Multimeter Car Battery Test

Almost everyone has suffered the particular nightmare of a dead battery.

You’re running late for work and the car refuses to start.

You’re in a parking lot late at night. It’s dark and you’re all alone and all you want to do is go home but when you turn your key, nothing happens.


You finally went on that road trip with your friends. You stop to take a few photos at a picturesque site and when you go back to your car, it’s dead.

Now you’re out in the middle of nowhere with no cell signal and no one around to jump you. There are just a few of the scenarios that can happen to you if your battery bites the big one.

The thing is, you can prevent battery drain by just doing a regular check up. A multimeter car battery test is the perfect way to go, too.

Let’s do a deep dive into why this gadget is a necessary addition to your garage.

Car Battery Drainage Woes

Sooner or later, you’re going to have battery problems. It’s one of the most common repairs you’ll ever need. Understanding the entire system is crucial to making sure you’re never stranded with a completely dead battery. The most obvious way to drain your battery completely is to accidentally leave your headlights on.

There are other smaller ways human error comes into play.

For example, you could forget to close your trunk all the way. The little light inside, innocuous enough, is enough to seriously deplete your battery. Or how about those little overhead lights? If you needed to look for something in the dark and then exit your vehicle, forgetting about them, they’ll drain your battery. You might also forget your car doors are open and the overhead light keeps your battery running. But there are other reasons your battery might die that don’t factor in human error and this is where a multimeter car battery test can be handy.

For example, you might suffer from parasitic drain. That’s when components of your car remain active even after you’ve turned your car off. You might not have a problem overnight but let it go for long enough and your battery will definitely die. If you’ve got a problem with your charging system, that’s going to turn into a problem with your battery sooner than later. Many of your car’s functions – like radio, lights, etc. – are powered through the alternator.

If your alternator is out of whack, it causes a drain whenever it’s charged.

Even if you get a jump, if your car has a charging issue, it will continue to drain your battery.

Your alternator can also have a bad diode, which causes the circuit to charge even if your engine isn’t on.

All of these are a recipe for battery disaster and can potentially leave you stranded.

A multimeter car battery test is one way to take a deeper look into the problem.

check battery voltage

Old Car Battery? How To Tell If It’s Time To Toss It

The average length of a battery’s life is around five years, sometimes a little more or a little less.

If you’re not quite sure where your battery is on its lifespan, a multimeter car battery tool can point you in the right direction. Old batteries can definitely drain your car’s power, but luckily, they’re one of the easiest things to replace on your car.

Here are a few signs that your battery is about to kick the bucket:

  • Your engine doesn’t start but you hear it crank
  • You’ve already had to jump it more than once
  • One day your car is good to go, the next day it won’t work at all
  • It won’t crank or start and the lights won’t come on

If this sounds like what you’re going through with your car, more likely than not,  you’ve got battery problems. To make absolutely sure, use a multimeter car battery device to make sure. If it does come down to throwing out your old car battery, rest easy; they have a high recycle rate.

So now you know how a multimeter car battery tool can help you; how do you use it? It’s beyond easy; keep reading.

car battery measuring

Using A Multimeter Car Battery Device For Accurate Readings


When working with electricity, you want to do everything safely. Take all necessary precautions and make sure you follow the manual.


Always wear gloves and safety glasses when you’re running your test. Better safe than sorry!

First, find your battery. You might laugh, but it’s easier said than done. Most car batteries are in pretty obvious places but car manufacturers have been known to hide them in weird places. Car batteries might be stuck under a plastic covering; others might even be in the wheel well. If you can’t find your battery at first glance, check your owner’s manual.

Next, make sure your car’s ignition and lights off. Now it’s time to get your multimeter car battery reader out. A multimeter car battery tool is pretty small, just a handheld device with a simple readout and two wires running from it. The wires should be red and black for positive and negative, obviously. Get your black lead and touch it to your car battery’s negative cable. Do the same with the red lead but connected it to the positive node.

If you touch the wrong one to the wrong node, you’ll just get a negative readout. Remember to keep red to red and black to black. Make sure to keep your multimeter car battery tester set to DC instead of AC. AC is a measurement that works best for household appliances. Set your multimeter car battery tester to 20 volts.

Now it’s time to interpret your readings.

Reading A Multimeter Car Battery Display

When reading your battery, the average temperature is 80 degrees Fahrenheit. The readouts change .01 percent with every 10 degree change in average temperature.

Here’s a guide to understanding your multimeter car battery readout:

  • If your tool reads 12.66 volts, your battery is 100% charged
  • 12.45 volts = 75% charged
  • 12.24 volts = 50% charged
  • 12.06 volts = 25% charged
  • Anything 11.89 volts and lower, your battery is at 0%
battery test multimeter

Once you know where your battery falls on this readout chart, you can start figuring out what you want to do.

Unless your battery is 12.45 volts and up, you’ll probably want to recharge it, replace it, or get a professional opinion.

If you need to recharge your battery, check it again later to see if it’s holding its charge. If not, you’ll know you have a bad battery on your hands.

Give your battery another check after recharging it to see if you’ve figured out the problem.

What About Using A Clamp Meter?

You might feel that a clamp meter is better than a multimeter car battery test. When you’re just measuring car batteries, a clamp meter is overkill.

Clamp meters are great for giant HVAC units and other pieces of serious equipment.

Their readouts go much higher, often up to 1000 amps. Multimeter car battery devices don’t go nearly as high, sticking to around 10 or 20 amps.

As such, clamp meters can be pricier than multimeter car battery testers. And really, do you need that much power?

You’re more likely to check smaller devices, like your car battery, than you are to come in contact with heavy equipment.

Obviously, if it’s your job to monitor larger units, go with the clamp. Most households are better served with just a plain multimeter.

Convenience And Accuracy

Now that you know all about how easy and convenient it is to use a multimeter car battery tester, you’ll want one for yourself.

They’re not just handy for cars; they’re great for testing other household appliances like dishwashers, washing machines, and dryers.

It goes without saying that it would be good to have one around to reach for when your devices go on the fritz.

Remember those scenarios we outlined before?

  • Getting stuck in the middle of nowhere without cell signal and no hope for a jump.
  • Trapped in a remote parking garage after hours in the dark.
  • Being late for work – or even missing it completely – due to a dead battery.
voltage test

All of these things are incredibly preventable. Just break out your easy to use multimeter car battery tester and take a few moments on the weekend to give your battery a check up. You’ll save money, too. Imagine that you toss out a perfectly good battery thinking it was completely dead.

Add this multi-use tool to your personal arsenal and take control of your finances and your car’s maintenance.

There are a lot of cool tools out there and the multimeter car battery tester is just one of them.

If you want to keep on top of the best tools that are out on the market, stick with Tool Nerds.

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