If you live in a freezing place, you probably know the answer to this question. If you are not used to freezing cold weather, you may be wondering whether your car battery can freeze under extreme cold weather conditions.
Car batteries can freeze under extreme cold weather conditions. The freezing temperature of car batteries varies in the range of 32° F to -70° F depending on the battery’s age, health, and charge level. A fully charged car battery is less likely to freeze as it has a lower freezing point.
But, how exactly does the charge level affect the chances of your car battery freezing? And, what should you do to prevent your car battery from freezing? We shall cover all these topics and more in this article!
So, let’s get started!
The freezing temperature of a battery depends on its charge level. Discharged batteries are considerably more prone to freeze than charged batteries and fully charged batteries are almost impossible to get frozen because they have very low freezing points.
Fully discharged batteries (with a charge level of 11.7 volts or less) start freezing at about 0° C or 32° F. Discharged batteries (with a charge level of 12 volts) start freezing around -15° C or 5° F, and new, fully-charged batteries won’t freeze until at least about -56° C or -70° F.
This means that a new and fully charged battery won’t freeze unless you live in Siberia, Greenland, some towns in Alaska, Antarctica, or a place where the temperature can reach below -56° Celsius or -70° Fahrenheit.
These figures show that keeping a battery healthy and fully charging dramatically reduces the chances of suffering from frozen car battery problems.
Why Does a Car Battery Freeze in Winter?
The primary reason for a car battery to freeze in winter is the lower voltage of the battery. A discharged battery has more water in its cells than a fully charged battery, making it prone to freeze. Charging the battery lowers the freezing point and the chances of freezing the battery.
Standard car batteries, also called lead-acid batteries, work with electrolytes (usually a mix of sulfuric acid and distilled water) and lead plates. 12-volt batteries have six cells that are interconnected in such a way that if a cell gets damaged, the battery’s output voltage will drop under 12V.
The water-acid mixture has a water proportion of about 75 percent distilled water and 25 percent sulfuric acid. A discharged battery (below 11.7 volts) has more water in its cells than a fully charged battery, making it prone to freeze.
Do you remember your high school chemistry lessons about saturated water solutions?
Imagine a battery cell like a salt-saturated solution. The freezing point of these solutions gets lower as you add more salt to the mixture.
Battery cells follow the same principle; the water-sulfuric acid mix has a higher freezing solution than just water. Now imagine that the charge level is like adding salt to this solution. The higher the charge, the lower the battery’s freezing point will be.
What’s worse is if you have forgotten to turn off the lights of your car! This will drain your car battery faster and possibly freeze it even before you realize it! But, how long can a car battery last if you miss out on turning off the lights? Make sure you check out my other article if a car battery can die from leaving the lights on to know all the details!
A fully charged car battery will freeze below -56° Celcius or -70° Fahrenheit, which means that unless you live in an extremely cold place a fully charged car battery will be safe from freezing.
Fully charged car batteries freeze at lower temperatures than discharged batteries because as we saw above, the solution inside lead-acid battery cells has higher freezing points when batteries are fully charged.
How to Tell if Your Car Battery is Frozen?
There are multiple tell-tale signs that can indicate that your car battery is frozen. Here are some of the things that you can do to know if your car battery has frozen!
- If your car battery suddenly stops working and there has been inclement weather lately, chances are your car battery is frozen.
- Check for cracks and/or damage on the battery case.
- Check for bulges or symptoms showing that the electrolyte (mix of water and sulfuric acid) is frozen and expanded.
- Gently shake your battery and listen for any watery/liquid sound to find out if the water/acid mixture is frozen. If you can’t hear any sound, it’s probable that your car battery is frozen.
- If you have a serviceable battery you can remove the filler caps and visually inspect the state of the liquid inside every cell.
- If you don’t have a serviceable battery you can try removing the big decal that is on top of the battery. Many maintenance free batteries have call caps hidden by that big decal. Before giving up, try removing the decal and check for those cell caps. If you find them, carefully try to remove them and visually inspect each cell for frozen liquid.
If you still can’t tell, it is best to call a mechanic to check out the car battery.
Is a Car Battery Still Good If It Freezes? Can It Be Used Again?
A frozen car battery can be used as long as it has been properly defrosted and it doesn’t carry any signs of damage. Do not charge or jumpstart a frozen battery directly. Check the battery thoroughly to make sure it is safe to use again. If unsure, have it checked by an expert before using it again.
There are various issues that can arise if a car battery has frozen. As the water inside the cells expands, it pushes the lead plates, which can cause a short circuit between them.
Besides, as the water expands it can damage the battery case and other components. This can lead to leaks and other undesired effects that can ruin your battery.
If you are certain that your battery froze, you will have to check whether it’s safe to use it again. Never attempt to charge or jumpstart a frozen battery: it’s extremely dangerous.
Before trying to use a battery that was frozen you will need to call an expert mechanic, or you will have to follow a thorough checklist that includes defrosting the battery to make sure that it’s safe to charge it.
Once you have defrosted your battery and verified that the case doesn’t have any cracks, bulges, or any other signs of damage, you will have to charge it and test it to make sure that it can be used again.
