Why Car Battery Dies If Not Driven For 3 Days- Must Know Reasons with Fixes

It’s a common problem for many car owners that their car battery dies if not driven for 3 days. For one time, it’s okay. Car batteries lose their capacity to hold a charge over time. But if the problem is repetitive, then there are issues that you need to diagnose.

Here we will disclose the reasons behind the power drain in your battery within a short time, how you can fix it, and further prevent it from happening. Let’s jump in!

How Does A Car Battery Die?

Interestingly, the car uses its battery even if it is not active, meaning when you are not driving. Why? Because the car still needs power for the dash, ECM, alarm clock, radio, and other internal systems.

Because the whole thing happens behind the camera, and you can’t tell where all the energy is going, ultimately, the car battery dies of a parasitic drain. This happens when the car is running and also when it’s turned off.

RepairPal described the parasitic drain like this:

“Parasitic draw or drain is a term for an electrical component consuming electricity when it should not, even after it and the vehicle has been shut off. This will cause the vehicle’s electrical system to function improperly, and the vehicle may exhibit one or more of the following symptoms:

  • A persistently dead battery.
  • The engine may not crank over, or it cranks very slowly after sitting overnight.”

They also recommended performing a parasitic draw test whenever a similar incident occurs.

The situation does not improve, and often it gets even worse. So, whenever you charge, you see a faster drain than the previous time. The more you charge, the faster the battery drains. If things go unnoticed for too long, the parasitic drain leaves the battery dead to a state that you can’t even turn on the engine.

6 Reasons Why Car Battery Dies If Not Driven For 3 Days?

There can be several reasons behind your car battery constantly dying, among which the given six are the most common-

  1. Faulty Battery: A faulty, old battery can not hold too much power or provide the power that your car requires. It also does not hold the charge for long. So, the battery can run out pretty fast with a small memory function that drains in the radio, even when you don’t drive.
  2. Weak Connection: A rusted battery head connects the battery poorly. Not just the terminals but the cables and connectors can also be damaged, causing a connection issue. If the connection is poor due to a loose or weak connection, it cannot receive a charge from the alternator when you are driving. So, the battery ultimately dies after sitting for a couple of days.
  3. Light Is On: Forgetfully, you kept the headlight or dome light of your car on, which is draining power. If the light is on for night long, it can drain the battery completely. Your car may have specified headlights that remain on for a while after closing. That’s ok. But if it’s a functional problem, then the battery will drain out soon.
  4. Extreme Temperatures: Often, severe temperatures can have a damaging effect on your battery. Extremely hot or cold weather can make an old battery dead. The excess heat dries up the battery chemicals, which is crucial for operation. And freezing temperatures can freeze the battery, which becomes difficult to start later. Though it may not be as severe for a good battery, a weak one may not survive the consequences.
  5. Parasitic Drain: A parasitic draw can make the charged battery empty after sitting for a while. When it happens, the internal electrical system of your car, like the glove box, trunk lights, wired radio, etc. sucks up the battery power leaving your battery dead. This can happen without the car running. It’s like a parasite in the human body that is difficult to find. So, most of the time, you don’t understand what’s wrong with your car battery or where all the power is going.
  6. Systematic Problems: Any systematic problem, like a faulty alternator, can prevent the battery from receiving a charge. If you can start the car without any problem and the battery dies in the way, it can happen due to a faulty alternator, worn tensioners, or loose connections, which causes a fault in the charging system.

How To Keep Your Battery From Dying?

Turn Off The Onboard Electronics

Make sure to turn off all the electric systems, including the interior lights and headlights, when turning off the engine.

Upkeep The Battery Properly

If the battery is old or in poor condition, replace or repair it. Since a damaged battery can barely hold a charge, even a small drainage can empty out the battery pretty fast.

Fix The Poor Connection

​A corroded battery connection blocks the power flow. It also initiates other functional problems. Get rid of the corroded heads either by dusting off the rust or replacing them with a new pair.

Keep The Car Battery Charged When Not In Use

If you are planning not to use your car for a while, then you can do two things to retain the battery charge.

  • Loosen the connection or remove the battery altogether: When you are supposed to keep your car in the garage for a while, say for winter time or if  you are going out on a vacation, it is best to disconnect the negative terminal from the battery, or you can remove the battery from the engine bay altogether, whichever suits you better. This way, the system won’t be able to drain the battery.

If you remove the battery, make sure to keep it in a safe and dry place to maintain its durability. Also, maintain the temperature of the storage room between 40°F to 60°F, and it should not drop below 32°F/0°C, which may hamper the battery capacity and even kill it. You can use a battery box or blanket to maintain the cranking power and keep it safe from the elements. But before using the battery again, you need to charge it.

