"Battery memory effect refers to the reversible failure of a battery, that is, the ability to recover after a battery failure. Memory effect refers to the ability of a battery to automatically maintain this specific tendency after enduring a specific working cycle for a long time. This was previously defined in nickel cadmium batteries, where nickel cadmium bag batteries do not have a memory effect, while sintered batteries have a memory effect. However, current nickel metal hydrogen (commonly known as nickel hydrogen) batteries are not bound by this definition of memory effect.".
Due to the improvement of modern nickel cadmium battery technology, the above-mentioned memory effect has been significantly reduced, while another phenomenon has replaced this definition, namely, the "lattice" of nickel based batteries. Generally, nickel cadmium batteries are affected by the combination of these two effects, while nickel hydrogen batteries are only affected by the "lattice" memory effect, and the impact is smaller than that of nickel cadmium batteries.
In practical applications, methods to eliminate memory effects have strict specifications and an operational process. Improper operation can backfire.
For nickel cadmium batteries, the normal maintenance is regular deep discharge: on average, deep discharge is performed once every month of use (or 30 cycles) (discharge to 1.0V/cell, which is called exercise by foreigners). Usually, it is possible to use photovoltaic cells or use shutdown methods to alleviate the formation of memory effects, but this is not exercise, because instruments (such as mobile phones) do not require 1.0V/cell to shut down, and special equipment or lines must be used to complete this work, Fortunately, many NiMH battery chargers have this feature.
For nickel cadmium batteries that have not been exercised for a long time, due to the accumulation of memory effects, it is impossible to use exercise for capacity recovery. At this time, a deeper discharge (called reconditioning by foreigners) is required, which is a process of using a very small current to discharge the battery to 0.4V per cell for a long time, requiring professional equipment to perform.
For nickel hydrogen batteries, the frequency of performing exercises approximately once every three months can effectively alleviate the memory effect. Because the cycle life of nickel hydrogen batteries is far lower than that of nickel cadmium batteries, the method of reconditioning is rarely used.
Recommendation 1: It is unnecessary and harmful to discharge the battery before each charge, as the battery's service life is unnecessarily shortened.
Recommendation 2: It is not advisable to use a resistor to connect the positive and negative electrodes of the battery for discharging. The current cannot be controlled, which can easily exceed 0V, and even cause the polarity of the battery in series to reverse.