Nickel strip is a widely used metal interconnection material for cylindrical battery pack assembly, battery cell welding, electrical connections, and compact energy storage systems. In battery manufacturing, nickel strip is commonly positioned between individual cylindrical cells and connected by resistance spot welding. Depending on the electrical, mechanical, cost, and welding requirements of the application, the strip may be produced from commercially pure nickel or from low carbon steel with a nickel plated surface.
For battery welding applications, the selection of nickel strip involves more than simply choosing a material called “nickel.” Strip thickness, width, electrical resistance, weldability, mechanical strength, surface condition, cell arrangement, welding equipment, and required current capacity all influence the suitability of the interconnection.
Common cylindrical battery formats include 18650 and 21700 cells. Nominally, an 18650 cell is approximately 18 mm in diameter and 65 mm long, while a 21700 cell is approximately 21 mm in diameter and 70 mm long. Actual dimensions can vary between cell designs and manufacturers, so battery pack designers should verify the actual cell dimensions before selecting a punched nickel strip or determining the strip pitch.
This guide explains nickel strip for battery welding applications from the perspectives of material selection, electrical connection, spot welding, strip dimensions, punched tab design, center distance, battery pack assembly, manufacturing forms, quality considerations, and practical design requirements.
Nickel strip for battery welding is a thin, flat metal strip designed to electrically connect battery cells and provide a weldable pathway between individual cells.
In cylindrical lithium battery packs, the strip is normally placed across the terminals of several cells. A resistance spot welding machine applies controlled electrical current through welding electrodes. The resulting localized heat creates a weld between the strip and the cell terminal without requiring the entire cell terminal or the entire strip to be heated.
Nickel strip is especially useful because it combines electrical conductivity, corrosion resistance, mechanical flexibility, and suitable resistance welding characteristics. Commercially pure nickel can provide a relatively low-resistance electrical path and strong corrosion resistance. Nickel plated steel, meanwhile, can provide a practical balance between mechanical strength, cost, and welding performance.
The final battery interconnection may be manufactured as:
Continuous nickel strip
Nickel strip coil
Cut nickel strip
Pre-cut battery tabs
Punched nickel strip
Stamped nickel tabs
Custom battery connectors
Series connection strips
Parallel connection strips
Multi-cell interconnection pieces
Custom battery pack connector components
The appropriate format depends on the battery pack structure and assembly process.
Battery packs containing multiple cylindrical cells need a reliable electrical connection between cells. Individual cells may be arranged in series, parallel, or a combination of both.
A series connection increases the total pack voltage, while a parallel connection increases the available capacity and current capability of the battery assembly. The metal interconnection must therefore carry current between cells while remaining mechanically stable.
Nickel strip provides several practical advantages.
The interconnection material must conduct current with limited electrical loss. The resistance of the connection depends on the material, strip dimensions, connection length, weld quality, and contact conditions.
Pure nickel is commonly selected where electrical performance is important. Nickel plated steel can also be used in many standard battery pack applications where the electrical requirements are compatible with the strip design.
Nickel and nickel plated materials can be processed using resistance spot welding equipment designed for battery assembly.
Spot welding is widely used because the welding energy can be concentrated in a small area. This helps minimize unnecessary heating of the surrounding components when the welding process is properly controlled.
Resistance spot welding is also compatible with automated and semi-automated battery assembly processes. Industrial resistance welding specifications can require process verification, weld inspection, and mechanical testing of representative welds. NASA's published resistance spot welding process specification, for example, describes qualification and verification procedures for battery and electronic assemblies.
Nickel has good corrosion resistance compared with many common structural metals. This characteristic is useful for battery interconnections because the connection must remain stable throughout the intended service life of the battery assembly.
For nickel plated steel, the nickel coating provides the surface characteristics associated with the plated material while the steel substrate contributes mechanical strength and can reduce material cost.
Thin strip can be bent, formed, punched, or cut according to battery pack requirements.
This is particularly useful when cells are arranged in complex patterns or when a battery pack requires a customized connection path.
Nickel strip can be supplied in coils for continuous processing or as individual pieces for manual and automated assembly.
