Why does a battery perform less in the cold?

This is about the basics of battery behavior in the cold. You know that when it gets colder, the performance of batteries changes. That is already the case with an old-fashioned lead-acid battery to start. This causes more problems in the winter than in the summer. And with electric cars it is known that when it is cold the range becomes a lot smaller.

Multiple causes in electric cars

There are several reasons why an electric car has less range. It is of course important that the heating must be on and that costs energy. Especially if a car has not charged from the plug overnight, a lot of energy is needed for a while to warm up the car. Make no mistake, it’s almost as much energy or power as it takes to power that car. If things go wrong, there is therefore a chance that the range will be halved.

Processes in the battery

Things also happen in that battery when it’s cold. Picture the battery as a container with liquid and separation. There is an electrode in it, the negative pole, and on the other side you see the positive pole. A connection for electricity consumers will be placed between the two electrodes. That can be a light, but also a motor.

The negative electrode is made up of carbon, while the positive pole often consists of cobalt oxide. It could be something else, but that’s often the case with a lithium-ion battery. The electrodes contain lithium. As soon as the current starts to flow, an electron is released from the carbon. This goes through the electricity grid to the positive pole. So you are left with carbon with a separate lithium molecule, which will split. That becomes a lithium with a plus charge and a negative electron. This goes through the electricity grid and the consumer to the other side, so the positive pole. Meanwhile, the lithium also passes through the liquid, gel or solid structure of the battery to the positive terminal. This is what happens in the battery when electricity is consumed. When we charge the battery, it goes the other way.

How does the battery work in the cold?

That works fine at room temperature, but that’s not always the case. If the temperature drops, the capacity can go all the way to zero at -30 degrees. At that temperature everything goes slower and the ions then split more difficult from the carbon and release more difficult electrons. As a result, the current decreases and with it the power. At the same time you see that the internal resistance of the battery cells increases. The liquid or gel becomes more viscous, so to speak. At a certain moment the resistance is such that the electrons no longer want to get out. As a result, the battery can hardly supply energy at about -40 degrees.

So you have to keep the battery warm. That’s easier said than done. When you have it on the charger, the battery is normally cooled by a cooling circuit. You can also use that to warm up the battery in the cold, so that charging goes better.

It is not the case that the battery is empty if you have it in the cold and nothing comes out at -40 degrees. It’s not like you’ve lost all the energy you’ve pumped into it. When it gets up to temperature, it also comes back to life, because the lithium is still in place and it then calmly moves away from the carbon to the positive pole. So it slows down in the cold.