For as important as it is, you probably don’t spend much time thinking about your car battery—that is, until it dies. Once your battery is dead, a jump can start your car, but you’ll need more than that to fill it up again. Believe me, knowing how long does it take to charge a car battery is really important.
So how long does it take to charge a dead car battery? The answer can vary, anywhere from about 30 minutes to as long as 24 hours. Mostly this depends on what method you use to charge it.
There are two main methods for charging a car battery: using a dedicated battery charger or simply by driving your car. We’ll go more into both in detail below.
Why Should You Know How Long Does It Take to Charge a Car Battery?
There are a couple of answers to this. First of all, if your battery is dead you need to know how long it’ll take to refill it enough for starting your car. Charge it too little, and you could end up stranded again and in need of a jump.
On the other hand, though, you shouldn’t just charge your battery all the time. Overcharging can damage a car battery by deteriorating the electrolyte mix inside. Batteries also heat up when they overcharge, and these high temperatures damage the battery even further.
Many battery maintainers and chargers have auto-shutoff settings that prevent overcharging. In this case, there’s no danger of leaving your battery on the charger for too long. If your device doesn’t have this protection, however, you should pay close attention to the timing if you want to avoid further damage to your battery.
How Long Does it Take To Charge a Car Battery While Driving?
Charging while driving is the safest way to recharge your battery, period. When you drive, power from the engine is sent into the battery through the alternator until it’s full. Once it is, that power will be used elsewhere in the engine, instead, so there’s no risk of overcharging.
Using your car to charge your battery is also a whole lot faster than using an external charger. You can get the battery charged up enough to at least start your car in about 30 minutes. Even fully charging the battery can sometimes be accomplished in around an hour.
The higher the revolutions per minute (RPM) of your engine, the faster the battery will charge. At the minimum, you’ll need to get your car’s engine going faster than 1,000 RPM to generate enough extra power for charging the battery.
Faster speeds generate more RPM. If you’re looking to charge your battery, get to a highway or other long, open road where you can reach at least 55 miles an hour for a sustained period. Your battery can charge driving at city speeds, but it will take longer.
Another thing that will help is to turn off all components powered by the battery. Drive during the day so you can turn off the headlights. Also, turn off the radio, and avoid using charging ports or other electronic components.
If your car doesn’t seem to be charging your battery effectively, there are two likely culprits. One possibility is that the battery is old or worn out. Most batteries last between 5 and 7 years from the date printed on the label. Deep discharges and high temperatures can shorten its lifespan, however.
The other possibility is that your alternator is failing. This can be a very costly repair, however, so you should definitely test your battery before assuming it’s the problem.
How Long Does it Take to Charge a Car Battery with a Trickle Charger?
To fully charge a dead battery using a trickle charger, you’ll need to leave it sitting for quite a while. The exact time depends on how many amps the charger sends at any given time.
Fast charging devices can fully charge a dead battery in as little as 10 hours. Other models may take as long as 24 hours get back to full capacity. If you just want to get the battery charged up enough to start your car, you’ll need around 2-4 hours on average.
Be careful to strike a balance between speed and safety when using a battery charger. You can find chargers rated as high as 40 amps. These models will charge your battery faster, but they also put you at risk of overcharging. If you leave the battery unattended, you could inadvertently damage or even destroy it.
Lower-powered chargers take longer, but they’re less likely to cause damage. You may want to look for a charger with smart or auto settings. These send variable amounts of power to the battery based on its current capacity. This speeds up the charge but also means you won’t have to hover over the battery while it’s charging.
The best use of a trickle charger is to maintain a battery that you don’t use often. In this case, how long the battery takes to charge isn’t a concern, as long as you make sure it’s charged the day you plan to use it.
The Last Word
How long does it take a car battery to charge? Now that we’ve gone through all the details, you see the answer to that question isn’t always simple. It depends on how depleted the battery is and what method you’re using to charge it.
If you drive your car every day, your battery should naturally stay charged up enough to start your car. For vehicles that sit a week or more at a time, you may want to invest in a trickle charger. Of course, there is also the case of needing to recondition your battery!
The best way to keep your battery healthy is to make sure it’s fully charged all the time. Whether you accomplish this by driving frequently or through the use of a maintainer or trickle charger is up to you. Just follow the advice above and your battery will always be charged and ready when you need it!