What factors may increase passivation?
Several different factors may increase passivation thereby influencing the length and depth of voltage delay. They are:
Current capability of cell – High loads on cells may cause voltage delay to increase. Conversely, voltage delay may be unnoticeable with very small loads.
Chemistry– Different variations in chemistry may influence passivation.
Length of storage – Generally, the longer a cell is in storage, the more passivation will grow on the anode surface. Thus, voltage delay may be higher for older cells of a given cell type.
Storage temperature – High storage temperature increases the amount of passivation. Storage of batteries in non-air-conditioned areas during the summer months in hot climates can cause adverse passivation problems. It is recommended that batteries be stored in climate controlled areas.
Discharge temperature – Just as high temperature storage may cause passivation effects, discharging batteries at very low temperatures may cause similar characteristics.
Prior discharge conditions – Partially discharging a cell and then removing the load increases the amount of passivation relative to when the cell was new. Thus, voltage delay on a second run may be more pronounced after the first use of the cell or battery.
In many cases, voltage delay caused by passivation does not affect users of lithium cells. However, we recommend that you evaluate the effect of passivation very carefully when selecting lithium batteries. Users of lithium cells should refer to each cell manufacturer s specific information on this subject.