The cost of lithium batteries used to power electric vehicles has fallen markedly in recent years, but they can still account for up to a third of the price of an electric car. Car owners’ concerns about the durability of traction batteries are intended to be tempered by a new study by American scientists.
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Researchers at Stanford University have found that the actual operating conditions of most electric vehicles affect the life of traction batteries not quite as their developers predicted, based on the results of laboratory tests. Load test cycles do not reduce the service life of traction batteries quite as much as the modified test methodology proposed by Stanford scientists showed.
They argue that the irregular rhythm of electric vehicles in city traffic, short trips alternating with long stops, and even periodic sharp accelerations actually affect the service life of traction batteries much more favorably than previously thought. When electric vehicles are used by private individuals in urban environments, traction batteries can last 40% longer than previously expected.
Moreover, even short sharp accelerations, which provoke a rapid release of charge from traction batteries, actually increase their resource, and do not have a detrimental effect on it, as was previously thought. The authors of the study tested 92 samples of commercially produced lithium-ion traction batteries for two years using load and charging profiles close to the conditions for using electric vehicles in the city.
Previous methods of more uniform loading and charging are capable of simulating the operation of commercial electric vehicles; to some extent, they make it possible to predict the life of traction batteries during intensive use, but for private owners, the main enemy of batteries is not the number of charging and discharging cycles, but time itself. The results obtained during the study can be taken into account when developing control software for power systems of electric vehicles. The resulting charging and discharging profiles can seriously affect the service life of batteries.