Battery draining over night when cold outside

How do I find out what's draining my battery overnight only in the cold weather! Nothing is being kept on?

My car has 114200 miles.
My car has an automatic transmission.

Experienced mechanics share their insights in answering this question :
Hi there. The most common cause of a battery draining when it is cold outside is simply a failing battery. When a battery is old and becomes weak it will drain in cold weather. I usually start by load testing the battery. If it fails then it needs to be replaced. If not then most of the time this is caused by an ignition switch that is shorting when it is cold or a failing body control module. If there are not any other electrical concerns then it is usually the module that is failing. If you need to have this battery issue looked at, consider YourMechanic, as a certified mechanic can come to you to [diagnose why the battery is draining] https://www.yourmechanic.com/services/service-battery-cables

How to Identify and Fix Common car Problems ?

Our sources include academic articles, blog posts, and personal essays from experienced mechanics :

Why does the cold drain battery power? Most batteries work through an electrochemical reaction, which sends power signals to your terminal ends. This chemical reaction slows down in colder weather, weakening your battery`s power.
Lights left on.

That can be your car headlights, dome light, light in the glove box, or trunk light. Even vanity mirror lights can drain a battery if left on overnight.

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.”
Having a good quality battery blanket wrapped around your battery will keep it insulated and warm at night when plugged in. Keeping your battery fully charged will also help. A weak battery can start to freeze at 0C, while a fully charged battery won`t freeze until about -60 C.
Cold temperatures can cause condensation to form inside the battery, which can lead to corrosion. It dilutes the electrolyte and, in rare instances, it can cause the battery to short circuit too. Make sure your battery is properly charged. A fully charged battery is less likely to freeze than one that is low on power.
What Type of Battery is Best for Cold Weather? An Absorbed Glass Mat (AGM) battery is better for cold weather versus a standard flooded battery (or what we might classify as a “normal” car battery).
LiFePO4 or LFP batteries are suitable for almost all conditions(temperatures ranging from -4°F to 140°F(-20C to 60C)). Lithium batteries are an excellent alternative for continuous, dependable power for off-grid solar, RV, and Camper Van owners who live or travel in extremely cold climates.
There are too many apps running in the background. The screen is too bright. The screen is staying on too long before going to sleep. The phone doesn`t have service.
Contrary to its purpose, an alternator can drain a battery. It`s rare, but it`s possible. A draw on the battery only occurs if there`s a problem with either a component in the alternator itself or connections to it.
Cold weather slows everything down, especially the chemical reaction happening inside your car battery. In fact, at 32°F, a car`s battery loses about 35% of its strength. And at 0°F, it loses up to 60% of its strength—but your engine requires nearly twice as much power to start!
Does Cold Weather Permanently Damage Batteries? If your phone has shut down due to cold weather, the impact on your battery is only temporary. Permanent damage can occur, however, if you attempt to charge your phone at freezing temperatures.
Most people believe cold weather is what kills the battery, but it is hot weather that shortens the lifespan of the battery. When the battery gets cold, the chemical reactions are slowed. Slower chemical reactions can prolong the useful life of a battery by slowing the degradation of normal usage over time.
The primary factor in determining the number of CCAs necessary to start a vehicle is the size of the engine. The standard recommendation is that a vehicle battery should possess at least one CCA for every cubic inch of engine displacement (two CCAs in the case of diesel engines).
How Many Cold Cranking Amps Do I Need? A good rule of thumb is that an engine will need about one amp per cubic inch of engine displacement.
No charge permitted below freezing. Good charge/discharge performance at higher temperature but shorter life. Batteries can be discharged over a large temperature range, but the charge temperature is limited. For best results, charge between 10°C and 30°C (50°F and 86°F).
If you must use disposable batteries (non rechargeable) then lithium batteries are the only good choice. They have shorter life at low temperatures but are still much better than alkalines. In the AA battery size, lithium and NiMh batteries are the best cold weather choice.
Yes! It is absolutely normal for a phone`s battery to drain by 10% overnight. It happens due to all the background processes going on in the phone. If you really want to save battery, then you must turn on airplane mode, and block the background processes before you go to sleep.
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.
Issues such as faulty wiring, bad fuses or interior lights that fail to shut off will continue to drain your battery while it`s idle.
The ignition relay is essentially an electrical device that works as a switch for the power to the ignition system. Its job is to make sure electricity flows from the battery to the different components that need power. A bad relay will drain your battery and make it difficult to start the ignition.
Symptoms of a burnt out diode:

The engine will begin to run rough, lack power and eventually stall and not start again. The battery warning light will turn on, warning you that there is a problem with your alternator charging system. The headlights will become dim due to reduced battery voltage.

