Can A Car Battery Freeze?

Winter weather puts a lot of stress and strain on cars, and in particular the car’s battery. Cold weather can make it harder for you to start your car because it reduces the battery’s output and also increases the amount of power required to start the car. In addition, cold weather reduces a battery’s capacity to hold charge, and also tends to increase the amount of demand we put on the battery through the need for windscreen wipers, lights, and heaters. Together, all of those things are a horrible combination.

Why do car batteries freeze?

Car batteries freeze because they contain liquid. That liquid isn’t just water – so a car battery isn’t going to just freeze when the temperature hits zero, but it is still a liquid. Most batteries won’t freeze until somewhere between -30 degrees F or minus 50 degrees F. A battery that is not fully charged could freeze at a warmer temperature, and a battery that is flooded could freeze at a warm temperature too.

How do car batteries freeze?

Car batteries contain a mixture of sulphuric acid and distilled water. If, for whatever reason, the mixture separates, the distilled water could freeze. A battery that has been damaged in very hot temperatures may be more susceptible to freezing like this.

Is a car battery still good if it freezes?

If a car battery freezes, then there is a high chance that it is irreparably damaged. It is possible that it could be salvaged, but you will need to be careful if you are going to try. When the water in the battery freezes, it expands – and that could push the plates inside the battery together, causing them to short. In addition, the expansion of the water can put pressure on the case, causing it to split.

It is possible to thaw out a frozen battery, and that might be enough to resurrect it, but you should do this carefully. In many cases, it’s wiser to simply replace the battery.

What temperature do car batteries freeze at?

The freezing temperature of a car battery depends on the chemical makeup of the battery and how much charge it has. In theory, a fully charged battery should not freeze until -76 degrees F. A battery that is completely discharged will freeze around – 30 degrees F.

It’s almost impossible to keep a car battery fully charged at all times. Cold weather actually reduces a battery’s ability to hold charge in the first place. This means that in the winter your batteries are going to be more susceptible to freezing.

Modern batteries are billed as being ‘maintenance free’ and this means that we tend to forget when they were last charged, or even cared for at all. Failure to notice warning signs such as a slow clock, dim headlights, or difficulty starting the car could lead to the battery’s charge becoming incredibly low – and therefore increasing the risk of the battery becoming frozen.

How to unfreeze a car battery?

If a car battery freezes, then it is not a good idea to keep using it, instead:

  • Perform a visual inspection of the case. If you notice that there are cracks in the case, it is very likely that the case is damaged beyond repair. Have an expert come out and take a look at it.
  • If the case appears un-damaged, remove the battery from the car and leave it in a warmer, safe spot.
  • Let the battery thaw out naturally. Do not attempt to heat the battery in any way.
  • When the battery has thawed out fully, re-install it in the vehicle. If the battery works well enough to power your lights, then take some time to re-charge the battery, because the freezing process will probably have significantly discharged it.
  • If the battery does not power the lights, have an expert inspect the battery and test it. Don’t try to recharge a battery that has been frozen, and is completely dead, yourself.

How to start a car with a frozen battery

You cannot start a car with a frozen battery, because a frozen battery no-longer works as a battery at all. When a battery is simply “flat”, you can jump-start the car, and then the engine’s power will slowly recharge the battery. Your car’s engine needs a battery in the circuit for it to keep running, and a frozen battery can’t do that job.

So, if you have a car with a frozen battery, you will need to replace that battery (at least temporarily) to get the car to run. Even a discharged battery will suffice if you just need to get the car jump-started so you can get it to the garage. You can try to thaw the frozen battery out if it is not irreparably damaged, and it may be possible to salvage the frozen battery for use at a later date. However, if a battery is in such a poor condition that it was possible for it to freeze, and you don’t live in an area where the weather is consistently exceptionally cold, you should consider replacing the battery as soon as possible.

Car batteries should be handled with care. Do not try to thaw out a battery using heaters, and do not try to use a battery that is leaking or showing visible signs of damage. If you have any doubts, call out a qualified mechanic to have a look at your car for you.

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