Ultimate Car Battery Guide: How to Charge, Maintain, Replace, and more

If gas is the lifeblood of a car engine, the battery is the pulse that keeps it going. There’s no worse feeling than buckling up to drive somewhere and twisting your key in the ignition only to hear a clicking sound, and then silence. A boost may help jumpstart it again, but what if your battery has simply reached the end of its lifespan and needs to be replaced?

The good news is, it’s easy to keep tabs on your car’s battery life if you know what to look out for. We’ve compiled a few checklists and step-by-step guides to help you check, charge, boost, and replace your car battery.

How long do car batteries last?

Not everyone agrees on how long a car battery will last for. Conventional thought is about four years, but some people will tell you that up to six years is possible.

The lifespan of your battery depends on a number of factors:

• Canada’s harsher climate, with colder winters and hotter, humid summers mean the battery’s overall capacity could drop.
• Vibration is also an enemy of battery longevity, and you need to make sure your car’s battery is securely fastened under the hood with all the necessary brackets and bolts.
• Using in-car electronics can also tax the battery because so many features need power. Windshield wipers, headlights, heating/AC, car stereo, GPS navigation, backup cameras, and assisted driving functions, among others, all work off the battery.
• Voltage recharge rates can also play a role. Like fast smartphone charging where a large chunk recharges in a shorter time with the rest staggered out over a longer period, car batteries don’t hit 100% capacity automatically. For example, it may take seven hours to recharge up to 80-90%, and then take several hours to finish off the remaining 10-20%.

For that reason, shorter driving distances done frequently could actually reduce the long-term battery power sooner. This can also happen with “undercharging” caused by increased corrosion or leaving lights on overnight, for example. Constant undercharging leads to acid stratification, where the battery stays at a lower charge (below 80%) and never gets fully charged.

When should you replace a car battery?

It’s hard to truly gauge a battery’s health from the outside, but that doesn’t mean you can’t glean at least some insight into it. One of the telltale signs that something isn’t right is a slow crank. When you hear the car wheezing during ignition, especially when the weather isn’t cold, something might be amiss.

That may be caused by a weakened alternator not charging the battery fast enough, so it may not be the battery, specifically. But there are a couple of checks you can do that will help you determine whether you need a new battery soon or not.

How to check your car battery for damage

A good rule of thumb is to start inspecting the battery more frequently after three years. There are two checks you should do: an eye test and a load test.

1. The eye test

The eye test is simply a visual inspection when you lift the hood. Look for corrosion around the cell connectors or posts holding the battery, cracks on top of or down the side of the battery, a fraying or broken cable, or unusual stains. Any of these signs indicate your battery might need to be replaced soon. Also, a smell of sulfuric acid should not be ignored. This diagram highlights which parts of the battery should be checked during a visual inspection:

2. The load test

You can do a load test to gauge capacity and charge with a handheld multimeter (or voltmeter), which you can pick up at almost any hardware or automotive store:

1. Set the multimeter to 20 DC volts.
2. Lift the hood and match the prongs to the negative (black) and positive (red) terminals on the battery.
3. Push the start button. You don’t need to turn the car on yet.
4. What you’re looking for is a reading that maintains 9.6 volts. If it hits that mark and then steadily drops, that’s not a good sign. If it immediately drops to zero, that’s also a problem.
5. Turn on the engine and look for the measurement to hit 12.6 volts or so. If it’s lower than 12.2 volts or higher than 12.9 volts, then your battery either needs a slow charge or the removal of excess charge.
6. You can remove the excess charge by connecting your high beam headlights.
7. If your battery is undercharged, you can also trickle charge with an electric cord with a plug and two jumper cables with alligator clips to latch onto the negative and positive terminals. When it comes to long-term health, a slower charge benefits a battery more than a faster one does.

If it seems like your car battery is consistently losing its ability to hold a charge over time, it might be time to buy a new one.

How long does a car battery last without charging?

Picture yourself parked and waiting in the pick-up line, waiting for your kids after school. Since you can’t idle, you’re listening to the radio when you lose all power. The battery has died. 

It could be in various situations – waiting in line for a ferry, leaving the lights on, or leaving a charger plugged into the power outlet. How long will your car battery last without starting the engine to charge it? 

 The answer varies depending on several factors: 

• The age and condition of your battery
• Your battery’s style and design, including its reserve power
• The power demands from your accessories

A normal radio could play literally all day and your battery will still have the necessary power to start the engine, as is the case with most charging accessories inside. An amplified radio or a newer vehicle with a large infotainment screen might have only an hour or two in reserve. 

If you’ve left the lights on, how long your battery lasts depends heavily on whether it’s your headlights or interior lights, as well as if they’re normal halogen headlights or LED lights. It can range from just 30 minutes to several hours with headlights, and even days with the interior light left on.