Warning!! On some car models, you may have an issue removing the negative terminal. In that case, read the owner’s manual thoroughly and learn if there is any warning regarding that factor.

  • Use a battery maintainer: If you prefer not to remove the battery from the engine bay and also keep it charged while not driving, you can go for a battery maintainer. Make sure to pick the one that is the same as your car’s battery voltage. If you want to keep your car in the garage for months long, a battery maintainer is worth every penny. Also, then you won’t have a dead battery so often or buy a new one!

Cnet says, “By contrast, car battery maintainers are all “smart” — they have sensors that allow them to “know” when they’re connected to the battery terminal of low batteries and full ones. Once a battery is completely charged they stop delivering a charge.”  

A battery maintainer makes your job easy and tension-free to keep your car battery in an optimally charged state or at least not dead. A positive side of the maintainer is that it automatically turns off when the battery is full and turns on when the battery drops at a certain level.

Remove Corrosion

Removing the rusty metal from battery terminals, connections, and cables can make the connection error-free. Apart from these, the fuse box, frame, and starter also have to be corrosion-free.

If the connection is corroded, the battery cannot receive a charge. Ultimately, it dies of a poor connection. Take necessary preventive measures when handling the battery. Also, make sure the connections are not loose after you brush off the rust.

Prevent Parasitic Drain

Fix the issues that are causing a parasitic drain in your battery. Your car’s electric system uses only a small amount of battery power when the car is off. Still, there are possibilities that it can draw a humongous amount of battery power from the system and keep the battery dead because of a parasitic draw.

You see YourMechanic warns this as follows,

“If the relay shorts, it can leave power on to the computer, even when the vehicle is turned off. This will place a parasitic drain on the battery, which will eventually cause it to go dead.”

Optimal Operating And Storage Temperature

The operating temperature affects battery performance greatly. The upper temperature should not go above 35°C or 95°F whereas the lower temperature should not go below 4°C or 40°F for optimal battery performance.

Fix Systematic Issues

Check whether the alternator, alternator belts, tensioners, connectors, and other systematic things are working optimally to keep the charging flow constant. If the circuit works, it will make a ‘click’ sound when you turn the key. Also, the wires and alternator belts should be flexible and crack-free. Tighten any loose connections and replace any worn-out parts to make the system work again.

How Long Can a Car Sit Before the Battery Dies?

Without knowing the ideal sitting time, if you stop driving your car for a long time, it can cause your car battery to have a devastating ending. So, it is crucial to know how long your car can sit before the battery dies.

The battery longevity in this situation entirely depends on a few things, like- the car type, battery age, and also operating temperature. Typically, a charged car battery can last for about four weeks to two months without the car being driven. However, with a parasitic drain problem, a car battery can barely survive that long.

Frequently Asked Questions (FAQs)

Why does my car battery die after sitting for a few days?

An old battery can die after a few days of sitting. Battery cells get damaged for constant use. So, the old batteries cannot hold a charge for long periods. So, they die after a few days of sitting. For new car batteries, it’s not usual. It may happen due to a power drain. Check for a faulty relay, lit lights, plugged charger, or wired radio. Also, run a parasitic draw test.

Is it normal for a car battery to die after sitting for a week?

Normally a new or good car battery won’t die after a week of sitting. There can be several reasons behind this, and you need to diagnose that first. This is most common for old batteries. They cannot hold a charge for an extended period after a certain time frame. If this happens regularly, your car battery definitely has a problem, and it may need a replacement. If it is a wet cell battery, you may need to replace it every three to five years.

What drains my car battery when it’s off?

Your car battery may have been sucked up by a parasitic drain. The internal electric system of the car can draw battery power even when the car is turned off. It can also happen if you mistakenly keep a light on. Another common reason can be a faulty relay which keeps the power on to the electric system, eventually ending up with a dead battery.

Does a battery fail when you don’t turn your car on for 5 days?

Modern car batteries can last up to two months, even without a start. So, if your battery is intact and in good condition, it should be fine. But a parasitic drain issue can kill the battery even before five days have passed. To keep the battery healthy and durable for a long period, starting the engine only once a week should be enough.


When the car battery dies if not driven for 3 days, it’s crucial to find the reasons and take steps accordingly. Whether it’s a parasitic draw or a poor connection, diagnose the battery condition and take measurable steps promptly. Also, it is not ideal for parking the car in extreme temperature conditions, which damages the battery even more.

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