Coil material is suitable for:
Slitting
Cutting
Punching
Stamping
Progressive forming
Automated feeding
Custom tab production
Pre-punched and pre-stamped nickel strips can reduce manual positioning during battery pack assembly.
Two major categories are commonly considered for battery connection strips: pure nickel and nickel plated steel.
Pure nickel strip is produced primarily from nickel rather than a steel substrate with a nickel coating.
Common commercial grades include Nickel 200 and Nickel 201. Pure nickel strip is widely used for applications where electrical conductivity, corrosion resistance, and predictable welding behavior are important.
Pure nickel is often selected for:
High-current battery packs
Energy storage assemblies
Power tool battery packs
Electric mobility battery packs
Custom lithium battery packs
Industrial battery systems
Battery prototypes
Applications where the strip material itself must have good nickel characteristics
Material specifications should always be verified against the actual grade and supplier documentation. A product described as “pure nickel” should not automatically be assumed to have a particular nickel grade or exact purity without a material certificate.
Nickel plated steel strip consists of a low carbon steel substrate with a nickel plated surface.
SPCC is commonly used as a low carbon cold rolled steel substrate for this type of material.
The steel substrate provides mechanical strength and can make the material more economical than a solid nickel strip. The nickel surface provides a nickel-based protective and conductive surface suitable for many battery connection applications.
Nickel plated steel is commonly considered for:
Standard cylindrical battery packs
18650 battery assemblies
21700 battery assemblies
DIY battery packs
Consumer battery products
General battery connection applications
Cost-sensitive battery pack designs
The final selection should be based on the required current, weldability, mechanical requirements, and battery design rather than material name alone.
Pure nickel and nickel plated steel should not be treated as identical materials.
Pure nickel is a homogeneous nickel material throughout the strip thickness. Nickel plated steel contains a steel core and a nickel surface layer.
This difference affects electrical resistance, mechanical characteristics, weight, cost, welding behavior, and forming performance.
For higher electrical performance requirements, pure nickel may be preferred. For standard battery pack construction where cost and mechanical strength are important, nickel plated steel can be a practical option.
The decision should be made based on actual current requirements and measured connection performance.
A common mistake in battery assembly is choosing strip thickness based only on physical appearance. A thicker strip is not automatically the best strip. The electrical resistance, material composition, strip width, connection length, weld configuration, and number of parallel current paths should all be considered.
The 18650 cylindrical cell has a nominal diameter of approximately 18 mm and a nominal length of approximately 65 mm. Actual dimensions vary between cell models.
18650 cells are commonly arranged into battery packs for:
Portable electronics
Power tools
Lighting equipment
Robotics
Portable power systems
Battery backup systems
DIY battery packs
Energy storage equipment
Mobility applications
Nickel strip can connect adjacent 18650 cells through spot welded tabs.
For an 18650 battery pack, the strip layout must correspond to the actual cell holder, cell diameter, spacing, insulation thickness, and welding electrode position.
The pitch of a punched nickel strip is particularly important when the strip has multiple holes or tabs corresponding to several cells.
The 21700 cylindrical cell has a nominal diameter of approximately 21 mm and a nominal length of approximately 70 mm. Actual dimensions may vary depending on the cell design.
The larger cylindrical format provides more internal volume than the 18650 format. Research comparing commercial cylindrical cells has shown that actual measured dimensions can differ from nominal format values, which is important when designing close-tolerance battery holders and interconnection strips.
21700 battery packs can use nickel strip for:
Series connections
Parallel connections
Multi-cell modules
Energy storage systems
Power tool packs
Electric mobility systems
Portable power products
Custom battery assemblies
Because the cell diameter is larger than that of an 18650 cell, the required strip pitch is generally different.
For punched nickel strip, center distance, also called pitch, defines the distance between corresponding cell positions or connection centers.
