Almost most drivers have realized that aftermarket batteries don't last as well as original batteries. In the manufacturing plant and during the production of the cars, batteries are put in which have a lifespan that often exceeds five years.
On the contrary, those of the trade last less years. This is mainly because car manufacturers, during production, are bound by strict specifications and aim for quality. So they are responsible if something goes wrong with the quality of the materials after the sale. This is also the reason for the guarantee given by all manufacturing companies.
On the other hand, the biggest problem found in the free market is that the specifications are not as strict as those applied in factories. This results in different materials being used, which do not last the same period of time.
But also in trade companies there are qualities that, respectively, increase the price. Most battery manufacturers have three grades, giving anyone who wants to buy the best one the opportunity to do so. Many times it is also a matter of marketing, where a company advertises a cheap battery to reach more buyers.
Another factor is the problematic storage of batteries after their production, resulting in them having a shorter life and discharging much more quickly.
We should not forget the tactics of companies to produce consumable products that will last for a certain period of time. For example, a battery that would last for 8 or 10 years would be economically unprofitable for battery companies.
Finally, we should not forget the fact that another reason why batteries do not last a long time is the car itself. The losses in a new car are much less than those in an old car, which may over the years show some electrical loss due to normal wear of some cables or other electrical losses.
Source: RES-EAP
