When you have trouble starting your car, the world feels like a rotten place.
We get into our cars to go places and it’s a terrible feeling when the car won’t start. Taking it to the mechanic is frustrating and costly. Often the problem is a dying battery.
Let us show you how to test a car battery with a multimeter to save you some time and trouble.
Testing your battery isn’t difficult if you have a multimeter. These handy machines make the process quick and easy. Follow our tips and you’ll get good results in just a few minutes.
Here’s the whole process.
How To Test Car Battery Amps With Multimeter
Start With Your Multimeter
The first thing to do is to test your meter. Change the function to ohms and touch the leads together. If it reads 0 ohms, you’re good to go. When the leads are separated, the reading should be 1.
After this, check the owner’s manual for the amperage rating. Each multimeter model is built for a certain amount of current, and the rating needs to be adequate to test your car battery. You can do this by checking the owner’s manual of your device.
After you know your multimeter is working correctly, you need to select the appropriate function on your multimeter. When you measure amperage for your car battery, select for direct current amperage. You must do this because the power source for your system determines the type of current that would be measured.
The final thing to do is to set the range on your multimeter well above the expected readings. This creates a maximum amperage sensitivity of your device. You should do this to avoid blowing your fuse.
In situations where your multimeter is not reading anything when it is connected to your system, reduce the range of your device.
Now for the Battery
Your multimeter should come with two cables. One should have a probe in the end and the other should have a lead. Please ensure you plug the cords into the correct terminals.
Connect positive to positive and negative to negative. Also, your owner’s manual would be of great help to make sure you get it right.
Before you test the circuit, take care of yourself.
You should ensure you wear protection for your eyes, gloves for your hands, and other protective clothing. Another important thing is to remove all your jewelry because they may be conductors of electricity. When you are sure of your safety, then you’re ready for the test.
Turn on your car’s headlights for about 30 seconds. This will eliminate any weird charges going through your car’s system. Then, connect the multimeter leads to your battery terminals. Check the reading. Here’s a quick guide to the results:
- For readings that are over 12.5 volts, it means that your battery is charged and in great shape.
- If the readings range between 12 and 12.3 volts, your battery is operating at 75% and doesn’t need to be replaced too soon.
- Finally, if your battery is operating in critical condition and around 11.8 volts or less, this means that it is operating at around ¼ or 25% of its full capacity. It should be replaced as soon as possible.
Multimeter tests are used all over the world for good reason. They are fast, simple, and very reliable.
More load testing could be done, especially if you are expecting cold weather.
For most people, though, this guide on how to test a car battery with a multimeter should avoid common battery problems.
How to test a car battery without a multimeter?
There are other ways to test your car battery aside from the multimeter.
Either way, you can proactively inspect and prevent further battery troubles when you know how to check the status of your car battery.
Here are two other methods used by car owners and mechanics:
A very simple way to check your car’s battery is to use the headlights
To do this, turn off the car and turn on the headlights. Leave them on for about fifteen minutes. Once this period of time has gone by, start the car and watch the headlight’s brightness.
If the headlights dim dramatically, then the battery is weak. Slow starting or failure to start means the same thing.
This simple test can be performed anywhere and should reveal the state of your battery.
A weak battery is almost always headed towards total failure. You should replace it before you get caught out somewhere you don’t want to be.
Test the car battery with a Power Probe tool
Turn off the ignition. Remove the positive terminal and connect the red lead. Connect the black lead to the negative terminal. If the battery is healthy, then its voltage should be between 12.4 and 12.7 volts. If it is lower, then it is probably on its way to failure and should be replaced.
While the probe is connected, an assistant can crank the engine for you. If the voltage drops below 9.6 during a 2-second starter use, then the battery is not holding a full charge. A replacement should be installed as soon as possible.
How to properly charge a car battery?
The battery of a car, particularly the new ones, can stay charged by drawing power from the car’s engine.
Car batteries can go for 4-5 years before without needing replacement. There are also circumstances where good car batteries run out of power due to overuse or car defects that directly affect the normal charge and use of the battery.
So how can we recharge a car battery properly? Let’s walk through the process together.
Prepare your PPE (Personal Protective Equipment). Gloves and goggles protect your hands and eyes from most problems.
Prepare the Battery
Most batteries can be charged without removing them from the car. However, if there isn’t enough space for charging cables, then you should unhook your battery and remove it for easier access.
With the battery clear, you should ensure the terminals are clean. Light dirt can be brushed off easily. Heavier dirt or corrosion can be knocked off with a wire brush or removed with a cleaning fluid.
