Car batteries don’t last forever. Today, car batteries are supposed to last four to six years. However, most don’t last that long; usually, two or three years is the maximum. For whatever reason, they just don’t last a long time. This article will help you do a simple test on your battery to see if it is still good.
Check the Terminals
The terminals are the posts or flat areas on the battery that connect to the cables of your car. Make sure they are clean and free from any flaky white deposits. These deposits (or corrosion) can cause a bad connection and actually keep your car from starting.
If you need to clean the terminals, use gloves and goggles. This stuff is nasty. You can use a wire brush, sandpaper, or a terminal cleaner you can get at any auto store. When the terminals are clean, use WD-40, Vaseline, or grease from the car store to cover the terminals to help keep them from corroding again.
Fill with Water, If Necessary
Batteries that are not “maintenance-free” will have caps on the top. These caps can be removed. Following the battery manufacturer’s instructions, fill the battery with distilled water just above the plates inside the battery. Replace the caps. Be careful not to get any of the battery acid on yourself.
Turn the Key
The first thing to do is to turn the key in the ignition. When you first turn the key, the battery light (looks like a battery icon on your instrument panel) comes on. It should then go off when you actually start the car. This is the first thing to check to see if your battery is likely still good.
Drain Off any Surface Charge
With the car off, turn on the headlights for about two minutes to drain off any surface charge. Surface charge is basically the charge at the surface of the plates in the battery. So who cares? Well, testing a battery with excessive surface charge can lead to a higher (and thus incorrect) voltage reading. In other words, you might think the battery is putting out more volts than it actually is.
Attach Your Volt Meter
Shut off the lights and all accessories (radio, air, etc.). Shut off the engine. Set your voltmeter to read as high as about 20 volts. Connect the leads of your voltmeter to the leads on the battery. Make sure the positive is attached to the positive lead on the battery and the negative to the negative.
If you read about 12.6 volts on your meter, that’s pretty darn good. However, a battery may have enough volts, but not enough cold cranking amps (CCA) to start the engine. CCA is how many amps a battery can deliver at 0° Fahrenheit 30 seconds above 7.2 volts.
Start the Car
Keep the meter on the battery and have a friend start the car. When starting the car, the battery voltage should not drop down below 10 volts. If it drops down to 5 volts, you have a really bad battery. After starting the car, the voltage should jump to about 13 or 14 volts. This is because the alternator is now charging (pumping volts into) the battery.
Charging the Battery
You can charge a battery that is low using an off-the-shelf battery charger available at any auto parts store or on Amazon.com.
If you charge the battery and the next day it is really low, it’s not holding a charge and should probably be replaced.
Have a Professional Test it, if Needed
While this little testing process can help, you can also take your battery to nearly any auto parts or battery store and have them test it. They have much better equipment and will usually do it for free. It’s the best way to test if you want to be truly certain of the condition of your battery.