Posted: Feb 28, 2018
How Long Does a Car Last After a Jump Start?
How long does a car last after it receives a jump-start because the battery is too discharged to start the car? It's a question often asked and we've read some absolutely terrible advice, such as driving a car for 10-15 minutes, which is not a good idea. We want to set the record straight and we decided to use one of our own employee cars as an example. OPTIMA Jim picked up his brand-new 2013 Ford Flex on February 21, 2013. Nearly five years to the day- February 27, 2018, he received a call from his wife about the car. She was at a park and the car wouldn't start.
Jim knew what the issue was- the battery. The battery in the Flex was the original battery that came with the car, just over five years old and Jim knew it was on it's way out. Every time he had the oil changed over the last year, the dealership would test the battery and the test showed the battery needed to be replaced. Even though it was fully-charged, it didn't have the 750 cold cranking amps for which the battery was rated. It still had enough to turn over the engine, but it was definitely on it's way out. The question was how long it would last?
Jim could hear the engine turning over more slowly and periodically connected the battery to his OPTIMA Digital 400 battery charger and maintainer, to make sure it stayed topped off, especially during the cold Wisconsin winter, when it gets really difficult for cars to start cold engines. That definitely helped extend the lifespan of the battery and we'd recommend periodically topping off the battery on any vehicle, even in a daily-driven car. The Flex has an electric-powered rear hatch, lots of interior lighting and is really laden with lots of modern electronics, including a video screen on the dashboard. That all consumes far more energy, especially when the engine is off, than cars of even 20 years ago.
When the Flex wouldn't turn over at the park on a 60-degree day, Jim knew it was time to replace the battery. He drove out with a set of jumper cables and got the Flex started, but cautioned his wife not to shut off the car, as the battery probably wouldn't have enough energy to re-start the car. He followed her to her doctor's appointment and changed cars with her, taking the Flex directly to the dealership. The total drive time was about 15 minutes, but something important was happening- the alternator was providing electricity to the car and trying to recharge a battery that needed to be replaced, which stresses the alternator and can significantly shorten the alternator's lifespan.
Why did we highlight that? Because that activity falls outside of an alternator's normal job. Alternators are designed to provide electricity to vehicles once the engine starts and maintain healthy batteries that are near a full state of charge. A battery that needs a jump-start, whether it needs to be replaced or not, is nowhere near a full state of charge. Anyone who expects an alternator to fully recharge a deeply-discharged battery by simply driving around for 10-15 minutes is moving rapidly in the direction of having to replace their alternator. Replacing an alternator is a far more costly and time-consuming endeavor than replacing a battery and that's why we always tell folks to treat jumper cables and jump packs as the electrical equivalent of a one gallon can of gas. They can get you out of a tight spot (like Jim's wife who was stuck at the park), but a discharged battery should be fully-recharged with a battery charger as soon as possible to minimize damage to a vehicle's charging system.
In the case of Jim's battery, he knew it needed to be replaced, so there was no point in trying to recharge it with a battery charger. The best course of action was to get the battery replaced as soon as possible. Postponing battery replacement any longer would likely only lead to another scenario where Jim or his wife were left stranded and unable to start the car and in need of another jump-start. Until the battery was replaced, the alternator on the Flex was getting cooked as it tried to recharge their five-year old battery and moving closer to an even more expensive alternator replacement. In fact, the alternator likely saw added stress over the last year, as it struggled to maintain voltage in a battery moving closer to being replaced.
So do all batteries that need to be jump-started also need immediate replacement? Not necessarily, but it's a good idea to have your battery periodically load-tested by a battery professional, to determine if you battery is getting close to needing replacement. It's also a good idea to keep a quality battery charger in your garage, in case your car's battery does get deeply-discharged.