Why do car batteries discharge and how to prevent it?
According to data from the German Automobile Club (ADAC), as many as 32% of all vehicle breakdowns are caused by battery issues. However, in most cases, the battery itself is not at fault — the problem lies in choosing an inappropriate capacity that doesn’t meet the energy demands of modern vehicles. Battery manufacturer “Banner” identifies seven main reasons why batteries discharge prematurely and provides practical advice for drivers.
1.Increasing number of electrical devices in cars
Modern cars are equipped with numerous electronic systems — from comfort features to safety equipment. More than 100 devices can demand up to 5000 W of power, which exceeds the generator’s capacity. As a result, the battery often becomes the primary energy source, causing it to discharge faster.
Tip: choose a battery with as high a capacity (Ah) as possible to handle the increased load.
2.Factory-installed batteries that are too weak
To reduce manufacturing costs, some car manufacturers install batteries with insufficient capacity. Such batteries are unable to reliably power all systems, especially when they are controlled by computerized modules.
Tip: when replacing the battery, choose one with the same or higher capacity than the original.
3.Additional devices not intended by the manufacturer
Navigation systems, auxiliary heaters, or entertainment devices all require extra power. If the battery is not designed for this, its lifespan will shorten. It is particularly recommended to use AGM-type batteries, which are more resistant to frequent charging and discharging cycles.
Tip: consider your driving habits and use of additional equipment — it may be worth investing in a more advanced battery technology.
4.Capacity is more important than cold cranking amps
In modern vehicles, the most important battery parameter is capacity, not cold cranking current. Over the past decade, energy demands have doubled, making capacity the key factor for longevity.
Tip: when choosing a battery, prioritize capacity (Ah) rather than just starting current (A).
5.Frequent battery use without full charging
A battery that is often used without being fully charged wears out faster. For example, if it’s discharged by 50%, its lifespan can be up to five times shorter than one discharged only by 20%.
Tip: recharge your battery at least twice a year to extend its service life.
6.Short and infrequent trips
If the vehicle is used rarely or only for short distances, the battery does not have time to fully recharge. Over time, this leads to reduced performance.
Tip: use a charger with a maintenance charging function if your car remains unused for extended periods.
7.Low temperatures – a serious challenge
Cold weather reduces battery efficiency, while the engine requires more power to start. Even a few degrees below zero can increase starting power demand by 50% and reduce battery capacity by up to 80%.
Tip: do not crank the engine for more than 5–10 seconds. If it fails to start, wait one minute and try again. Turn on additional devices only after the engine has started. Always use the highest-capacity battery possible.
