<P> There is evidence that the memory effect story originated from orbiting satellites, where they were typically charging for twelve hours out of 24 for several years . After this time, it was found that the capacities of the batteries had declined significantly, but were still fit for use . It is unlikely that this precise repetitive charging (for example, 1,000 charges / discharges with less than 2% variability) could ever be reproduced by individuals using electrical goods . The original paper describing the memory effect was written by GE scientists at their Battery Business Department in Gainesville, Florida, and later retracted by them, but the damage was done . It is unlikely to be a real phenomenon, but has taken on a life of its own as an urban myth . </P> <P> The battery survives thousands of charges / discharges cycles . Also it is possible to lower the memory effect by discharging the battery completely about once a month . This way apparently the battery does not "remember" the point in its charge cycle . </P> <P> An effect with similar symptoms to the memory effect is the so - called voltage depression or lazy battery effect . This results from repeated overcharging; the symptom is that the battery appears to be fully charged but discharges quickly after only a brief period of operation . In rare cases, much of the lost capacity can be recovered by a few deep - discharge cycles, a function often provided by automatic battery chargers . However, this process may reduce the shelf life of the battery . If treated well, a Ni--Cd battery can last for 1,000 cycles or more before its capacity drops below half its original capacity . Many home chargers claim to be "smart chargers" which will shut down and not damage the battery, but this seems to be a common problem . </P> <P> Ni--Cd batteries contain between 6% (for industrial batteries) and 18% (for commercial batteries) cadmium, which is a toxic heavy metal and therefore requires special care during battery disposal . In the United States, part of the battery price is a fee for its proper disposal at the end of its service lifetime . Under the so - called "batteries directive" (2006 / 66 / EC), the sale of consumer Ni--Cd batteries has now been banned within the European Union except for medical use; alarm systems; emergency lighting; and portable power tools . This last category has been banned effective 2016 . Under the same EU directive, used industrial Ni--Cd batteries must be collected by their producers in order to be recycled in dedicated facilities . </P>

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