The following reference is based on the supplied application information and is intended as a practical design reference. It should be verified against the actual cell dimensions, holder dimensions, insulation thickness, and battery pack structure before production.
| Center Distance Pitch | Applicable Cell | Application Scenario |
|---|---|---|
| 18.5 mm | 18650 | Rackless arrangement, tight cell spacing |
| 19.0 mm | 18650 | Compatible with 18650 plastic battery holder, standard slot |
| 19.5 mm | 18650 | With thicker holder or insulation paper gap, used by some factories |
| 21.5 mm | 21700 | Rackless arrangement, 21700 diameter approximately 21 mm |
| 21.8 mm | 21700 | 21700 bare arrangement with small clearance, used by some standard factories |
| 22.5 mm | 21700 | Compatible with 21700 plastic battery holder, standard slot |
The values above should be treated as design references rather than universal standards. Cylindrical cell dimensions can vary, and battery holders, Insulation Materials, cell wraps, and manufacturing tolerances can change the required center distance.
Pitch is one of the most important dimensions for punched battery strips.
A strip with an incorrect pitch may not align with the cell terminals or the battery holder.
For example, a strip designed for a 19.0 mm center distance should not automatically be used for a pack designed around a 19.5 mm cell spacing.
The difference may appear small, but when many cells are arranged in a long row, small dimensional differences can accumulate.
A battery pack with ten connection positions can amplify a small pitch mismatch across the complete strip.
Therefore, pitch should be evaluated together with:
Cell diameter
Cell holder design
Cell spacing
Insulation thickness
Cell wrap thickness
Strip width
Strip hole diameter
Welding electrode spacing
Battery enclosure dimensions
Manufacturing tolerance
A rackless battery arrangement places cylindrical cells close to one another without a conventional plastic cell holder.
This configuration can reduce package size, but it requires careful control of cell spacing and insulation.
For 18650 cells, a center distance such as 18.5 mm may be used in certain close-spacing arrangements.
For 21700 cells, a center distance such as 21.5 mm may be used for close arrangements.
However, these values should not be interpreted as universal requirements.
The actual cell diameter, protective wrapping, insulation sheet, adhesive material, and assembly tolerance must be considered.
A close-spacing design should also provide sufficient electrical insulation to prevent accidental contact between conductive components.
When a plastic battery holder is used, the strip pitch normally needs to correspond to the holder's cell center spacing.
For 18650 packs, 19.0 mm can be used in certain standard holder configurations.
For 21700 packs, 22.5 mm can be used in certain standard holder configurations.
The actual holder specification should always be checked before ordering a large quantity of punched nickel strip.
Different holders may have different:
Cell spacing
Slot dimensions
Wall thickness
Cell retention structures
Terminal clearance
Plastic tolerances
Insulation requirements
A nickel strip manufacturer can produce custom punched patterns when the customer provides the required pitch and geometry.
Punched nickel strip is a pre-processed strip containing holes, tabs, slots, or other geometric features.
Instead of manually positioning individual pieces, the punched strip can be aligned with multiple cells.
Advantages may include:
Faster assembly
More consistent positioning
Reduced manual cutting
Repeatable connection geometry
Easier automated feeding
Better alignment with cell holders
Customized series and parallel layouts
Reduced assembly labor
Punched strips are particularly useful for repeated battery pack designs.
The punching pattern can be designed according to the number of cells, cell arrangement, connection direction, and required terminal positions.
Stamped nickel tabs are formed from strip material using stamping or punching equipment.
The resulting tab can have a customized geometry, including:
Straight tabs
Offset tabs
L-shaped tabs
U-shaped tabs
H-shaped connections
Multi-cell bridge tabs
Series connection tabs
Parallel connection tabs
Custom terminal tabs
Stamped tabs are useful when a simple rectangular strip cannot satisfy the mechanical or electrical layout of the battery pack.
Nickel strip thickness is one of the most important product specifications.
Common battery strip thicknesses include:
0.05 mm
0.08 mm
0.10 mm
0.12 mm
0.15 mm
0.20 mm
0.30 mm
Thinner strip can be useful for compact connections and lower-current applications.
Thicker strip may provide greater mechanical strength and a larger conductive cross-sectional area, but thickness alone does not determine the maximum safe battery current.
The required current capability depends on the entire electrical path.
Important factors include:
Material resistivity
Strip thickness
Strip width
Strip length
Number of parallel strips
Weld resistance
Contact resistance
Battery configuration
Continuous current
Peak current
Ambient temperature
Cooling conditions
For high-current applications, engineers should calculate or measure the actual resistance and temperature rise of the complete interconnection system.