Make note of the kind of battery you own. There are about six different battery types, although only two or three are common in cars. Each one may require a different charger type. The owner’s manual and the battery itself should provide this information.
Charge the Battery
Obtain a car battery charger that is suitable for your battery and purpose. There are different kinds of chargers varying from fast to slow chargers and manual to digital chargers that can automatically stop the charging process once the battery is fully charged. Be sure to read the instruction manual of the charger to make sure that you can use it properly.
Check the cable attachments of the charger to the battery before turning on the charger. Connect the black cable from the charger to the negative terminal. Then, connect the red cable to the positive terminal of the battery. Be sure the cables are attached correctly to the battery. Mixing the negative and positive terminals could lead to battery damage and fire.
Set and plug in the charger. Choose the correct settings in the charger according to the charging requirements of the battery. After charging the battery, check to make sure it works. You can use the methods we’ve already explained to do this. If the battery is in the car, hook it up and check by starting your vehicle.
Bad Car Battery Symptoms
One of the most common problems car experience is a dead or flat battery.
Let’s have a look at these car battery issues that we come across frequently.
Old or Aged Batteries – Car batteries will always reach a limit. It may last a few years but at some point, due to constant usage, the parts will wear out.
With several factors which include extreme temperatures makes the battery drain over time. You will definitely need a new replacement once your battery reached its final stage.
Car is very slow to start – The engine cranks when you turn the key but the car starts slowly.
When you encounter this problem, get your battery tested.
Car won’t start – Turning on the ignition results in a long crank or just a clicking sound. If the problem is the battery, you can give it a recharge or a jump start and try again.
But if this is a recurring problem, the battery needs to be checked or replaced.
Your car needs multiple jump-starts – If you have this problem and have an old battery, then replace it and observe the results after replacement. If you have a new car battery but still you need jump starts, then check your battery.
Maybe you have a battery that prematurely wears out. You need to test your battery, check the warranty, and, if needed, replace your car battery. Your battery may be experiencing parasitic drains.
There may be a car part or component that uses the current of the battery even if the car is not in use. You need to inspect your car to prevent your battery from draining unintentionally.
Battery Corrosion – Blue corrosion or a clear film on top of the battery means your battery leaks the actual battery acid and could be emitting fumes. This lowers the battery’s voltage and its efficiency.
A temporary remedy is cleaning the battery, but the problem will return. It is better to have a battery replacement. The positive terminal cable end may also need a replacement if it’s damaged due to corrosion.
Frequently Asked Questions
How many amps should a car battery have?
The battery is one of the most important parts of a car. Most people know that a car’s battery is around 12 volts but don’t have any idea how many amps a car battery should have.
Starting a car engine with 4 cylinders takes around 300 cranking amps. This means that a car battery’s amperage is more than 300 amps. Car batteries have a capacity ranging from 550 amps to 1,000 amps (cranking amps) depending on the battery’s specifications.
Most (if not all) of the car batteries available in the market have these ampere capacities.
My car battery keeps on dying? What to do?
If your car battery keeps on dying it means that something is draining the charge from your battery fast. Try to remove the battery when you are not using the car (especially at night), then reconnect it when you are about to use your car.
If your car engine starts without a problem then it means that you are encountering a parasitic drain on the battery. You can check the car components you commonly use to discover what drains your car battery.
If the engine doesn’t start, then this means that the battery is not holding a charge. Try to recharge the battery with a battery charger. If it drains dramatically during the car’s usage, then it means that there might be a problem with your car’s voltage regulator or the alternator. Go to your trusted mechanic and let them check your car.
How long do car batteries last?
Normally a car battery will last for 3 to 5 years. A lot of factors can affect the overall battery lifespan. Deep discharges and high temperatures are factors that can shorten a car battery’s lifespan.
Battery life can also depend on the manufacturing quality and specification of the battery. You also need to consider how long the battery was stored in the shop unused before you bought it or was assembled in a car.
When purchasing a car battery, check the manufacturing date which is printed on the label. Newer batteries are better.
Is it better to charge a battery at 2 amps or 10 amps?
In charging a car battery, the lower (slower) the charge is the better. Charging at 2 amps of power takes a long time to charge the battery but there is an advantage to it.
Using a lower charging rate means that you are less likely to overcharge your car battery. Overcharging a battery can reduce a battery’s overall lifespan.
A 10-amp charger will charge your car battery quicker. It is still safe, but you must remember to remove the charger as soon as the battery is full. Don’t be caught out by the fast charging speed and overcharge your battery accidentally.