NiCd Battery Crystalline FormationMarch 26th Fact-of-the-Day
Newly manufactured NiCd battery cells contain finely-divided crystals of nickel and cadmium. Small crystal size is important to good cell performance, because small crystals expose larger total surface areas than do large crystals. The crystals remain small so long as NiCd cells continue to have good performance. Frequently-repeated cycles of near-total-discharge followed by total-recharge help considerably to keep the crystal sizes small. If instead NiCd batteries are kept in a charger for long periods of time, are allowed to remain discharged for long periods of time, or are repeatedly recharged before being near-fully-discharged, the crystal sizes grow. That greatly reduces their total surface areas and dramatically reduces cell performance. Sometimes the crystals even grow large enough to penetrate through the polarity separator, causing a short circuit. ©2005 Martek International All rights reserved.
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