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You, your mom, your auntie, your third cousin, and your future child likely have or will have to replace a car battery at least once—even if we live in space. It’s a part of life as an automobile owner, and unless you’re a city rat who relies solely on public transportation, it’s an issue that arises every few years.
But how many years is the correct amount of time between replacing a battery? It’s not like this is a AA that dies after a week’s worth of Pokemon Blue on the Gameboy Color. The typical 12-volt car battery is more complex than you might think, and its health is affected by numerous factors.
Read The Drive’s detailed Garage Guide To Battery Life as we discuss positive terminals, electrolytes, and acid and answer the question, how long does a car battery last?
How Does A Car Battery Work?
According to battery manufacturer Optima Batteries, a battery is, “one or more galvanic (electrochemical) cells electrically coupled into a single unit and equipped with attachments for external electrical connections.”
There are numerous types of car batteries available today. Below, we discuss what they are and how they work.
Flooded Lead-Acid
Flooded lead-acid batteries are the most commonly used type of battery in consumer vehicles. A standard lead-acid battery consists of lead and lead oxide plates submerged in an electrolyte, a solution made of 35 percent sulfuric acid and 65 percent water. Each battery has six cells, each of which has positive and negative plates inside, lined up in series and two terminals, positive and negative. The negative terminal acts as the anode, while the positive terminal acts as the cathode. Long story short, the acid reacts with the lead (anode) and lead oxide (cathode) and gets the energy flowing once the cycle is closed with the battery cables. The anode releases electrons while the cathode uses them.
Within a car’s battery system, the alternator charges the battery, and without it, the battery will discharge until it’s dead and can no longer perform its primary functions.
Gel
Gel batteries are generally similar to regular lead-acid batteries, but they feature gel added to the electrolyte. This helps prevent movement inside the battery.
Absorbed Glass Mat (AGM)
Certain companies such as Optima sell sealed AGM batteries. AGM stands for Absorbed (or Absorbent) Glass Mat, and this type of battery holds and suspends the electrolyte like a sponge while maintaining contact with the active lead material on the plates. AGM batteries are also designed not to spill, sulfate, or degrade and are shock-resistant. Additional benefits of AGM batteries include more efficient discharging and recharging, higher starting power, and longer service life.
What Does a Car Battery Do?
The primary functions of a car battery are to power the starter to start the car, to store energy, and to provide electricity throughout the vehicle to accessories such as the lights and the radio.
How Long Does a Car Battery Last?
Average 12V car batteries typically last three to five years, and manufacturers recommend always replacing car batteries once those five years are up.
Factors That Affect Battery Life
Keep these factors in mind when considering your battery life.
- Time
- Temperature
- Driving style
- Condition of the charging system, including the alternator
- Regular car maintenance
What Does the Dashboard Battery Light Mean?
For more on this topic, read The Drive’s guide, Why is Your Battery Light On and What Does It Mean?
Symptoms of a Bad Battery
If you notice one or more of these symptoms, it might be time to get a new battery.
- Car won’t start
- Car rapidly clicks and won’t start
- Rough start or slow crank
- Dim headlights
- Backfiring
How To Test a Battery
There are two ways to test a battery.
- Test the battery with a car battery tester. This allows you to also test the battery under load.
- Use a multimeter to test the battery for the correct voltage. A fully charged battery should register 12.6 volts or more. If it’s off, try recharging the battery with a trickle charger before replacing it.
How To Charge a Car Battery
- Park the vehicle out of the way with a clear path between the plug and the vehicle. Be careful not to place wires in the way of foot traffic.
- Turn the car off, pop the hood, and find the battery.
- Disconnect the battery terminals, negative first, and place them out of the way, separate from each other.
- With the charger plugged in and in the off position, connect the positive clamp to the positive terminal. Look for red caps and/or a “+” symbol.
- Connect the negative clamp to the negative terminal. Look for the black cap and/or a “-” symbol.
- Turn the charger on and set it to 12V.
- Charge the car for as long as necessary.
- Turn the charger off and remove the cables in reverse order.
- Using a multimeter, once again check the voltage of the battery. It should read 12.6 volts or above when the car is off and between 13.7-14.7 volts when the car is running.
- If the battery does not recharge, replace it.
The Drive’s Garage Guide To Changing a Bad Car Battery
Let’s do this!
Basics
Estimated Time Needed: 30 minutes
Skill Level: Beginner
Vehicle System: Charging
Battery Safety
Working on your car can be dangerous and messy. Here’s what you’ll need to ensure you leave the garage in the same condition you entered.
- Non-conductive mechanics gloves
- Safety glasses
- Face mask (optional)
Everything You’ll Need To Change a Car Battery
Preparation for the job is key, so gather these tools and get them in order before you start.
Tool List
- Wrenches or socket set
- Phillips and flathead screwdriver, if necessary
- Wire brush and baking soda cleaning solution, if necessary
- OBD ECU memory saver, if necessary
Parts List
How To Change a Car Battery
Let’s get into it.
- With a cooled-down car on a level surface, pop the hood. The latch is usually underneath the dashboard on the driver’s side. If you cannot find the latch, consult your owner’s manual.
- If you have a newer vehicle, this is the time to plug in an OBD ECU memory saver. These cheap devices will prevent ECUs from resetting and losing any previously stored settings while the battery is removed.
- Locate the battery and use the wire brush to clean as necessary.
- Remove the brace or bracket that holds the battery in place.
- Depending on the design, loosen or undo the fastener, clamp, or connector on the negative terminal (typically the black one with the “-” negative or minus symbol) and remove it.
- Undo the connector on the positive terminal (typically the red one with the “+” positive or plus symbol.
- Remove the battery. Be careful with its heavy weight.
- Clean the battery terminals, if necessary.
- Insert the new battery.
- Reattach and tighten the positive terminal.
- Reattach and tighten the negative terminal.
- Attach the brace or bracket that holds the battery in place.
That’s it, well done!
Get Help Replacing Your Car Battery From a Mechanic On JustAnswer
The Drive recognizes that while our How-To guides are detailed and easily followed, a rusty bolt, an engine component not in the correct position, or oil leaking everywhere can derail a project. That’s why we’ve partnered with JustAnswer, which connects you to certified mechanics around the globe, to get you through even the toughest jobs.
So if you have a question or are stuck, click here and talk to a mechanic near you.
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Energizer Jumper Battery Cables
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Got a question? Got a pro tip? Send us a note: guidesandgear@thedrive.com
