How to restore and prolong nickel-based batteries

A common difficulty with portable equipment is the gradual decline in battery performance after the first year of service. Although fully charged, the battery finally regresses to a point where the available energy is less than half of its original capacity.
Rechargeable batteries are known to cause more concern, grief and frustration than any other part of a portable device. Given its comparatively short life span, the battery is also one of the costliest and least reliable parts. In plenty of ways, a battery exhibits human-like characteristics: it needs nice nutrition, prefers moderate room temperature and with the nickel-based process, requires regular exercise to prevent the phenomenon called memory.
How to restore and prolong nickel-based batteries

When nickel-based batteries are mentioned, the word memory comes to mind. Memory was originally derived from cyclic memory, meaning that a Nickel-cadmium (NiCd) dell laptop battery replacement could keep in mind how much energy was necessary and would provide similar amounts on later discharges. Improvements in battery technology have virtually eliminated this phenomenon. The modern term of memory is a crystalline formation that robs the battery of its capacity. Applying one or several full discharge cycles can often reverse this effect.
The active cadmium material of a NiCd battery is present in finely divided crystals. In a nice cell, these crystals stay small, obtaining maximum surface area. Memory causes the crystals to grow, reducing the surface area. In advanced stages, the sharp edges of the crystals may penetrate the separator, initiating high self-discharge or an electrical short.
The effect of crystalline formation is most visible if a NiCd battery is left in the charger for days, or if repeatedly recharged without a periodic full discharge. Since most applications do not use up all energy before recharge, a periodic discharge to 1V/cell (known as exercise) is essential to prevent memory.
All NiCd batteries in regular use and on standby mode (sitting in a charger for operational readiness) ought to be exercised three times per month. Between these every month exercise cycles, no further service is necessary and the battery can be used with any desired user pattern without memory concern.
If no exercise is applied to a NiCd for three months or more, the crystals ingrain themselves, making them more difficult to break up. In such a case, exercise may no longer be effective in restoring a battery and reconditioning is necessary. Recondition is a secondary discharge that slowly removes the remaining battery energy by draining the cells to virtually zero volts. NiCd batteries can tolerate a small amount of cell reversal. In the work of deep discharge, caution must be applied to stay within the allowable current limit to minimize cell reversal.