How Long Can A Car Battery Last Without The Engine On (And Why)?

Exact Answer: 2 Weeks

When one buys something, let it be cheap or expensive, it must be taken care of well, for it to last long. There are many expensive things that a person can buy with money, in which some are incrementing investments while some can just deduct money from a person’s bank account. Although, it’s in the hands of the buyer whether the product bought becomes an incrementing or decrementing investment. One thing that can still be worth something close to the price it was bought is vehicles, especially cars.

There are more than a hundred models of cars in the world and though they are all referred to as cars and have four wheels, every model will have only a few similar characteristics and features with the others. Many things in a car must be refurbished and taken care of very well, and one of them is the battery.

How Long Can A Car Battery Last Without The Engine On

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

Car batteries and their lifeTime
A car battery will die when the engine is off for2 weeks
To prevent the battery from dying when the engine is off, once a week restart the engine for5 to 10 minutes
A detached car battery tends to last for6 months

Though there are many confusions and conclusions, it has finally come down to the fact that car batteries will stay in good condition even when the car is not started or driven regularly, for at least 2 weeks. During the duration someone starts up and drives the car, the car battery will start recharging itself, according to AA.

When a person doesn’t drive their car regularly, it should at least be started once a week to recharge the battery, so it doesn’t die. When a car gets a flat battery, it must be kickstarted with some sort of power surge.

When the car battery is newly installed and is full of charge, it can last for the same 2 weeks without charging it and the battery will get fully discharged after around two to three months. After 2 months, the driver will not be able to start the car at all without charging it. How long a car battery lasts depends on the device’s functioning while the car is not moving at all.

Why Does A Car Battery Last That Long Without The Engine On?

Whatever the model might be, either old or new, all the cars must be started up once a week to keep the batteries from dying. The cars should not only be started but they should also be left running for at least 15 minutes. When the car is let to run, the alternator will recharge the battery when the engine is left on.

It is also important to switch off the lights and also the AC because this can reduce the battery levels and also the diesel, which is called as “deep discharge”. When cars with lead-acid batteries go through this phase, they will not be able to get back from it.

When this keeps happening, it will certainly reduce the lifespan of the battery after the third time this happens. When a car battery is disconnected, the time it takes to discharge depends on the surrounding temperature. When the temperature is low, the battery will stay charged for a longer time, and when the temperature is high or at room temperature, it will get discharged faster.


The battery of a car becomes flat after the car remains idle for a long time, or when somebody drives it over a time limit continuously. At times like this, it is necessary to jumpstart the battery using certain methods, and it is also called the “boost” given to the battery for it to run. Without the battery, the car will never run, even if the engine is in perfect condition.

It is not recommended to jumpstart the car every time the battery dies down, but it can be done only when a car is in the middle of the road or in a situation where it must be moved immediately. Otherwise, there is an alternative for a long-term battery maintained, where a designated battery charger or a maintainer can be used. This will also help the car owners check the wattage while charging the battery.


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Hi! I'm Nidhi.

Here at the EHL, it's all about delicious, easy recipes for casual entertaining. So come and join me at the beach, relax and enjoy the food.

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