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Task 8.1 – Reconditioning of cells underperforming discharge capacity requirements
OPERATING INSTRUCTION AND TECHNICAL REQUIREMENTS (TR) INSTRUCTIONS / EVIDENCE WHEN DEVIATIONS FROM TR
Note:
For charged batteries from service containing cells returning less than
80% of its nominal capacity output, this reconditioning is advised. Prior
to any ultimate costly replacement of cells, it should be proven that
the reason for failing the requirement is not caused by a reversible
capacity loss. (compare section 1.5.8) In most cases one cycle
consisting of deep discharge, recharge and capacity test would be
sufficient to meet the capacity requirement. Two cycles can be carried
out to proof the reproducibility of cell’s performance. If no improvement
in capacity output relative to the previous measurement(s) could be
achieved the cells are irreversibly aged and shall be replaced.
1. Deep discharge the cells
When the battery is discharged at rates between 0.2*I
1
and I
1
to
20 V connect 1 ohm/2 watt resistors for 24 hours up to 72 hours
between the positive and the negative terminal of each cell. If no
resistors are available, discharge the battery at 0.1*I
1
to 0.5V per cell
and store the battery for 4 hours (minimum.)
2. Remove the resistor and charge the battery for 8 hours at 0.2*I
1
as shown in Appendix 2. If necessary, adjust the electrolyte level
of the cells 10 to 15 minutes prior to the end of charge.
Measure and record the cell voltages prior to the end of charge.
3. Stand the battery for 1 hour.
4. Discharge the 24V battery at I
1
to 20V.
Requirement: The voltage of each cell after 48 minutes must
be equal / greater than 1 Volt
Note: If the discharge at the I
1
rate is not feasible, select
a different rate and criteria from the table below.
Record the cell voltages at the corresponding time indicated in
column 2 in the log book.
5. Soak the battery to room temperature, which can take up to 8
hours.
8.Sub-Tasks of maintenance / commissioning
procedures
Discharge current rate Time (min) cell voltage
reading
Voltage requirement
for cells (V)
0.2*I
1
240 ≥1.0
0.4*I
1
120 ≥1.0
0.6*I
1
80 ≥1.0
0.8*I
1
60 ≥1.0
I
1
48 ≥1.0
The document reference is online, please check the correspondence between the online documentation and the printed version.
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