A badly corroded battery.

Car Battery Maintenance Basics

First thing in the morning, you leave the house thinking about work, bills, kids, whatever. You get in your car, put the key in the ignition, turn the key, and… Nothing. Or maybe the engine turns over painfully slow, then stops all together. Or maybe it just makes a really loud click.

Now what?

It’s possible that your battery needs to be charged or replaced. An auto battery replacement is an easy job the average driver can safely do themselves.

*First- a note about safety when working with a car battery.

Gloves and protective eyewear should be worn when working on batteries.

Automotive electricity generally won’t kill you, but it will hurt and can cause burns, so use caution and consult a quality repair manual before working on your cars electrical system.

Typically, car batteries will show a plus-sign on one post and a negative-sign on the other to indicate direction of current. Negative is typically a black wire and is called ground or earth. Ground will run from the battery to a place on the frame or engine. Positive will run to a solenoid or a junction point with many other wires connecting to it. Consult a repair manual if you are not sure.

Do not reverse the battery cables. Installing a battery backward, negative to positive, can damage vehicle electronics, destroy the battery and even cause fires and explosions.

A basic diagram of a vehicle starting and charging system.

When removing battery cables, always remove the negative cable first and ensure the terminal end is not touching metal or any part of the car before removing the positive. This prevents the electricity in the circuit from being able to shock you.

Batteries store power through an electrical process that involves plates of lead, liquid, electrical current and sulphuric acid. Sulphuric acid will cause severe burns to skin, eyes and airways when it comes in contact with them.

Most automotive repair stores will sell a packaged battery cleaner, but an effective home recipe is to mix a tablespoon or two of baking soda with enough water to make a thin paste. Use a rag and wipe down the surfaces of the battery. The baking soda will neutralize any acid present.

Do not put auto batteries in the trash.

Make sure the key is not in the ignition before working on your car battery. You should not try to work on a battery while the car is running. Be careful when lifting a battery as they are heavy.

Why won’t my car start?

Most automotive batteries will last for five to seven years, reliably, with very little service. In the old days, batteries had to be regularly checked to ensure the water level was high enough and a special tool called a hydrometer was used to make sure the electrolyte level was correct. Most batteries today are maintenance-free, and will have an “eye” that does the job a hydrometer used to do. Green means it’s good.

Car batteries cannot be rebuilt and when they fail, it might be time for a car battery replacement. Automotive batteries today can cost more than $200 US, and unfortunately, without a battery, your beautiful car is not much more than a garage ornament. There are some steps to take before declaring your car battery DOA, and you may not need an auto battery replacement just yet.

Look at your battery. In older cars, the battery is under the hood, on either the right or left side. More modern cars may have the battery in the trunk, behind the seat, or even under the spare tire. A workshop manual will show you where your battery is located if you are not sure.

The most common sign that a battery is in distress is the presence of corrosion on battery terminals. Typically, corrosion will look white or chalky and will collect around the posts and around service caps on older batteries. It may even be blue-green if the corrosion is particularly bad. A leak from a maintenance-free battery is usually an indicator that your car battery life is up and you will need an auto battery replacement.


A badly corroded battery.

Corrosion can cause a battery to discharge electricity rapidly, but it is an easy fix. Regularly inspecting your battery for corrosion is a great preventative step to avoid breakdowns.

If you see corrosion on your battery terminals, you will need to disconnect the cables and clean the terminals.

Maintaining a Car Battery

Car batteries are either top-post or side-post. Usually, top-post battery cables will require a 1/2” wrench to remove. Side-post batteries are typically secured with a 10 mm bolt. Once loose, twist the clamp gently, rocking it side to side. Never pry a terminal clamp off with a screwdriver as this can cause damage to the battery posts and covers, ruining a battery and creating a dangerous acid spill.

Batteries are usually held in place with a bracket that crosses over the top of the battery and will need to be removed in order to get the battery out. Older vehicles sometimes use batteries that have “feet” with a plate that clamps down against the bottom of the battery to hold it in place.

Most automotive repair stores will sell a battery post cleaner. This is usually a metal, two piece tool that has metal bristles inside the bottom and outside on the top. Clean the post with the bottom and use the top to clean the battery cable clamps. Automotive repair stores sell a type of grease that can inhibit corrosion and promote a good connection.

Sometimes, cleaning battery terminals will provide a better connection and allow a car to start.

Car Battery Chargers

A battery charger is far better than jump starting a vehicle. Some modern vehicles have specific methods of jump starting, and incorrectly connecting to the system can cause serious damage.

Car battery chargers come in all sizes and shapes, but all function the same. They will plug into a 110 v socket (a wall socket) and have color-coded clamps, one red for positive, one black for ground. Connect the clamps to the corresponding battery terminals, then plug the charger in to the wall circuit.

Most allow two or more types of charging. Typically, a low-amperage charge is recommended. Lower amperage causes less heat, which damages batteries, but takes longer to charge. Some chargers will have a “start” function.

Portable automotive jump starters are often called boost-boxes and jumper-boxes. The start setting should be used with caution and only when necessary. A portable jump starter can help start your car even when your battery is no good.

A portable car battery jump starter is used to jump start a weak battery.

Many owners who have cars that are not frequently driven will use a type of constant battery charger, called a battery tender. These will keep a battery at a good voltage without overheating the battery. Solar versions of battery tenders are popular.

Most automotive parts stores can recharge and test a dead battery for you, but you will need to remove the battery from the car and take it to the shop. There typically is no cost for this service.

When you buy an auto replacement battery, the salesperson can tell you about places that buy auto batteries. Typically, the place you buy your battery from will take your old battery. Recycling centers are places that buy car batteries, but not all do, so call first.

If you are able to drive your car to a shop or repair store, they will typically install your new battery for free. Most of the time, there is no car battery installation cost.

Installation is easy yourself. Just hook the cables up, reattach the battery hold down, and make sure you didn’t leave any tools laying around.

It is a good idea to look at your battery at least once per year and inspect the wires around the battery while you are at it. Cracking, burned wires, corrosion, or frayed wires should be replaced. A parts catalogue will list the right cables for your car.

Extend the life of your car battery.


About Derek F


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