7 Things That Can Drain Your Car Battery (2023)

FAQs

What drains your car battery the most? ›

“Electrical devices or lights left running, a defective charging system or alternator, and extreme weather are some common reasons but maybe it's just time to get a new battery.”

What may drain a car battery when it's off are things such as interior lights, door lights, or even bad relays. While your engine runs, the alternator recharges the battery — which is why you typically don't have to worry about the battery dying while you're blasting the radio on your drive to work!

Factors that can shorten its life include an extended period of partial or full discharge, vibration from not being properly secured, under- or overcharging, extreme temperatures, water loss, electrolyte contamination and corrosion on terminals.

Question: Does having your air conditioning on while you start a car engine shorten the battery life? Answer: In a word, no – as long as your car was made in the mid-1980s or later.

This happens when something – a glovebox light, an amplifier, any electrical component – is pulling power from the battery when it shouldn't. Since the alternator isn't generating vehicle electricity, the problem component pulls from the battery, slowly draining it overnight until your vehicle won't start.

Generally, the larger the battery is, the more capacity it has for energy storage. So even though a big and small battery are both rated at 1.5V, the big battery stores more energy and provides a longer battery life.

How do you drain a battery in 5 minutes? ›

If the engine starts but dies immediately, your alternator probably isn't keeping your battery charged. If a jump starts and keeps your car running, but the car can't start again off of its own power, a dead battery is probably your answer.

How Long Does It Take To Charge A Car Battery? If you have jump-started your car, it is recommended to let your vehicle run for at least 30 minutes because it would typically require at least half an hour to charge a dead battery entirely or at least sufficiently.

Turn off functions like the radio or air conditioner when your engine isn't running to put less wear and tear on your battery power. Extended periods of idling also can wear a battery down.

Typically, a car battery will last for about 5 to 6 years and about 30,000 to 50,000 miles before needing to be replaced. It is a relatively minor cost to keep your car running strong.

Service experts estimate that you should replace your car battery every four to five years. Real-world battery life varies depending on a couple of factors, but you can find out how to know if your MINI Cooper battery needs to be replaced in this helpful guide.

The answer is no, leaving your windshield wipers on when the car is shut down will not drain your vehicle's battery. Since the wiper blades won't be moving, there's no drain on your battery.

Will turning the AC on while parking harm my car even if I put it on a high level? No, not as long as your cooling fans are working. Cars are made to run all day long with the AC on. If they have the cooling fan working, sucking air over the radiator into the AC condenser.

Yes: The alternator, which is powered by the engine, is what provides energy to the air conditioner. The engine runs on fuel, meaning you are using up gas when you run the AC.

If your battery has been run dead too many times, has too much internal sediment buildup or is simply too old, it may be losing its ability to hold a charge. This means as soon as you turn off the engine, the battery starts discharging on its own even if the alternator works fine.

What is the most common cause of parasitic battery drain? ›

Several things could be causing problematic parasitic battery drain, including short circuits or electrical devices that remain energized, including: Under-hood or glove-compartment lighting. Headlights. Computer module.

“A key fob will constantly try to communicate with the car. And that does cause a slight drain on the battery, but generally that won't completely drain a healthy car battery,” says Mike Monticello, Consumer Reports' road test manager. “The key fob is, in a sense, causing the issue.

The 40-80 rule is a way to maximize the lifespan of your battery by limiting the damage ; specifically it refers to not discharging below 40% and not above 80%. Charging above 80% becomes increasingly cause damage to the battery life cycle. Normally the life cycle of lithium ion battery is 300 to 500 charge cycle.

If you let the charge drop too low, your battery can become irreparably damaged. So, how low are we talking? A typical 12-volt auto battery will have around 12.6 volts when fully charged. It only needs to drop down to around 10.5 volts to be considered fully discharged.

A corroded or defective alternator diode will faultily continue charging the circuit even when the car off. This, in turn, will drain your car battery and cause the car not to start.

Can AutoZone test your alternator? ›

Alternator Testing

Dim or flickering lights, dead battery, battery light on, trouble starting or other issues. How to get your alternator tested: Just to visit a nearby AutoZone. We'll test the alternator while it's still in the vehicle.