Probably, the most common symptom associated with a bad regulator is flickering, dimming, or pulsing lights. To be more specific, you may notice that the vehicle`s: Headlights fluctuate between bright and dim, without you doing anything. High beam isn`t working as expected.
Car batteries work best at a temperature of 27°C. By the time the temperature falls to 0°C, even a fully charged battery has lost around a third of its starting power. Cold weather also means that more energy is required to crank the engine, creating a double effect of less available power and increased energy demand.

Relevant Questions and Answers :

the most relevant questions and answers related to your specific issue

Battery drains quickly, New battery,Heavy drain, Replaced alternator , drain still there,goes away when bat. main 2 fuse is pulled
ANSWER : Hi there. It’s quite possible that you have one of two things causing the drain to the battery. First, you have a bad ground somewhere in the main relay or fuse box or an exposed wire somewhere that is not allowing the circuit to complete from the alternator to the battery. This can cause a battery draining issue as you’re describing, but it could also be one of multiple other electrical problems. The best way to pinpoint the exact source is to have a professional mobile mechanic come to your location and complete a battery will not hold a charge inspection.

Battery light stays on and overnight battery drain. 2006 Land Rover LR3
ANSWER : Hi there – yes, something is going on here that’s draining your battery. Perhaps the pressure of the engine wash dislodged wiring which has shorted, or there was a chemical reaction to the cleaning solution that caused electrical damage in the alternator or voltage regulator. These componnents can be checked off of the vehicle. Vehicle wiring can be diagnosed by connecting an ammeter to the positive (red) battery cable, observe the current drain (likely less than 1 amp), then, one at a time, remove each fuse, check to see if the current drain has dropped to near 0, then reinsert the fuse. This process should identify the faulty circuit in most cases. The specific components on that circuit can then be checked for current drain problems. A professional mechanic, like YourMechanic, can come to your location, and perform this procedure for you, and replace/repair the failing component.

Battery keeps getting drained while the car is off during the night
ANSWER : Hello there, thanks for writing in about your 2009 Chevrolet Aveo5. Batteries that drain overnight are not uncommon. This is called a parasitic drain and can have many different causes. The most likely are any aftermarket electrical accessories, such as the radio, a power seat, window switch, dome light or wiring fault. I recommend having a certified technician look over the vehicle’s electrical system in order to diagnose why the battery keeps draining and make the necessary repairs.

I have Chrysler 300c. Battery light came on, changed battery and alternator but power still getting drained and battery light still comes on.
ANSWER : Hi, thanks for writing in. This may be a sign of a failing starter relay. The starter relay is a small unit near the starter that directs power to the starter from the battery. When this fails, it may cause a clicking sound and will not allow the starter to engage the flywheel when you turn the key. I would suggest having a professional from YourMechanic come to your home to diagnose your starting issue to determine the solution to get you back on the road.

Battery light stays on and overnight battery drain. 2006 Land Rover LR3
ANSWER : Hello – this problem can be diagnosed by connecting an ammeter to the positive (red) battery cable, observe the current drain (likely less than 1 amp), then, one at a time, remove each fuse, check to see if the current drain has dropped to near 0, then reinsert the fuse. This process should identify the faulty circuit in most cases. The specific components on that circuit can then be checked for current drain problems. A professional mechanic, like YourMechanic, can come to your location, and perform this procedure for you, and identify, replace or repair the failing component.

Battery drains overnight – 1990 Cadillac Allante
ANSWER : This problem can be diagnosed by connecting an ammeter to the positive (red) battery cable, observe the current drain (likely less than 1 amp). Then, one at a time, remove each fuse, check to see if the current drain has dropped to near 0, then reinsert the fuse. This process should identify the faulty circuit in most cases. A professional mechanic, like YourMechanic, can perform this procedure for you, and replace/repair the failing component.

Auxiliary battery draining the hybrid battery
ANSWER : Auxiliary batteries can take awhile before symptoms may be noticed on a Prius. This is due to the hybrid system powering many of the components. In this vehicle the auxiliary battery is mainly used for starting. It could cause problems if not installed properly.

I’d recommend getting some help from qualified technician who will be able to diagnose the source of your battery issue and assist you with any repairs that may be necessary.

Can disconnecting your car horn cause your car battery to drain over night?
ANSWER : A horn being disconnected will not cause the battery to get drained. The battery being drained or low on charge after sitting should first charge and test the battery then check to see if the vehicle has a draw on the battery. There is a possibility that the alternator is drawing the battery down and should be tested by a mechanic like one from YourMechanic.