Testing Your Car Battery

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Testing your car battery is an essential part of routine maintenance for your vehicle. Most of the time, we wait until our car just doesn’t start to decide our battery is ready to be replaced. The reality is that a battery that gets your car started may be bad, while a battery that isn’t getting your car started may be in good shape even if your car wont start.

There are actually a few different reasons besides a bad battery that would cause your car to be slow to start so be sure to check out our article on slow starting before you go ahead and replace your battery.

Now, before we get testing on your battery it’s important to know what sort of results your looking for. Let’s talk about all the different numbers or ratings that might be on the label on your battery

Battery Ratings and Specifications

Cold Cranking Amps (CCA)
Cranking Amps
Reserve Capacity
Frame Size

The cold cranking amp rating is one of the most important ratings on your battery. That number usually between 500 and 1000 is the number of amps that battery is designed to be able to deliver at zero degrees Fahrenheit. A battery delivers it’s power by way of a chemical reaction and as you may have learned in science class in high school, chemical reactions tend to slow down and very low temperatures which is why CCA is measured at zero degrees.

Another number on your battery may be the cranking amps. This is same measurement as cold cranking amps, just performed at or above 32 degrees Fahrenheit. If you’re testing your battery yourself, chances are this is the number you’re matching to your test results to to get an idea of what kind of condition your battery is in. Cranking amps in general are about 20% higher than cold cranking amps.

Many battery, especially specialty batteries will also list the reserve capacity. This number will be listed in minutes and is the time your battery can discharge 25 amps before dropping below an unusable voltage. If you use your vehicle battery to power things while the engine isn’t running like an RV battery or a battery in a work truck, this number is very important.

The last number is the frame size sometimes called the group number and this tells you the physical size of the battery and orientation of the “+” and “-” terminals so you know it will fit in your vehicle.

Testing Your Car Battery: What the Results Mean

In the video here our battery tested out almost exactly at the cranking amps it was designed to have so we know it’s good. What if your battery tests out too low? Here are the numbers we go by:

100% – It’s Good!
70% – It’s time to start thinking about replacing it, especially if your cautious or are often in remote areas
60% – Start carrying jumper cables in your car, your vehicle may not start!
50% -You’re rolling the dice! A cold snap could definitely cause your vehicle not to start in the morning
30% – Your vehicle isn’t starting without a jump start!

Many local auto parts stores offer free battery testing so head out to one of our partnering auto parts stores and get your battery tested today!