Why Would Cold Temperatures Kill a Battery?

Anyone who’s come out on a bitter winter morning to find their car battery won’t turn over knows that the cold and batteries don’t mix particularly well. When a battery is connected and the engine is on, there is a chemical reaction that produces electrons. These supply the battery’s current and at normal temperatures they’ll produce enough current to keep the battery power full and working well. The more you drive, the more the battery charges.

However, when the temperature falls it becomes harder for the battery to produce enough current to stay at maximum potential. That means the reserves drop. This is why, when it’s chilly, it can be harder to start your car. There has to be enough juice in the battery for it to turn over the engine so that it can then produce more energy. This is especially true when the car is running a radio, lights, and heating, which are all additional drains on the battery. In very cold weather the power that’s available, even from a battery that’s fully charged, is only half what it would be in warm weather.

Why Does a Battery Die?

If the car battery is old, it’s not going to be able to produce as much current as it did when new since all batteries eventually wear out, even rechargeable ones. An older, cold battery will likely be unable to deliver enough current to start your car. You might hear the familiar chugging noise as it tries, followed by silence as the battery loses the last of its charge.

Natural leakage between the battery terminals also reduces the current. However, this only happens slowly and should not be an additional factor in cold weather unless the battery is already old and weak. But it’s not just car batteries that are affected. Cold affects all batteries so anything that runs on them probably won’t work as well if exposed to the cold for long periods of time.

Warming a Car

If the engine is warm before you try and start it, it will be far more likely to start, even with a weak battery. Some cars, especially those sold in cold weather areas, are sold with plug-in engine warmers that can be used overnight. The heat also reaches the battery so it’s not as cold as it would be if left to stand normally and the chemical reaction is there as soon as your turn the key. A warm battery will have enough current to start the car. You can also buy a battery heater, which means your battery will lose a lot less power in the cold.

If possible, you should park your car in a garage or car port where it can be protected from some of the elements. Some people also remove their battery on especially cold nights and keep it in the house where it’s warm. This also makes morning starts a lot easier, but you will need to be careful about where you place your battery when it’s been taken out. Do not put it directly on any surfaces, such as concrete flooring, that hold colder temperatures. Set it on a slab of wood on top of the concrete if you decide to store your battery in such an area to prevent a temperature sink from draining the battery completely. If left in the house, your battery should be kept off of counters and tables in living spaces.

Once you’ve started your car, you need to drive it for at least half an hour for the battery to charge fully.