worn, damaged, discolored, smells or has an odor or is leaking, replace it. Protect your skin and eyes when working with damaged batteries, and use extra care to not get any residue on you.