What is the memory effect?
Memory effect only happens on Ni-Cd batteries. As in traditional technology a Ni-Cd battery's negative is agglomeration with thick Ni crystal, if Ni-Cd batteries are recharged before they have been fully discharged, Ni crystal easily gathers to form agglomeration, which makes the primary discharge platform come into being. The battery stores the platform, which will be considered as the end of discharge for the next cycle even though the capacity decides that the battery can be discharged to a lower platform. The battery will store this process in its memory so during the next discharge, the battery only remembers this reduced capacity. Similarly any further incomplete discharge in each use will aggravate the effect makes lower capacity. The effect there are two methods to remove the effect: firstly deep discharge at trickle current (i.e. 0.1C to 0V), secondly several cycles at high currents (e.g. 1C).
What is the ambient temperature affects the battery performance?
Low temperatures (e.g. -15?) will obviously reduce Ni-Cd and Ni-MH battery discharge rate. At -20? electrolyte is at its freezing point, charge speed will greatly slow down. At low temperature (under -15?) charge will raise the internal gas pressure and probably unseal the safety vent. Ambient temperature of 5?to 30? is the best range to get effective charge. Generally with temperature rising charge efficiency will become higher. But when the temperature rises to 45? or higher, the materials performance in the battery will be degenerated and battery service life will be shorten greatly.
What is battery inner impedance?
Battery impedance is the resistance when the current flow through an operating cell, in general the internal resistance is included both d.c. and a.c. resistance. For the rechargeable cell resistance is small and electrode is easy to be polarized along with producing a polarization resistance while measure d.c. resistance, the accurate value can't be measured.