Process Specification For

Process Specification For

EP-WI-014 RevB

Specification for Acceptance Testing of

Commercial Nickel Metal Hydride (NiMH)

and Nickel Cadmium (NiCd) Cells

Engineering Directorate
Energy Systems Division
July 2000

National Aeronautics and
Space Administration
Lyndon B. Johnson Space Center
Houston, Texas

Specification for Acceptance Testing of

Commercial Nickel Metal Hydride (NiMH)

and Nickel Cadmium (NiCd) Cells

Prepared by:
Eric Darcy/EP5
SAFER Battery Lead
Power Systems Branch / Date
Original Signed and Approved by
Thomas L. Davies / EP5
Chief, Power Systems Branch / Date
Vincent D. Watkins
Chief, GFE Assurance Branch / Date
-- / Original version / June 1998
A / 3.2 Relaxed definition of C-rate by inserting an approximated C-rate.
Table 2. Inserted new column for the Sanyo Fat 4/3A NiMH cell. / Sept. 1998
B / 3.2 Added NiCd cell treatment and internal resistance measurement and criteria.
Table 1. Changed charge rate and duration for NiMH cells for step 4.
3.5 Deleted recording required.
3.6 Deleted recording required.
4.0 Added plots and cell drawing to report.
Table 2. Inserted three new rows for two Sanyo NiCd cells and one Sanyo NiMH cell. / July 2000


This document defines how a lot of commercial nickel metal hydride (NiMH) and nickel cadmium (NiCd) cells are accepted and certified for assembly into flight batteries for NASA. This specification is written is accordance with JSC SLP 4.6 “Procurement”. TwoSix cell designs are included in this document in Table 2. The contractor shall procure all cells, serialize them, cycle test them, perform leak checks, re-sleeve them, perform mass and dimensional checks, and deliver them to a NASA-designated site.


The contractor shall procure all cells and obtain a certificate of compliance and material safety data sheet from the source.


The following tests shall be performed on every cell. Failure on any test or measurement for which pass/fail criteria are given shall result in rejection of the non-conforming cell. Failure of rates exceeding 15% of lot shall constitute failure of the entire lot unless written exception is made by NASA-JSC. Equipment measuring voltages, temperature, and mass shall be calibrated with equipment traceable to a national standard.


Once received, all cells shall be stripped of their insulating sleeves, washed as necessary to remove traces of electrolyte residue, and serialized.

CAUTION: Stripped cells should be handled very carefully and be stored in isolating trays or equivalent fixtures.


The contractor shall cycle each cell according to Table 1. The C-rate shall be approximately based on the manufacturers rated capacity. Note step 1 can omitted if a cell OCV is less than 1.2V.

For NiCd cells, the charge process of step 4 must begin with the cells soaked at 0 C and be completed in a thermal environment convectively controlled to 0 C (-10 C for the high rate subC cell). This procedure will cause high oxygen pressure build-up in the cells because the oxygen recombination kinetics of the cell will be reduced. Allow cells to reach to ambient temperatures before moving on to step 3.

For NiMH cells, the charge process of step 4 is done in an environment at 25  2 C and ambient pressures.

During step 5, thea 100 ms current pulses shall be interrupt the constant current discharge after 30 minute into the discharge. The pulse step shall be at 10C for cells intended for high power density applications and at C/10 for cells intended for high energy density applications. The internal resistance of the cell, Re, shall determined by Re = V/I. For high rate applications, reject any cell with an Re that is 15% above the average value for the lot.

Allow cells to return to ambient before resuming cycling with step 3 and 5. Reject any cell not meeting the capacity criteria of Table 2 on step 5.

Table 1. Capacity Cycling

Step / Type / Current / Duration
1 / Discharge / 1C / to 1V/cell
2 / Charge / C/10 / 16 hours
3 / Discharge / 1CC 1C / to 1V/cell
4 / Charge / C/3 for NiMH
C/10 for NiCd / 210 min for NiMH
16 hours for NiCd
5 / Discharge / 1C / to 1V/cell


The contractor shall verify each cell for KOH leaks with phenolphthalein around the crimp seal and seal vent areas. Reject any cell testing positive for leaks.


The contractor shall refinish the cells with an exterior teflon insulative washer inside the new sleeve according to his cell drawing.

3.5 MASS

The contractor shall weigh each cell to within  1 mg. Reject any cell outside the range defined in Table 2.


Diameter and height of each sleeved cell shall be within the tolerances

shown in table 2. The diameter shall be measured at the maximum point

along the length of the cell. The height shall be measured along the

central axis of the cell at the maximum point. Reject any cells outside the ranges specified in table 2.


Perform a visual inspection of each cell and remove any cell with defects in its sleeving or labeling. Pass/Fail: Damage to a degree which is deemed more than superficial from a mechanical or electrical insulating standpoint.


For each lot subjected to the acceptance tests described herein, a report shall required provided the tabulated results of all tests. A charge/discharge plot of three typical cells during steps 4 and 5 of section 3.2. The contractor’s cell drawings shall also be included in the report.

Table 2. Pass/Fail Criteria

Cell P/N / mass (g) / length (mm) / diameter (mm) / capacity (Ah)
TH3500SRI-01 / 52.0  2.0 / 67.00 +0.00, -1.00 / 17.00 +0.00, -0.70 / 3.000 min
HR4/3FAUSRI-01 / 60.0  2.0 / 67.00 +0.00, -1.00 / 18.00 +0.00, -0.70 / 3.300 min
HHR210SRI-02 / 38.0  2.0 / 50.00 +0.00, -1.50 / 16.80 +0.00, -0.70 / 1.600 min
N-1900SCR / 5456.0  2.0 / 43.00 +0.00, -1.50 / 23.00 +0.00, -0.70 / 1.500 min
KR-1400AE / 31.0  2.0 / 50.00 +0.00, -1.50 / 17.00 +0.00, -0.70 / 1.100 min
HR4/3AUXSRI-01 / 5255.0  2.0 / 67.00 +0.00, -1.00 / 17.00 +0.00, -0.70 / 3.000 min


JSC SLP 4.6Procurement

JSC SLP 4.20Statistical Techniques

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