How to Test a Car Battery with a Multimeter
Hey there, I’m an Interstate Batteries pro and I’m here to show you how to test your battery like a pro. As with most things, it’s always better to get a checkup before things get worse.
Now, when is it a good time for a test? Well, for starters a battery is at its best for three years, so, if your battery is three years or older it’s a good time to keep an eye on it. There are a few signs of a bad battery: for example, you may get a battery icon on your dashboard like this one. There’s also the smell of rotten eggs; this is a battery that is overcharging. Ugh! You never get used to that. That’s not good. So don’t go near that battery. Get that stinky thing to a pro like me and we’ll check it out.
Here’s another one, you start the engine but all you get is this noise: [Car engine sputtering] Or you check the battery and realize it’s swollen like a football, also not good. Now, the older your battery, the more vulnerable it becomes, especially when the weather makes a big turn. So before summer hits with those high 90s or winter drops below freezing, check your battery to make sure it’s in good shape. And often a low battery can be caused by charging too many devices for long periods of time, severe temperatures both hot [Phew] and cold. Driving shorter distances and jump-starting multiple times can also be to blame. Whatever the reason, a test is always a good idea if you’re having concerns. The last thing you want is a dead battery when you least expect it.
So how do we pros test car batteries? It’s easy, all you need is one of these bad boys. It’s called a multimeter. You can find them at your nearest car part store as well as online. These neat little devices are used to measure the voltage of your car battery. Now, this may look like a piece of alien technology, but it’s actually very easy to use. Let’s get started.
First, turn the headlights on and leave them on for about two minutes. [Activating headlights] This will get rid of any surface charge the battery may have. While you wait, set the multimeter to 0 to 20 volts. Has it been two minutes? Just about. Let’s kill the lights. [Turns off lights] Now, locate your battery and connect the multimeter to the positive and negative terminals. I’ll give you a moment to locate and match the terminals. The positive terminal is usually red with a plus sign on it. The negative terminal is usually black with a negative sign on it. Good to go? Great. Let's check that multimeter screen. You should have a resting voltage of around 12.5 volts. Now, just because your battery registers around 12.5 volts doesn't mean you have a good battery, but that's what we are about to find out.
Now let's go start the car. [Car engine starts] Turn your car on, I'll wait. [Music plays over radio] Once you've turned your car on, go and take a look at the multimeter. What you want is to have a voltage higher than 13 volts. If the voltage is lower than 13 volts, you could have a bad alternator or a bad battery. This battery is not good. But, it's not over. There are still a few things we can do, like clean the connectors or give it a charge. Now, if you don't have a multimeter, pay attention to the telltale signs of a bad battery and never hesitate to take it to your nearby Interstate Batteries pro, they're always ready to help you check to see if the battery is wet, check water levels, check connectors, as well as run tests to let you know what the internal levels of the battery are and measure the reserve capacity.
Want more information on the health of your battery be on the multimeter? Come see your nearest Interstate Batteries pros to get an advanced diagnostic test that can tell if your battery needs to be recharged, replaced or if there may be another system to evaluate like an alternator. Remember, the more you pro, the more you know!
For other videos like how to charge your battery or how to jump-start your battery, click here. And remember that you can always take your weak battery to one of the 150,000 pros like me who are always ready to help just around the corner. Find one now.