How to Test & When to Replace a Dead Car Battery


There are few things more frustrating than sitting behind the wheel of your car, ready to go somewhere, only to find that your car’s battery is dead. But why is your car battery dead and what can you do to fix it? Let’s take a closer look at what can cause your vehicle’s battery to malfunction, how to jumpstart a dead car battery, and car battery replacement.


Possible Causes of a Dead Car Battery

The most obvious case of a dead car battery is simple user error. Either you’ve inadvertently left an overhead light on, left something charging in the accessory power source, or used too much accessory power when you’ve only driven a short amount. That means a lot of your battery’s power was used when you started your vehicle, but your alternator — which returns power to your battery — didn’t have enough time to fully juice your battery up.

Another potential cause of a dead car battery is age. Most car batteries utilize lead-acid, multi-cell batteries. Each cell is filled with a dilute solution of sulfuric acid as well as lead. As your vehicle’s battery ages, it undergoes a natural process called sulfation. This is when the negative plates in your car’s battery are coated in sulfate crystals, which can then build up and reduce your battery’s ability to deliver power to your vehicle and prevent your car from starting. If your car’s battery is between 2-5 years old, this could be the culprit and it might be time for a replacement.

On occasion, a dead battery could be caused by a defect in your automobile’s battery itself. If you are repeatedly experiencing a dead battery and your vehicle or battery is new, it might be worth bringing your car into the shop to have a mechanic run a battery test to determine if it has some sort of internal defect.

At times, a dead car battery might not be indicative of a problem with the battery, per se, but rather your car’s charging system. If the battery warning icon comes on while you’re driving, this is likely a sign that there’s a malfunction within your charging system and you should have a mechanic check to see if your alternator, serpentine belt, battery cable and terminals, and alternator belt are all functioning properly.

Finally, a dead car battery could be indicative of corrosion on your battery terminals. These are the posts that connect your battery to the rest of the charging system. At times, corrosion — which looks like white, ashy deposits — builds up between the terminal posts and the battery cables and can cause a reduction in flow of power in your vehicle. You can use a wire brush and baking soda to remove corrosion from your battery, however, if it keeps occurring, this might suggest that either your battery, battery cables, or terminals need to be replaced.


The Ten Steps of Charging a Car Battery

If you find yourself suddenly stranded with a dead car battery, your best bet is to jump start it using another car’s battery. Luckily, if you can locate some jumper cables and a willing Good Samaritan, charging a car battery is fairly simple. Here are some simple steps and tips for properly charging your vehicle’s battery.

1.) Check jumper cables

Make certain that your jumper cables are clean, the alligator clips are free of erosion, and that there aren’t any tears or kinks in the wires.


2.) Turn off engines on both cars

Make certain that you’re both in Park and that the ignitions are fully disengaged.


3.) Attach red alligator clip to the positive terminal of the dead battery

The positive terminal will be marked with a plus symbol. A simple mnemonic device that will help you remember that red is attached to the positive terminal is to think about the sun and how its heat is positive energy while space and its blackness is negative energy.


4.) Attach the other red clip on the other vehicle’s terminal

Attach one of the black clips to the negative terminal of the other vehicle. The negative terminal is marked with a minus symbol.


5.) Attach the final black alligator clip to your vehicle body

Instead of attaching the clip to the negative terminal of your battery, you’ll want to find an unpainted metal surface — such as the body of the car or the metal rod that props open your hood — which isn’t near the battery. This is to help ground the electrical flow and prevent sparking from the battery.


6.) It’s important to remember to do this in the correct order

You, Them, Them, You.


7.) Start engine

Start the car with the good battery first and allow it to run for a few minutes. Then you can try starting your own vehicle. If it doesn’t start at first, check your connections and allow for more time for power to flow between the batteries.


8.) Let your vehicle run

Once you get your car restarted, it’s important to remember that your battery will still be low on power. Give it 15-30 minutes of running, preferably at highway speeds without using peripheral devices that drain the battery like radio.


