How To Check And Replace A Bad Car Battery

Nobody likes to be stranded in the middle of nowhere…

Especially if that could have been prevented by a routine check…

That’s what could happen to you if you’re not careful with your battery health.

In this article, you’ll learn everything you need to know about car batteries and how to avoid being a stranded victim of an empty battery.

Why Does Your Car Need A Battery?

There are more and more electronics in your car, right? From opening your windows to powering a complete onboard computer, nowadays cars are mostly managed by a lot of electronics components (maybe too many!).

But the actual main function of the battery is to start your engine.

That’s right, your engine cannot start by itself.

It needs to be started by a motor. When you start your engine the battery powers an electric motor called the starter. It rotates the crankshaft and starts your combustion engine. 

Starting an engine requires a ton of energy.

That’s why your battery is a key component of your car.

Especially in winter. A cold battery has more difficulties retaining energy. That’s why it is hard to start your engine in the middle of winter.

When choosing a replacement battery, you need to make sure to choose a battery that can deliver enough power to start your engine even in the coldest temperature of winter.

How To Check Your Battery

So you want to know if your car battery needs a replacement?

Here’s what you need to know.

First of all, batteries need to be changed every 3 to 5 years depending on your car use and climate.

Now if you want to diagnose your battery here is what you need to know:

Some cars display the following warning sign to let you know that the battery is low in energy and requires some attention:

But surprisingly most cars do not display anything on the dashboard when the battery level is low.

So how to know if your battery has a problem.

First of all, if you have absolutely no equipment, and your car doesn’t start or struggles to start, here are the symptoms:

The light on the dashboard blinks (as if there was not enough energy to power them)

The engine struggled to start right away. It turns over a little bit but stops right away. It means there is a little bit of juice left in your battery but not enough power to start your engine. 

Your engine does not start at all

You may encounter these troubles especially if it is cold.

To test your battery, you need to locate your battery.

For most cars, it is located in the front under the hood. But on some cars, it may be in the trunk for weight distribution.

The first thing to do before considering changing the whole battery is to make sure that the plus (red) and minus (black) connectors are not loose by giving a quick shake to the connectors. If you feel your connectors are moving, just tighten them up and that could simply solve your issue!

The second thing is to make sure that the connectors are clean and corrosion-free.

If your connectors are corroded (see picture) or dirty here’s what you can do.

Use a little bit of warm water and some baking soda that you mix together. Then brush your connectors. You will see some bubbling.

No worries, the bubbling just means that the acid on the connector is being neutralized. Then remove the connector from the battery and sand down the battery terminal to get a good connection. You can use 100 grit sandpaper,  an abrasive pad or just a metal wire brush.

Once you clean the wire and the connector, reconnect everything and try to restart your car. You can coat the battery terminal with some silicon grease to prevent moisture from getting in there and causing corrosion.

The Ultimate Battery Test

Now here is the best test to see if you test your car battery. You will need a multimeter which is a simple and easy-to-find tool.

Then set the multimeter to 12V or more (20V for example) 

As the battery ages over time, it simply loses its ability to maintain an optimum voltage to start your engine.

Let’s measure the voltage of your battery.

Touch the red probe to the positive terminal (red) and the black to the negative terminal (black) and read the measured voltage on the screen.

What you want to see is a voltage between 12.4V and 12.6V.

Anything below that (especially below 12V) means that your battery will struggle to start your engine. You need to change your battery.

How to correctly change your battery

When changing your battery there are a few things you need to check:

The group size

It defines the size of your battery. Not every battery can fit in the compartment of your car and you need to choose the proper group size. If you choose the wrong size, it won’t fit!

Cold Cramp Amps (CCA)

This is how many amps your battery can supply when it is very cold (zero degrees). So to be able to start your car in winter, you need to make sure you choose a battery with a CCA equal to or higher than what is recommended in the manual (or compared to the current battery).

To find the CCA, you can also check online to find what is the required CCA for your car.

AGM Batteries

One last thing, there is a recent technology called AGM batteries (Absorbent Glass Mat). 

AGM batteries are more resistant to vibration and offer better performance, minimal gassing and acid leakage when compared to conventional batteries.

So depending on your car, you may consider buying an AGM battery.

Replacing Your Battery The Right Way. 

Always disconnect the negative terminal at first. That will make it easier to then disconnect the positive terminal (red) and avoid any risk of bridging and sparking.

All batteries are held to avoid them moving and shaking while driving. So you need to find the tie-down and unscrew it.

Great!

Now you can safely remove your old battery and swap it with the new one.

You may have noticed that a battery is very heavy so be careful when lifting it up.

Now that the new one is installed, tie it down the same way as the old one.

Then install the plus side terminal (red) and then the ground side terminal (black).

Add some silicone grease to the terminal to prevent moisture and corrosion.

And now it is time for the moment of truth, turn on your car and check if it starts.

A quick note…

When your engine is running, it charges the battery through the alternator. So when you measure the voltage of the battery when the engine is running, it should read between 13.6V and 14.6V which means your alternator is properly charging your battery.

If it is less than that, it means you have an issue with your alternator which could explain why your battery was discharged in the first place!

Now keep in mind that more than 14.6V is not good either because your alternator is providing too much power to the battery which degrades it over time.

How To Avoid A Computer Reset When Replacing Your Battery

In some modern cars, if you disconnect the battery, the computer may lose some of its presets. You may then have some issues such as poor idling, acceleration, blocked radio, …

But there is a way to change the battery without disconnecting the computer.

To do so, you need to use jumper cables.

The idea is to have both the old and new batteries connected to your car at the same time so that you can then disconnect the old battery while keeping your new battery connected.

Use the jumper cable to connect at first the plus (red) terminal of the battery to the plus connector of the old battery. Connect it in a way that it will then be easy to plug the connector to your new battery while keeping the jumper cable on the connector.

Connect the black jumper cable to the negative side of the old battery. Connect the other side of the cable to a metallic part of the vehicle (ground)

Important, Make Some Cash With Your Old Battery…

After replacing your old battery, bring your old battery back to the place you bought the new one. Your old battery will be recycled in exchange for a few dollars!