Finding yourself stranded with a dead vehicle battery caren be a nightmare. Perhaps you left your headlights on while at the store, or maybe your vehicle was in accessory mode for a little too long. Whatever the case, after jumpstarting your vehicle, you’re likely wondering how long it’ll take to charge a dead car battery. We’re here to satisfy your curiosity.
After jumpstarting your vehicle, you can go ahead and let the engine run. Keep the engine running for at least 30 minutes. Driving a car does charge the battery. The point is to let the engine run so the alternator stays on. The alternator is what recharges a car battery, and it’s connected to the engine crankshaft via a belt. So as long as your vehicle’s engine is running and there’s nothing wrong with the alternator or the battery, your vehicle’s battery is charging. It should take 30 minutes to sufficiently charge your vehicle’s battery.
It’s also best to drive your vehicle around rather than letting it sit idle. Modern vehicle systems have battery-saving measures that might limit your vehicle’s ability to charge at lower RPMs. Driving at higher speeds should increase your vehicle’s battery charge faster.
This is, of course, only for regular vehicles. If your electric vehicle (EV) runs out of charge, you need to bring it to the nearest charging station.
Fully charging your EV battery can take as fast as 30 minutes or less if it has a typical 60 kilowatt-hour (kWh) battery and you’re using a 150 kilowatt (kW) rapid charging station. Using a 7kW charger will take 8 hours, and a 22kW charger will take 3 hours. Some slower home chargers at 3.7kW will take 16 hours to fully charge a 60kWh battery.
If your vehicle’s alternator isn’t keeping your vehicle fully charged, you might need to rely on an external car battery charger to top it up. It’ll take four to eight hours of charging to fully charge a normal vehicle battery with a smart or automatic vehicle battery charger. These chargers provide slow charging with relatively high voltage. It’ll take days to fully charge a battery with a trickle charger. Trickle chargers are mainly for topping up the batteries in vehicles you don’t use often, so if you’re in a hurry, they aren’t ideal.
That being said, if you’re resorting to an external battery charger instead of your vehicle’s alternator, there’s likely something wrong with the alternator, the battery, or the vehicle’s electrical system. Bring the vehicle to a trusted mechanic so they can diagnose and address the issue.
Amps measure how much electricity flows through either a circuit or a wire. Essentially, they represent how strong the electric flow is. For car battery chargers, amps measure how quickly electricity moves from the charger to the battery. The higher the amps, the faster the power is flowing into your battery, the lower the charging time. Here’s a breakdown of amp chargers and how long they take to charge an EV battery:
Remember that the higher the amps, the faster the charge. The 50-amp chargers pose a significant overheating risk because of how quickly they can charge and overheat a battery. It’s safer to stick to the reliable lower-amp chargers.
There are quite a few things that affect battery charging speed for both regular vehicle batteries and EV batteries.
Typically, a battery’s capacity indicates how much charge it can hold. The higher the capacity, the more charge. In both electric vehicles and normal vehicles, larger batteries with higher capacities will naturally take longer to charge. You can typically find your vehicle’s battery specifications in the owner’s manual or manufacturer handbook.
Most regular vehicle batteries are lead acid batteries which take 30 minutes to charge using an alternator and 8 to 10 hours on an external charger. Some regular vehicles also use lithium-ion batteries, which charge much faster. Unfortunately, many lithium-ion batteries in regular vehicles experience battery drain quicker than their lead acid counterparts.
Electric vehicles typically use solid-state batteries. Manufacturers and researchers are currently developing faster-charging EV batteries though, and other EV battery types with different charging capabilities are beginning to emerge. A lithium-ion EV battery that charges in under five minutes is currently under development.
Whether it’s an EV battery or a regular car battery, your vehicle’s battery has a service life. An older battery won’t be able to hold as much charge as a new one, and this can affect charging speed. Normal vehicle batteries will last around three to five years. EV batteries have a longer lifespan of 10 to 20 years, but they’re also significantly more expensive.
Also, if the battery’s damaged or in bad shape, it might not be able to charge as fast as it usually would.
We’ve already touched on how amp charging rates affect EVs. The more amps an EV charger can handle, the faster the EV battery charges. Likewise, higher-kilowatt chargers will also speed up EV charging rates.
The same can’t exactly apply to normal vehicle battery charge rates. Typical vehicle batteries have maximum charging rates. If you plan to charge a normal vehicle battery with an external charger, its maximum current shouldn’t exceed 20 to 25% of the battery’s capacity. This limits how fast the battery can charge safely.
Cold weather affects both EV and regular vehicle batteries. When operating at low temperatures, vehicle battery capacities go down. That’s why it takes longer to charge in winter than in summer. That being said, extreme heat can also slow down charging times.
EV batteries tend to charge slower after they reach 80% capacity. This is because batteries tend to absorb energy more slowly as their charge increases. Oddly enough, it’s better for your EV battery to stay below 100% if possible, so you might want to enjoy fast charging to 80% and leaving the charging station after instead of waiting much longer for the final 20% top-up.
If you’re looking to charge your regular vehicle’s battery with an external charger, here are some options you can buy off the shelf:
In the end, how long it takes to charge a car battery depends on many different factors that we hope you enjoyed reading about. Keep these battery-charge-time facts in your head in case you ever find yourself stranded and wonder how long to leave your engine running.
Any information provided on this Website is for informational purposes only and is not intended to replace consultation with a professional mechanic. The accuracy and timeliness of the information may change from the time of publication.