9.) Look for problems

If you repeatedly find your car’s battery is dead, and you can’t identify any user error like an overhead light left on, you’ll likely want to consider car battery replacement.


When to Consider Car Battery Replacement

As stated above, if you consistently find that your battery is dying, that can be a clear sign of a problem and you may want to replace your battery. But are there ways to identify a failing battery before you find yourself stranded somewhere? The answer is sometimes.

As your battery ages, it loses its capacity to hold an electrical charge. This can result in some identifiable issues, especially when you’re starting your car. Look for the sound of a lazy engine — meaning it takes longer to turn over when you’re starting your vehicle — or flickering overhead lights when you’re starting up your vehicle. If you hear or notice them, that’s a good sign that your battery is weakening and that it may be time for a new one. You could also consider bringing your car into the mechanic’s shop or a car dealership to have the battery levels tested for a definitive answer.


How to choose the right car battery

As the most important part of your vehicle’s electrical system, it’s important to know what you’re looking for when it’s time to replace your battery. But it can be confusing. So, what should you look for? First, you want to be certain that you’re choosing a battery that will be powerful enough — but not too powerful — for your vehicle. Consult your owner’s manual and see what it suggests is the right number of cranking amps — the amount of power that’s required to turn over your vehicle’s engine — and choose a battery that fits within those parameters.

Second, you may need to take into consideration cold cranking amps, or the amount of power it takes to turn over the engine in freezing temperatures, especially if you live in a colder climate. It can make the difference between your car starting on a cold winter’s day.

Finally, you’ll need to decide whether a maintenance-required or a maintenance-free battery is the best option for you. While a maintenance-required car battery, which requires regular electrolyte monitoring and top-offs, are cheaper on the front-end, maintenance-free are a lot more hassle-free and don’t require much attention. Make certain you’re ready for the commitment if you decide to save money and go for the cheaper option.


How to put a new car battery in your car

While you could always have your battery replaced in the shop, it’s something you can do at home, too. If you decide to go the DIY route, there are a few things that you’ll want to keep in mind. First, always check your owner’s manual for any safety precautions that might be listed. Second, always wear gloves as battery acid can be quite harmful to the skin. Third, always disconnect your battery’s negative terminal before the positive. Fourth, never touch a metal tool to the battery posts or terminals. Finally, be cautious of sparking both from the battery and around the battery and always wear eye protection as a precaution. With that in mind, here’s how you change a battery:

1.) Make certain your engine isn’t running

Using a wrench or special battery pliers, detach the negative cable — it’s black — from the battery by loosening the nut. If there’s a lot of corrosion that makes this difficult, you can clean it away with a solution of baking soda and water.


2.) Remove the cable by twisting and pulling gently

You can also use a tool called a battery terminal puller — found affordably at an auto parts store — to help pull it up and off. Use caution because you don’t want to break your battery terminal.


3.) Repeat on the positive — or red — battery terminal


4.) Remove the battery clamp

The battery clamp is holding the battery in place, by unscrewing it with a wrench or socket and then moving it out of the way.


5.) Remove the battery


6.) Clean up any corrosion or residue

Clean the tray or on the battery posts and battery connector with a baking soda water solution and a clean cloth or wire brush. If there’s too much corrosion and deposits, you may need to utilize a battery cleaning solution.


7.) Position the new battery in the battery tray

Re-clamp the battery into place.


8.) Attach and tighten the terminal into place

Beginning with the positive cable


9.) Repeat with the black cable


10.) Double check all connections


You want to be sure that the terminals are tight against the posts for a good connection. If you can wiggle the cables at all, tighten them more.

Finally, because car batteries are so acidic, they can’t simply be thrown away. Instead, you’ll need to recycle your battery properly. Most auto shops and auto parts stores, as well as many car dealerships, offer free battery recycling. Just give them a call first to check.



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