In winter, starting the engine turns into a daily test of nerves for many car owners. Even a relatively new battery can suddenly "give up", and the starter begins to turn sluggishly and uncertainly. In most cases, the problem lies not in a defect or the age of the battery, but in the operating conditions. In summer, short trips hardly harm the battery, but with the onset of frost, the usual mode begins to work against the owner.
In the cold season, starting the engine takes significantly more energy. Thickened engine oil creates increased resistance, and the battery is forced to give away a large part of its capacity in just a few seconds of the starter's operation. At the same time, it is no longer possible to restore this charge just as quickly, and the battery remains in the red every day, gradually losing its characteristics.
The reason lies in chemistry. Inside the battery is an electrolyte, which becomes more viscous at negative temperatures and conducts current worse. Chemical reactions slow down, and a cold battery is simply not able to effectively receive charge from the generator. Until the battery warms up, it is in a state of peculiar "hibernation", even if the engine is already running.
Many believe that it is enough to let the car idle to compensate for the morning start. In practice, in frost of about −20 degrees, it takes about 20 minutes. This is how much time it takes for the battery to warm up and return at least the energy that was spent on cranking the starter. All this time, the generator mainly powers the on-board electronics, and not the battery.
The situation is complicated if the battery is located not under the hood, but, for example, in the trunk. In such conditions, warming up is noticeably slower, and the time required to reach the normal charging mode can be extended to 40–50 minutes. Therefore, a short trip or a ten-minute warm-up in the yard in severe frost is not only useless, but also harmful.
A full battery charge is a completely different story. If the battery regularly experiences undercharging due to short trips, long driving is required to restore capacity. At a temperature of about −20 degrees, this takes about two hours of continuous driving. The best option is a highway or driving without long stops, when the generator is running at high speeds and the underhood space warms up well.
In less severe weather, for example at −10 degrees, this time can be reduced to one and a half hours. In severe frosts below −25 degrees, on the contrary, it will take two and a half hours or even more. Such trips do not have to be made often, but at least once every one to two weeks they allow you to remove the accumulated charge deficit and significantly extend the battery life.
If long trips are not possible, there remains a more practical alternative — charging from a stationary device. Regularly replenishing the charge in a warm room or with a charger under the hood completely solves the problem of chronic undercharging. Additionally, it is worth using energy-intensive consumers wisely and monitoring the condition of the terminals and generator. In winter, the battery is especially sensitive to operating conditions, and it is attention to detail that determines whether the car will start on the coldest day.