WHAT IS THE “MEMORY EFFECT”?
Memory Effect affects the run time of a traditional (NiCd) Nickel Cadmium Rechargeable Battery. There is some misconception about the word “memory”. Memory is commonly blamed for just about any battery failure known to man. The word ”memory” is derived from “cyclic memory”, meaning that a NiCd battery could remember how much discharge was required on previous discharges and then fail to regain a full capacity recharge. Improvements in battery technology have virtually eliminated this phenomenon. The problem with the modern NiCd battery is not the cyclic memory but the effects of large crystalline formation. (When we refer to memory, we are referring to the formation of crystals.) The active materials (nickel & cadmium) of a NiCd battery are present in crystalline form. When the memory Phenomenon occurs, these crystals grow, forming spike or tree-like crystals that cause the NiCd to gradually lose performance and shut off early . In advanced stages, these crystals may puncture the separator, causing high self-discharge or an electrical short. Crystalline formation only presents a problem if the battery is repeatedly recharged without a periodic full discharge. It is not necessary to discharge a NiCd before each charge. A full discharge to one volt per cell once a month is sufficient to keep the crystal formation under control. Such a discharge/charge cycle is commonly referred to as “exercise”.
If no exercise is applied for several months, the crystals engrain themselves, making it more difficult to dissolve. In such a case, exercise is no longer effective in restoring a battery and “recondition” is required. Recondition is a slow, deep discharge that drains the cell to a voltage threshold below one volt must be discharged to at least 0.6 volts per cell to dissolve the more resistive crystalline build-up. If you use NiCd batteries you should purchase a charger with a "conditioning" function to neutralize the crystalline build-up problem.
Not all NiCd batteries respond well to recondition. A battery that has been in service for over a year and had not been exercised regularly may have a capacity reading that dropped to a low 20%. Even with repeated recondition cycles, the battery may not improve to an acceptable capacity
Nimh Rechargeable Batteries have almost no Memory Effect. Nimh have a different internal chemistry and are not as susceptible to the same “memory” problems as NiCds. In fact Nimh batteries can and should be charged from any discharge state. This is a major advantage of Nimh batteries over NiCd.
什么是“记忆效应”？
记忆效应影响了镉镍二次电池的放电时间。关于“记忆”一词，存在一些误解。“记忆”源自于“循环记忆”，它意味着镉镍电池能够记住先前的放电量，不能再次充电到最大容量。电池技术的提高正逐渐消除这种现象。 现代镉镍电池的问题不在于循环记忆，而在于大量结晶结构的影响。（当我们提到记忆效应的时候，我们将会提到结晶结构。）镉镍电池里的活性物质镍和镉都表现为晶体形式。当记忆效应发生时，晶体会增长，形成刺钉状或树状结晶，这导致了镍，镉逐渐失去其原有功能。进一步的反应，这些晶体可能穿过分离器，导致高的自放电或者短路。如果电池在没有完全周期性放电的情况下就被反复充电，就会导致结晶的形成。对于镉镍电池来讲，每次充电前的放电是不必要的。每个月每个电芯完全放电到一伏足以保持水晶结构在控制之下。像那样的充放电循环通常被称之为“exercise”。如果几个月都不"exercise"，结晶将会再次集结，并且使之溶解将更加困难。 在那种情况下，"exercise"在重储和恢复电池方面将不起作用。恢复是一种缓慢的，深度的放电过程，它放电使电芯达到一个电压极限，一个电芯一定要由一伏的电压至少放电至0.6伏以下，才能溶散更多的抗性晶体。 如果你使用镉镍电池，就应该买一个带有压制形成结晶功能的充电器。 并非所有的镉镍电池都有一个好的恢复反应。一个用了一年以上且不被经常循环的电池，容量将下降到20%以下。这时即使多次重复恢复循环，电池也不会提高可接受的容量。镍氢二次电池几乎不受记忆效应的影响。它的的内部化学结构使之不像镉镍电池一样遭受记忆效应的影响。事实上镍氢电池在任何放电状态下都可以进行再充电。这是镍氢电池优于镉镍电池的一个主要的优势。