How Long Can a Car Battery Sit Unused? – You Need to Know

Today, most people prefer to leave their car batteries to sit unused for a few primary reasons and decide to use public vehicles to save their batteries from wearing out faster. How long can a car battery sit unused is normal for any car owner since you need to know the time you can spend without using the car battery, and it cannot affect the car’s functionality. The question requires an answer as soon as possible to help you take care of your car when not use.

The most common answer here is that a car battery can sit unused for a period of about one or two months without use. The answer helps an individual mind when they leave the car without using it most of the time. The battery stays unused when the car is not moving. The period the car battery can last unused depends on the temperatures that surround the car. The article below discusses how the car can stay unused and what causes the car battery to sit unused.

What determines the period a car battery can sit unusedHow Long Can A Car Battery Sit Unused

Before calculating the period, the car battery can sit unused and first determine the primary cause of the period. Below are the determinants for the period of the battery since some people leave their battery to sit unused, and they get them in their good condition as some drain faster in not more than a week.

  • The temperatures that surround the car battery at the time of parking

To keep a car battery for long without using it, consider checking the temperatures that surround the car and its batteries. For example, in this case, when you keep the car battery in a place with shallow temperatures, the battery will lose its charge at a higher rate than when the temperatures are at an optimum temperature. The reason behind this is that the battery loses its charge during the cold season due to the density of the electrolyte in the battery.

In most cases, the electrolyte in any car battery is always in a liquid form. However, when the temperatures are shallow, the density of the electrolyte becomes low as well, which later makes the electrolyte form crystals that cause damage to the electrolyte plates that cover the battery. The damages to the battery plate accumulate for some time, making the battery lose its strength towards storing energy that powers the car’s engine.

Therefore, to maintain a more extended period so that the car can sit unused for always park the car in areas with optimum temperatures. When you attend meetings or go for vacations in your car and park, you can stay longer with the batteries. If you are sure the places you are visiting have low temperatures, make sure you leave the car at a different and secure place for parking so that after the vacation, you can use it to come back home.

  • Age of the car battery

The age of the car battery determines the time the car battery will sit unused. If the car battery is new, meaning it lacks damages and the connection is still since it has faced fewer vibrations when moving, it can sit for long without draining. However, when the car battery is old enough, it can stay for a week or below since the battery is weak enough to store power for a long time.

Therefore, if you want to use your car for vacations that will take much time, consider replacing the battery before moving away from home to avoid such silly acts with the car battery.

  • The low battery of the car before leaving it unused

Car batteries tend to lose charge when parking a car with a battery percentage that is very low such that the battery drains quickly due to some minor reasons. But when the battery is complete, it will lose charge, and at least you will have some power that can start the car such that you can connect it for charging when the car is moving.

So when parking cars for vacations, make sure you connect the battery to a smart charger to keep on charging while you are away. Moreover, since you are using an intelligent charger, it will disconnect when the battery is full. After the vacation, the battery will have its charge that can start the car for your journey.

The time a car battery can sit unusedThe time a car battery can sit unused

It is easy to calculate when a car battery can sit unused so long as the temperatures are optimum and any other factors that contribute to battery loss are okay. During the average optimum temperatures, a car battery drains about ten milliampere-hours of charge per hour when idle, making it easy to calculate the time.

It is essential to determine the ampere per hour of charge the battery loses when working before finding the amount when idle. To calculate this, see the least amount of amperes per hour of working. Ampere per hour is the unit that shows the amount of charge in the car battery.

Let’s say a car’s battery at any typical environment when it is full its charge has a percentage of about 100A/h. The least amount of ampere per hour of working results from a point where there is a lower point the charge value cannot overpass. To calculate the least amount, consider dividing the maximum charge, which is 100A/h, by 3.3. For example, let’s take the total amount to be 100A/h the divide it by 3.3.

100A/h/3.3 = 30A/h

It shows when the car battery charger is about 30A/h. It is in its most negligible value such that the car will fail to start as the battery has less power to power the car’s engine.

To calculate the idle time, which helps us determine the period a car battery can sit unused, is by finding the differences between the value when the battery is full of charge and the minor charge when working. It isn’t effortless but is easy to understand. Using the figures above, let’s assume the total charge is 100A/h.

Therefore; the least amount of charge when working is 100A/h/3.3 = 30A/h, then subtract 30A/h from the full charge, which is 100A/h-30A/h = 70A/h, which is the least working charge.

Divide the least working time with the original rate at which the battery loses its charge, which is 10mA/h that when you convert to A/h results to 0.01A/h

70A/h/0.01A/h = 7000hours

7000 hour/24 hours = 291 days

Two hundred ninety-one days is now the period that your car battery can sit unused.


The above calculation is an assumption that guides you through calculating the period with your since batteries are different from different manufacturers. If you feel like knowing the exact time a car battery can sit unused is essential, you can then set the battery to notify you after many days.

Finally, the article above shows the amount of time the car battery can sit unused so long as the conditions are optimum. However, take much care when doing the calculations since when you mess with the math, the number of days will have an error that can affect your plans with the car. Therefore, consult a mathematician if you have difficulties with the calculations.

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