Never attempt to charge a frozen car battery. It’s completely unsafe and it can have severe consequences for your health, your battery charger, and eventually, your car if you try to jumpstart it. Always follow the steps described above before attempting to bring a frozen battery back to life.
Go through the details mentioned in the next section to understand what to do if your car battery is frozen.
What to Do When Your Car Battery is Frozen? How to Revive It?
There are a few things you can do to revive your frozen car battery. For starters, you have to be sure that your car battery is frozen.
In cold weather, the first symptom of a frozen battery is a dead battery. If your starting motor turns a little when you turn the ignition on, and if your battery has enough power to let you turn on some lights, no matter how dim they are, there is a good chance that your battery is just discharged but not frozen.
However, there is a chance that your battery is half-frozen or that a cell is frozen, so it’s best to look further and not try to charge it until you are completely sure that your battery is unfrozen.
Below you will find a step-by-step guide to check and revive your frozen car battery.
- Check Battery Liquid and Warm the Battery – Make sure that the liquid inside the battery isn’t frozen. If it is, you will need to warm up the battery. Take it to a warm place and leave it for a few hours or if your car has a block heater or you have a battery blanket or thermal wrap like this one on Amazon, turn it on and wait for a few hours. Re-check your battery to make sure that the liquid inside it it’s not frozen.
- Inspect for Physical Damage to the Battery – Once the battery has been warmed up, check for cracks and/or bulges on the battery’s case and look for leaks that could indicate that the battery has been phisically damaged. If you suspect that your battery has been phyisically damaged, it’s best to discard it than to risk charging it.
- Use a Voltmeter to Check for Short-Circuit in the Battery – If the battery looks healthy, and when you are sure that it’s not frozen, use a voltmeter to check the battery’s output voltage and test that its positive and negative terminals are not short-circuited.
- Slow Charge Your Battery – After following all these steps, give the battery a slow charge. Once the charge is complete you will find out if the battery is damaged (it either won’t get fully charged or won’t hold a charge), or if it has survived and is in good shape.
After you followed these steps and you have tested the battery you will know if your battery can be used again. If you have a smart charger you will know that the battery is ok without having to plug it back into your vehicle.
There are a few things you can do to prevent a car battery from freezing in winter. These are as follows:
- Keep Your Battery Fully Charged – We already saw that it’s almost impossible for a fully charged battery to freeze unless you live in a really very cold place like Siberia.
One of the best ways to prevent your car battery from freezing in winter is to make sure that your battery is always fully charged. In order to do that, try not to leave any accessory, light, or any electronic component on overnight.
- Use Your Car Frequently – Try to use your car every day (if possible), giving the alternator the chance to fully charge your battery. Modern vehicles have many electronic systems that are left on stand by consuming energy from your battery even when you are not using your vehicle.
- Start Your Car and Idle – If you are not driving your vehicle every day, turn the engine on for 10 or 15 minutes once a day without turning on any lights, the radio or other power consuming devices, to make sure that your battery is fully charged at all times.
- Maintain Garage Temperature – If you are storing your car in a garage, make sure that the temperature inside is above 0° Celcius or 32° Fahrenheit.
- Use a Thermal Battery Blanket – If you don’t have a warm garage at home, but you have access to a power outlet, you can cover your battery with a thermal battery blanket or a thermal wrap. This will keep your battery warm and prevent it from freezing.
- Use Block Heaters for Exteremly Cold Conditions – If you live in an extremely cold area, a block heater can be a good solution to prevent your car battery from freezing. Block heaters are also plugged to the electric power grid and keep your engine oil and coolant warm.
Depending on the car battery’s location, this increased temperature will keep your battery warmer, and will make it less prone to freeze. In cold climates engines are harder to start because oil gets thicker at low temperatures; a block heater will keep the oil warmer, helping the engine to start faster and reducing the load of the starter motor and the battery. This helps to extend the battery’s life.
- Remove the Car Battery and Store Safely – If you don’t use your car daily and you don’t want to or you can’t turn on your engine every day and you don’t have a warm garage, a good way of preventing your battery from freezing is to remove it from your car and store it in a warm place.
- Use a Trickle Charger – If you have a closed space to store your car but it’s not warm enough, a good idea is to plug it to a trickle charger or battery tender [on Amazon]. These chargers keep batteries fully charged without damaging them, which will prevent your car battery from freezing.
Can a Frozen Car Battery Explode?
Generally speaking, a frozen car battery won’t explode by itself but it can explode when you try to charge it, jump start it, or boost it. Frozen batteries may have free hydrogen gases trapped inside the cell’s ice. If exposed to a spark, these gases can explode.
When you are charging the car battery, hydrogen is formed inside lead-acid batteries. Under normal operating conditions this hydrogen isn’t dangerous, but frozen batteries may have free hydrogen gases trapped inside the cell’s ice.
If these gases are exposed to a spark, there is a huge chance that they will explode, scattering sulfuric acid in the process.
Thus, never attempt to revive or charge your battery directly if you suspect that it’s frozen; it’s extremely dangerous.