Alber Cellcorder CRT-300, Руководство пользователя

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Application Note CC-001
78
METALLIC RESISTANCE
This portion of the internal conduction path troubles most battery test
experts. It is here that deterioration of a cell can occur most rapidly and
then will often go undetected between the yearly integrity tests or, even
less frequently, the capacity tests.
The tear down of failed batteries with abnormal internal resistances has
proven that the terminal posts and the internal straps and grids are most
often the victims of corrosion, poor welds or "burns."
7 Where found, con-
tact surfaces of a copper insert can corrode or loosen from its
surrounding lead post. The Cellcorder easily detects these types of
problems.
Fig. 5 clearly shows the loss of capacity due to a high internal
metallic
resistance. The available voltage at the battery’s terminals is reduced
from the start of the discharge and continues to the end.
ELECTROCHEMICAL RESISTANCE
Cell paste, electrolyte and separators form the electrochemical part of cell
internal resistance. Long-term increases in R
ELECTROCHEMICAL
can be caused
by loss of active material or paste due to aging. Short-term changes also
occur naturally during parts of the charge or discharge processes when
the specific gravity is altered; or when the contents of the separators
varies and/or the chemical composition of the surfaces change.
Separator compression, clogging or shorts, and conditions like sulfation
are frequently causes of abnormal, increased electrochemical resistance;
however,
accelerated electrolyte dryout appears to be public enemy #1
when it comes to VRLA failures.