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。