The battery memory effect refers to the reversible failure of the battery, that is, the performance of the battery that can be recovered after the failure. The memory effect refers to the specific tendency that the battery will automatically maintain after enduring a specific working cycle for a long time This was originally defined in the nickel cadmium battery. The nickel cadmium bag battery does not have memory effect, while the sintered battery has memory effect. The current nickel metal hydrogen (commonly known as nickel hydrogen) battery is not subject to this definition of memory effect

Because of the improvement of modern nickel cadmium battery technology, the above memory effect has been greatly reduced. Another phenomenon replaces this definition, which is 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 application, the method of eliminating memory effect has strict specifications and an operation process. Improper operation will be counterproductive

For nickel cadmium batteries, the normal maintenance is regular deep discharge: on average, one deep discharge (discharge to 1.0V/cell, which is called exercise by foreigners) is carried out every month (or 30 cycles) of use. Usually, the formation of memory effect can be alleviated by means of photocell or power off as much as possible, but this is not exercise, because instruments (such as mobile phones) do not use 1.0V/cell to power off, and special equipment or lines must be used to complete this work, Fortunately, many NiMH battery chargers have this function

For nickel cadmium batteries that have not been executed for a long time, due to the accumulation of memory effects, it is impossible to recover the capacity with exercise. At this time, it requires deeper discharge (foreigners call it condition). This is a process of discharging each battery to 0.4V with a very small current for a long time, which requires professional equipment

For Ni MH battery, execute once every three months can effectively alleviate the memory effect Because the cycle life of nickel metal hydride battery is far lower than that of nickel cadmium battery, the method of second condition is hardly used

Recommendation 1: It is unnecessary and harmful to discharge the battery before each charging, because the service life of the battery is needlessly shortened

Suggestion 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, and it is easy to over discharge to 0V, which may even cause the battery polarity of the series battery pack to reverse