||NAVSO P-3676: Navy Primary and Secondary Batteries
6.4 Manufacturing and Quality Assistance
All cell manufacturers produce electrodes
in-house or very carefully control the production of this key cell component.
Methods of active material addition to the substrate and current collector can
be combined into five major methods. These methods of plate preparation are
listed in Table 6-3. All substrates, grids, current collectors, and tabs
should be solvent cleaned to remove all traces of grease or oil in order to
provide adhesion contact with active materials.
METHODS OF PLATE PREPARATION
Chemical and Electromechanical
Chemical and electromechanical impregnation
in sintered nickel powder plaque or fiber material.
Application of a wet paste of active material with or without
a binder onto a conductive
followed by compaction and drying.
dry active material blended with or without a conductiver powder,
onto a supporting
current collector. (Pocket Plates
are a particular version or pressed powder plates.)
materials and polymeric binder are formed into a sheet which is then
pressed onto an
A spongy deposit of cadmium metal and sometimes
co-deposited cadmium hydroxide is caused to
deposit on a
metallic collector/support substrate by means of passage of electrical
Once the plates are completed and accepted they are stored
in a carbon dioxide free environment until needed for cell assembly. Plates
may be stored for an indefinite period provided the environment is
Cell assembly starts with a pack of positives, negatives, and
separator. Depending on the type of construction, these components are
interleaved to form a plate pack and are assembled with a terminal/current
collector. The assembly is placed into a container (with an insulator in metal
cans) and a cover is placed over the assembly.
The overall cell assembly, with control
points, is illustrated in Figure
4-1 for rectangular cell production. With minor variations, assembly of
most cells contains the same operations. Plastic cell containers introduce
some variations in materials and sealing processes. Plastic cell container
materials and sealing processes are summarized in Table
TABLE 6-4. PLASTIC CELL
CONTAINER MATERIALS &
NYLON (presently required for aircraft
- Solvent welded (phenol solvent)
welded (includes ultrasonic
Modern designs tend toward thermal
STYRENE AND ACRYLONITRILE
- Solvent weld
- Thermal weld
- Thermal weld
- Solvent weld
A battery may consist of multiple interconnected cells with
container, insulation, monitoring devices, connectors, heaters, hold downs,
pressure relief valves, special thermal control paint, fuses, current monitor,
integral charger, and any other unique features as needed.
Minimum Quality System Inspection Requirements
For a discussion of quality control issues
relevant to all batteries refer to Section 4.4
Order Review System : An order review system should be in place
to insure that a customer's needs are met and that any requirements for
special processes, test equipment, tooling, fixtures, and skills (e.g.
soldering) are met.
Qualified Vendor List : Materials and parts should be purchased
from vendors who have been qualified by the cell manufacturers. Vendor
qualification status should constantly be evaluated by a supplier performance
rating derived from incoming inspection results.
Raw Materials (Chemicals) : Lots of incoming raw materials should
be sampled and inspected for compliance with cell manufacturer and/or supplier
specifications for chemical purity and physical characteristics.
Molded Plastic Parts : Incoming inspection should confirm: (a)
material; (b) cleanliness, freedom from trash; (c) freedom from bubbles,
voids, and cracks; (d) conformance to the part drawing.
Metal Parts and Plated Metal Parts : Incoming inspection should
confirm: (a) material; (b) conformance to part drawing dimensions; (c) plating
material thickness and integrity (when plating is required).
Thermostats, Thermistors, Heaters, and
Relays : 100% testing for
operating characteristics versus temperature is necessary.
Wire: Inspection should confirm insulation type and thickness,
wire gauge, wire strand count, and color.
Rubber and Elastomeric Components : Caustic resistance,
durometer, and composition as well as dimensional requirements should be
confirmed by Incoming Inspectors.
Connectors: Conformance to drawing and Military Specification
requirements should be confirmed via Certificate of Compliance (C of C).
Separator Materials : Material, weight/unit area, thread count
(for woven materials), wettability, absorption of electrolyte, and specific
resistance must be confirmed by Incoming Inspection.
Electrode Fabrication Controls and Inspection
Statistical Process Control: Statistical Process Control should
be applied using the data gathered. All processes should be continuously or
frequently monitored for the applicable critical parameters:
Atmosphere (if any special atmosphere required)
Process flow rates
Co, Mg in all process
solutions and wash water
Fe, Cu in nitrate
Inspections: Frequent measurement of at least these critical
parameters should be made:
Electrode Preparation Process
Using a sampling plan, electrodes should be inspected for
dimensional conformance to applicable drawings, freedom from visual defects,
edge quality (no sharp protrusions), and overall physical integrity.
Where used, tab stock should conform to drawing requirements.
Tab attachments, welding, or staking, should be inspected for the quality of
the attachment. For example, weld nuggets for welded tabs should meet criteria
specified by the cell manufacturers.
Inspection should address all critical cell assembly
Proper separator in
Terminal to plate attachment (or plate
group) sound and in compliance with design
Electrolyte fill level and concentration in accordance with design
The cell seal should be inspected by the appropriate method.
Cell dimensions after sealing should conform to the design specification (cell
Safety Vent Release Pressure (Where Used)
Safety vents should be inspected for conformance to the
allowable release pressure range. The frequency of inspection is determined by
the nature of the safety vent and the end use. For high reliability (eg.
aerospace), 100% of the vents must be tested.
Quality control should confirm:
That parts required by the Bill of
Materials are available in the battery assembly area
That assembled batteries contain all of
and only the parts listed on the Bill of Materials
That the battery assembly is in
accordance with the assembly drawing, that is, each part is in the proper
That all intercell connections have been
properly made and torqued
That all wiring, if any, is properly and
That all electrical components (heaters,
thermostats, thermistors, and relays) are properly located and properly
wired to the connector (pin to pin or socket to socket) in conformance with
the applicable wiring diagram
That battery and component marking meet
requirements of the battery assembly drawing and the applicable procurement
That battery dimensions and weight are
within drawing and contract requirements
That electrolyte fill level and
concentration are within specification requirements
That the battery is visually clean.