How Long Can a Car Battery Last Without The Engine On?

How Long Can a Car Battery Last Without The Engine On

Naturally, there are electric systems in vehicles that need a battery to run, and without car batteries, these electric components won’t kick start. This is why, even with gas and engines, cars have batteries.

An excellent battery with a proper battery capacity sends steady electric currents throughout all parts of the vehicle, powering things like the radio, Kickstarter, security systems, and other electronic components in the vehicle.

While it powers these components, it also has to be charged, and the engine of the vehicle charges the battery whenever it is on. In light of this, how long can a car battery last without the engine on?

A standard car battery can last between 10 and 14 days without the engine of the car running depending on the capacity of the battery and its condition, and the number of electronic components existing in the vehicle.

Can You Leave Your Car Engine On For a Long Time?

Your car engine runs as long as you are driving, so, under the right conditions, if there is enough fuel in the fuel tank, and there’s enough water in the radiator to avoid overheating, your car can go on for as long as 8 hours or more.

By that time, your fuel would have been exhausted, and once you add fuel to your car, it can begin to run again, and the beautiful thing is, while your car engine is running, your car battery is charged.

How Long Can a Car Battery Last Without the Engine On?

The length of time to which a car battery can last without the engine on varies with the capacity and potency of the battery, and also the electrical demands or requirements of the vehicle it is in.

However, a standard car battery should last for an average of 10 to 15 days without the engine running. This is an average measurement, as there are batteries that can last for more than 15 days before they go off, and there are some that last for lesser than 15 days.

The amount of time, again, largely depends on the situation, such as how strong the battery is, the capacity of the battery, the electrical components of the vehicle the battery is powering, and whether or not the battery is connected.

Consequences of Letting Your Battery Die Without Recharging

You have to keep your car battery charged up to enable it to power your car. If your battery is completely drained, that is, it completely dies without you recharging it, no miracle can power up your car, unless you find another car battery.

There are several consequences of letting your battery die without recharging it, and we will talk about a few in this article.

It Can Cause Total Damage to Your Battery

If your car battery dies consistently or gets completely drained of power before you recharge it, over time, the battery dwindles in potency, and eventually, it damages totally, and cannot be repaired. This damage is due to what is usually called excessive sulfation.

Your Car Won’t Start

Without the car battery, your car won’t start, no matter what you do. And if your car doesn’t start, you won’t be able to make use of it, until you get another battery. This is one of the consequences of letting your battery drain without recharging it.

Drained Batteries Will Lead to Delays and Embarrassment

Imagine you have to go somewhere early in the morning, say you need to get to a meeting, and when you get into your vehicle, you realize that your car battery is drained, and it won’t come on.

You have to go and look for another car battery just so you can kick-start your car, all the while wasting time and getting delayed from the meeting.

What To Do if Your Battery is Flat

When you find out that your car battery is flat, and you have to drive, the best way — although not so easy — is to jump-start your car.

To jump-start, you need another person to lend you his car battery, and this is where it gets tough, as if your car battery goes flat somewhere you don’t know anybody and nobody knows you, it will be difficult to find a good samaritan to come to your rescue.

You can also make use of a jumper cable to jumpstart your car. Jumper cables can be found in gas stations and other online and offline stores.

Another thing you can do if you find out your battery is flat is to add water, particularly distilled water to the battery. You might be in luck and find that there is still action that would cause a reaction once you try to start your car using the battery again.

Usually, this isn’t a method that births a lot of success, so your best chance at fixing the problem of a flat car battery is getting another car battery to jump-start your vehicle.

How Long Can a Car Battery be Dead and Still be Recharged?

A car battery must not be left dead for more than two months if the owner intends to recharge it later on. If a car battery is dead and not recharged for more than two months, it won’t power up anymore.

If you leave a car battery without starting it or making your engine run, it can still last for as long as thirty days, depending on the potency of the battery.

However, after thirty days at most, it dies, and if it remains dead for more than two months, chances are it won’t come back on any longer.

How Many Times Can A Car Battery Be Recharged?

You can recharge a car battery as many times as possible during the life of the battery. You can recharge it as much as one thousand times while the battery is still potent.

Of course, over time, depreciation will set in, and you will have to change your battery. Chances are, by the time you have to change your battery, you can’t have recharged it up to one thousand times.

How Long Can a Car Battery Last With The Ignition On?

A standard battery will last between two hours and five hours when the ignition is on. Again, this completely depends on the capacity and potency of the battery.

It also depends on the number of electronic demands on the vehicle the battery is running on.


It is advisable to always turn on your engine for about fifteen to twenty minutes to recharge your battery if you haven’t used your car for up to fifteen days. This is to ensure that the battery of your car doesn’t die. If your battery dies, it’s usually another delay, and it can also hurt your battery when it dies all the time.