How Far Do I Need to Drive to Charge My Car Battery?

Car batteries provide the massive jolt of electricity needed to start your vehicle’s engine. Once that’s accomplished, your vehicle’s alternator works to recharge the battery while you drive. One thing many people fail to realize is that recharging a battery takes time. If you don’t drive your vehicle long enough or often enough, your battery’s charge will continue to get lower and lower each time you start the engine. So, how long do you need to drive your car to recharge the battery? Does your driving speed affect how fast your battery recharges? Keeping reading for answers to these and other commonly asked car battery questions.

How Many Volts in a Fully Charged Car Battery?

Most modern vehicles have a 12 volt battery underneath the hood. A 12 volt car battery contains six cells, each of which will contain 2.1 volts of power when fully charged. So, when the engine is off, a car battery is considered fully charged at 12.4 to 12.6 volts.

When your battery’s voltage drops even a small amount it can make a big difference in its overall performance. For instance, a voltage of 12.1 volts means your battery is operating at only 50% of its total charge. Once it drops down to 11.6 volts, the battery is almost completely discharged.

How Much Driving to Fully Charge a Battery?

You need a minimum of 1000 revolutions per minute (RPM) from your engine to generate the power needed to charge your battery. Faster speeds generate more RPMs, so your battery will recharge faster at speeds of 55 MPH or higher. It takes most vehicles about 30 minutes of driving at highway speeds to fully recharge the battery. Keep in mind that 30 minutes is an average. If your battery is severely discharged, it may take even longer to recharge it.

Do Car Batteries Charge While Idling?

A car with an idling engine will still recharge your battery, but at a much lower rate than if you were driving. The reason for this is that modern cars have a lot of additional electronics that use up power. Guess which component is responsible for powering these additional systems? That’s right, it’s your alternator. If your car is just sitting there idling, it’s not generating a lot of RPMs, meaning it will take your battery much longer to recharge this way. How long? We’re talking several hours. Your best bet is to just take your car for a spin instead of leaving it idling in your driveway.

How Long Does a Car Battery Last without Driving?

An idle battery can go from fully charged to completely dead in a little under two months. Your battery will die even faster if it’s older than three years or wasn’t fully charged the last time you drove it. One thing that’s not good for your battery is taking a lot of short driving trips in a row. There’s nothing wrong with tackling a bunch of errands, but if you’re constantly starting and stopping your engine with only a few minutes of driving in between, it will drain your battery pretty quickly. Try to take a 30 minute drive on the highway at least once a week to give your alternator the time it needs to fully recharge your battery. Find more tips on how to keep a car battery from dying when not in use.

What are the Different Types of Battery Chargers?

So what do you do if you have a car that you don’t typically drive all that often? Your best bet is to pick up a battery charger. A battery charger will help keep your battery charged up and healthy so that it’s ready to go. When shopping for a battery charger, you’ll want to follow two basic rules. Rule number one: the charger you select must be compatible with your battery’s chemistry. So what do we mean by chemistry? For a lead acid battery, you’ll need to find a lead acid charger. If you have an AGM battery in your vehicle, you’ll need a charger that is AGM compatible. Many modern battery chargers have different settings that enable them to charge batteries with different chemistries.

Rule number two, the voltage of your charger must match the output voltage of your battery. So, for a 12 volt car battery, you need to get your hands on a 12 volt charger. If you have a truck that uses a 24 volt battery, be sure that you get a 24 volt charger. It’s important that you follow both of these rules. Charging a battery with the wrong charger can permanently damage your vehicle’s battery.

Another thing to keep in mind is that there are three different types of battery chargers: standard chargers, trickle chargers and battery maintainers, each of which works a bit differently. Learn the difference between these three types of chargers in our blog entitled, "When Should You Use a Battery Maintainer?"

How Do You Know When Your Battery Needs to Be Replaced?

No matter how well you care for your battery, eventually it will have to be replaced. Car batteries typically last between three and five years. There are a number of symptoms that will help tell you when your battery is dying. Aging car batteries often have a hard time holding a charge, so if your battery struggles to start up your engine, that’s a good sign it might be going. If you find yourself having to jump start your engine on a regular basis, that’s another good sign that your battery needs to be replaced.

Have Your Battery Tested for Free at Batteries Plus

Not sure if your battery is still good? Bring it to your nearest Batteries Plus for a free test. We’ll test your battery’s Cold Cranking Amps and voltage, as well as your vehicle’s starter and alternator. If you need a new battery, we have plenty of replacement car batteries available. Plus, we offer free installation on most makes and models at most of our locations. Looking for more troubleshooting tips? Our blog entitled "6 Reasons Your Car Battery Isn’t Working" has plenty of useful information.