How to Test a Car Battery - Plus Tips on How to Prevent a Battery From Going Bad

Here is a very quick and detailed video on how to test a car battery using a multimeter. Also included are some tips on how not to mistake a bad battery with a bad alternator or a bad starter.

Here are Links to Tools and Parts Used in the Video:

You also might want to check out these other helpful videos:

[trickedouttech]

Factory CCA numbers are tested with a bottom number of 9.6v, not 10.5. However, that test is performed at low ambient temps. You can use 10.5V if the car has been running within the past hour or so. If the car is first to start of day 9.8 volts bottom number. If the car is the first start of the day and the outside temp is below 32 then 9.6 volts is the bottom number. No matter the case or temps the battery should not drop below 9.6v during startup. If the battery is below 9.6v during cranking at any time. You need to charge the battery run text again if fail to replace the battery especially if the weather is cold. It will leave you stranded.
Also, you should run headlights for at least 30 sec before the test. Removing any false charge sitting on top of the voltage. Especially if you charged the batter before this test. It is common practice to run headlight for 30 sec 90% of the time when performing this test. if you put the meter on the battery and volts are above 12.7 you need to turn on the headlight for 30 sec. Battery voltage should be 12.4v-12.6v give or take .9v.

[bassiclymike]

Great information as always!
I had an issue with my 2001 Explorer Sport where it would not start after just driving it. No power to headlights, power locks windows, radio, nothing. Checked and found that the wire connections to the terminal clamp were badly corroded. Similar to how the wires are connected on the back of the terminal clamp on the positive post in your video above. The connection between the post and clamp was in decent shape. I unbolted the wires from the back of the connector, cleaned it all off with a wire brush, including spreading apart the wire strands to clean the corrosion off of them. Once it was all reconnected, everything was fine. So that's another place to look for corrosion.

[spelunkerd]

It always surprises my how often people get this wrong. Even professionals sometimes forget to check the engine ground connection, and overall the diagnostics are not as easy as some people think. Your review is exactly right, especially the emphasis on load testing. Also it's worth emphasizing that a battery needs to be warm, electrolyte level is normal, and fully charged before before testing. I find doing the load test away from the vehicle avoids the confusion about bad connections, so your remarks about double checking the battery at a local store is great advice. 

[rudedoggonzo]

Just love this guy he's like family to me
I totally thank you!

[Calida]

This was very informative! Thanks very much!

[H.pylori]

Excellent instruction on how to evaluate a car battery. Now I understand what to do and what to look for. So, even though one of my cars is showing 12.3V, with a load, the output is not sufficient.

[moosecake]

FYI the cold cranking voltage is 9.6 volts or above and not 10.5 volts, other than that a great video!!

[johnlile]

Really appreciate all of your video's. You're definitely my goto guy on electrical issues. You're very thorough, and I write down everything. Will be tackling a electrical drop on voltage and amps soon with my little airplane. All of your video's give me confidence to hopefully get to the bottom of it. Thanks!

[naujcdl]

Excellent information and yes please post the alternator one.

[arturoG]

keep it up really simple and easy to understand thanks

[RGeno]

Good informative video man! It helped me out today.

[mariojacquez]

Very explanatory.... Great video... Thumbs up for sure... Appreciate the time and effort... Very informative...Keep'em coming..

[rkgki]

Another clear and concise video. Well done.

[owlru]

Good stuff, easy to understand "gracias".I'm going to test my battery tomorrow.The central locking is not working, there are no lights on the dash? Not sure what's happened, but the ignition fuse was blow, replaced that, but still no life? C'est la vie I guess

[Gunzee]

My car battery was sitting for about 2 months in low temps -2 to 5 C and it wouldn't start the car. I charged it drove it and it then sat again for a good 2 months in temps around 5 to 11 C, I didn't start it but checked the voltage which showed 12.4. My charger was giving 2 amps which increased to 3. Also if you have a bmw you can check volts on the dash by holding the trip reset until it flashes yes/no, select yes go to 19 then 9 (E46)

[jimnicosia]

Ratchets and Wrenches, can a car electrical system run from the alternator after the car is started and the battery is dead?

[abimariavargas]

What if starter is pulling more amps than normal will it affect readings.

[tnamen]

Sir, please kindly take take note on the question below...
Say, the battery is showing 12.7 volt on checking multimeter, however, checking gravity tests on each cell, if anyone shows reading out of range, should I confirm the battery is going bad???
Which is the best and correct to identify battery is dead and needs new battery??? Voltage reading or gravity tests????
Thanks.

[newyork]

Sounds good except for the part when you said when the battery is dead and there is nothing you can do; that was an inaccurate statement. Because I know you can recondition a battery to restore it. Just a saying.

[generatorblue]

Dirty terminal connectors = bad connection = battery not charging properly by the alternator.