Alber Cellcorder CRT-300, Руководство пользователя

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Application Note CC-001
83
The fantasy begins with the battery’s installation. An acceptance capacity
test is conducted and the cells’ internal resistances measured. The results
should be fairly uniform and he would safeguard this data. He knows it
serves as the ideal baseline, or “reference” per IEEE/ANSI P-1188, for
future internal resistance tests. He will then be able to make
cut and dry
decisions about maintenance or cell replacement.
Unfortunately, it's a fantasy in most environments because, in the rush
and tumult of getting a facility on-line, establishing a baseline usually has
low priority. As a result, we are then left to getting data in the best ways
possible.
The second best time to obtain a set of data is shortly after capacities
have been determined on
the same model cells of the same age . Lastly,
try obtaining data on the same model cells of any age. Over time, data to
the end-life or 80% capacity level will be accumulated.
-CAUTION-
Internal resistance data taken without the benefit of correlated
known capacities is often referred to as “as-found comparative
values.” This as-found data could be used to set a baseline, but be
very cautious . It is not unusual to find an entire string of cells of
uniform internal resistances, and normal appearance on float, but
with
failing capacities . In this situation, we highly recommend at
least a crude service/load test be performed to lend some credence to
the internal resistance measurements.
THE COURSE OF ACTION
If you do not have end-life or 80% baselines developed from significant
samples of the same cells, age, etc., you should use the following rough
rules-of-thumb based upon Cellcorder user reports and in-house
experience.
If the internal resistance is:
20%-50% above the 100% baseline, then the cell be load tested . . . the
sooner the better if it’s towards the high end;
at 50% or above the baseline, the cell be replaced.
Surprisingly, the IEEE/ANSI VRLA P-1188 proposed standard is more
liberal in this matter. It recommends that from 25% to about 43%, the
cell’s manufacturer be contacted. Above 43%, a load test be done ASAP.
Actually, the standard is expressed in the reciprocal of internal resistance,
conductance (
mhos .)