If your battery dies after listening to the radio for less than an hour or a light left on kills the battery quickly, there’s a good chance it isn’t holding a full charge anymore and needs to be replaced.

How to jump-start a car battery (with booster cables)

Even if your car battery isn’t old, has no corrosion, and is securely connected and fastened, it may still die on you from time to time. There could be a number of reasons for this. Maybe you left the lights or car stereo on for too long while the engine was off. Or maybe the car sat inactive for too long.

If your battery problem isn’t actually a malfunctioning alternator, there are a few things you can do to jolt your car back to life. The first is a jumpstart with booster cables. You’ll need booster cables (obviously). You’ll also need a friend or helpful passerby to volunteer their car for your battery-boosting cause.

1. Make sure to park the functioning car close enough to the dead one so the cables can reach.
2. Connect the red or positive cable to the positive terminal on the dead battery, and then do the same on the other end with the working car’s battery
3. Connect the black or negative cable to the negative terminal on the working car’s battery, and then clamp the other end onto an unpainted metal surface, like the metal strut holding the hood open, or another exposed strut under the hood.
4. Start the working car’s engine and let it run for a few minutes. After that, try starting your car.
5. If the engine turns on, keep it running or drive around for about 15 minutes to let the alternator recharge it.
6. If your battery repeatedly dies on you, and there’s nothing wrong with your alternator, you might need to replace your battery.

How to revive a dead battery without booster cables

Besides getting a jump from another car, there are a couple of other ways to revive a dead battery. A battery charger is a handy device to keep on hand when you don’t have booster cables or another vehicle to draw power from.

1. Using an automotive battery charger

An automotive battery charger connects to your battery in the same way jumper cables do. Simply connect the red clamp to the positive terminal, and then the black clamp to the negative one. Plug in the battery charger to a power outlet. Chargers can also retain a charge with their own battery, letting you use them on the go as well.

These videos by caranddriver.com are a great reference on how to charge your car battery with a battery charger.

Step 1: Lift the hood of your car and uncase your battery's terminals.

Step 2: The red clamp attaches to the battery's positive terminal and the black clamp attaches to the negative terminal. After you connect to the terminals, plug your charger in and turn it on.

Step 3: When your battery is charged, disconnect the charger by removing the black clamp first and then the red clamp.

Video Credit: caranddriver.com

2. How to push-start a car with a dead battery (aka bump start)

If you don’t have any booster cables or a battery charger, a couple of willing friends will help you push-start your car. The faster your friends can push the car above 8km/h (with you in the driver's seat), the more likely the engine will start when you depress the clutch and switch the ignition on. Here's a great youtube video by howcast.com on how to do this:

How to make your car battery last longer

Car batteries can be expected to need replacement eventually, and a high-quality battery to fit your vehicle isn’t always inexpensive. But there are things you can do to make it last as long as possible. 

• Don’t let it become completely discharged. Letting your battery fully discharge is sure to take away from its normal life expectancy.
• Remove your car battery when it’s in storage. If you don’t plan to drive your car for at least two weeks, disconnect the battery to prevent normal draws from killing the charge. Or, put it on a trickle charger until you’re going to use your car again. 
• Service your battery annually. That includes cleaning corrosion from the terminals, checking and topping up the battery electrolyte fluid if necessary, and charging the battery to full capacity.
• Make sure your battery is securely clamped down to prevent damaging vibrations.

How to replace the battery

After you’ve determined that your vehicle battery is ready for retirement, the following steps will help you swap out your car battery by yourself:

1. Make sure the vehicle is off and the parking brake is applied.
2. With your smartphone, take a photo of the battery compartment before you remove it. Having a photo will help you remember exactly how to reconnect the new battery.
3. Disconnect the black (negative) cable first. Then, disconnect the red cable.
4. Use a wrench to remove the battery restraint, sometimes laid out as a bar on top or clip holding it in place at the bottom.
5. Remove the battery, and keep it steady without tilting it when lifting it up.
6. Install the new battery by reversing the uninstallation steps.

Properly dispose of the old lead-acid battery by taking it to a store that sells new car batteries, like Canadian Tire, Costco, Walmart and other auto parts locations. There is no municipal recycling pickup for used car batteries.

Do you need to charge a new battery before use?

When you buy a car battery, it typically comes sufficiently charged to start your vehicle, to around 90% of capacity or so. It isn’t required to charge a car battery before its first use. 

However, under normal driving conditions, the alternator is unlikely to charge your battery to full capacity. It keeps it sufficiently charged, but fully charging a new battery if you have the time to do so will ensure you get the best life expectancy from your new car battery.

How much does it cost to replace a car battery?

Car batteries range in price from under $100 to over $400. You can find them at various retailers, like Canadian Tire, Costco, Walmart and auto parts stores. Be sure to have your car’s make, model, engine size, and battery dimensions handy when picking one up.