The calendar-life determines how long a battery may last on a shelf, unused, before becoming useless. It is temperature dependent since hotter temperatures hasten degradation. Keep in mind that this differs from activated stand life or shelf life, which is the amount of time it takes for a battery to lose some of its charge but not die.
Calendar life and cycle life are two common words used to describe battery life. A battery’s calendar-life is the period of time during which it may be kept idle or little used and still have its capacity exceed 80% of its initial value. The number of full charge-discharge cycles a battery may go through before losing 80% of its initial capacity is known as cycle life.
Cycle life and calendar-life are not mutually exclusive. The remaining calendar life is reduced as the number of battery cycles used increases, and a battery that has been stored for a long time has fewer charging cycles. Because the chemical makeup of the battery’s cell determines how long it will last.
The life of a battery is impacted by the gradual deterioration of the electrodes and electrolytes, a reduction in the amount of active material present in the battery, or a restriction on access to active material. Whether a battery is being stored or going through a charge-discharge cycle, it continues to deteriorate over time. The possible calendar-life or cycle life is determined by the rate of this degradation.
What factors affect calendar life?
The growth of a passivation layer on the negative electrodes is the primary cause of battery calendar ageing. Film formation on the positive and negative electrodes is the primary ageing mechanism. The state of charge (SOC) at which a battery is stored has an impact on the calendar life of the battery.
The battery chemistry under consideration will determine how SOC affects calendar life. For optimum calendar life, lead acid batteries must be stored at full charge. While Nickel-based and Lithium-ion batteries must be stored at 40% of their full SOC.
The life of the calendar is also impacted by the storage temperature of the batteries. The rate of a reaction rises with temperature. This accelerates the rate of undesirable chemical reactions, which also accelerates battery deterioration. The battery’s calendar life is negatively impacted by higher temperatures.
Also Read: What is Battery Life?
What is the time comparison of calendar life and cycle life of a battery?
By determining the period of time required for a battery’s cycle life to be fully utilized, it is possible to compare cycle life and calendar life more effectively. Life should be portrayed in terms of time, just as the calendar gives life in terms of time cycles. A lithium ion battery has cycle life of about 1200 cycles, but it is rarely fully charged and discharged. It is typically charged to 90% of its maximum capacity and discharged to 10% to 15% of that capacity.