Common strip widths may include:
2 mm
3 mm
4 mm
5 mm
6 mm
8 mm
10 mm
12 mm
15 mm
20 mm
Custom widths can be produced through precision slitting.
A wider strip provides a larger cross-sectional area when thickness remains constant. However, a wider strip can also influence the weld area, bending behavior, battery spacing, insulation design, and package dimensions.
For punched strips, width must be coordinated with the hole pattern and cell terminal geometry.
Nickel strip may be supplied as continuous coil material or cut to specific lengths.
Continuous material is useful for automated production.
Cut strip is useful for manual assembly or smaller production batches.
Custom length can reduce material waste when the strip is designed for a particular battery pack.
The required length depends on:
Number of cells
Cell spacing
Connection direction
Tab overlap
Welding location
Terminal geometry
Insulation clearance
Battery enclosure
A precise drawing is recommended for complex punched or stamped components.
A series battery connection connects the positive terminal of one cell to the negative terminal of another cell.
The nickel strip acts as an electrical bridge between the cells.
For multi-cell battery packs, the strip may contain multiple connection points.
The physical layout must correspond to the electrical circuit.
For example, a pack may contain multiple parallel cells followed by a series connection to another parallel group.
The nickel strip pattern must therefore be designed according to the complete electrical topology rather than only the physical cell arrangement.
Parallel connections connect cells with the same polarity.
Parallel battery configurations can increase available capacity and current capability depending on the cell design and electrical configuration.
The connection strip must provide an appropriate current path between the cells.
For larger current requirements, engineers may use:
Wider strip
Thicker strip
Multiple parallel strips
Multiple weld points
Busbar structures
Hybrid interconnection systems
The strip design should be validated under the intended continuous and peak operating conditions.
Resistance spot welding is one of the most common methods for attaching nickel strip to cylindrical battery cells.
The process generally involves placing the strip on the cell terminal and applying welding electrodes.
A controlled electrical pulse generates localized heating at the interface.
The welding process typically includes:
Cell positioning
Strip positioning
Electrode placement
Welding pulse
Weld formation
Visual inspection
Mechanical or electrical verification
Insulation and pack assembly
The exact welding parameters depend on the strip material, thickness, surface condition, electrode geometry, welding machine, and cell terminal construction.
There is no universal spot welding setting that applies to every nickel strip.
Weld quality is critical because the strip may carry substantial current during battery operation.
A weak weld can increase electrical resistance and generate localized heat.
A properly developed welding process should consider:
Weld current
Pulse duration
Number of pulses
Electrode pressure
Electrode tip geometry
Strip thickness
Material type
Nickel coating
Cell terminal material
Surface cleanliness
Welding machine characteristics
Production battery assembly should establish appropriate inspection and process controls.
Resistance welding qualification practices can include visual inspection, destructive testing, peel testing, metallographic evaluation, and process verification depending on the application.
Battery cells are sensitive to excessive heat.
Although spot welding is designed to concentrate heat locally, poor welding parameters can create unnecessary thermal exposure.
The objective is to form a reliable weld while limiting heat transfer into the cell.
Important factors include:
Welding energy
Pulse duration
Electrode pressure
Weld location
Strip thickness
Cell terminal structure
Number of welds
Cooling time
For production applications, welding parameters should be established experimentally using the actual cell, strip, and welding machine combination.
Surface condition affects welding consistency.
Potential surface variables include:
Nickel coating quality
Oxidation
Oil contamination
Dirt
Surface roughness
Plating thickness
Storage conditions
Clean and consistent material generally helps achieve more repeatable welding.
Nickel plated steel should also be evaluated for coating adhesion and consistency when the material will undergo cutting, punching, stamping, or forming.
When nickel plated steel is produced from a large plated coil and subsequently slit, the top and bottom surfaces can retain the nickel coating while the newly created side edges may expose the steel substrate.
This is an important characteristic of slit nickel plated steel strip.
Therefore, the side edge of a finished slit strip should not automatically be assumed to have a continuous nickel coating.
For applications where edge coverage is critical, the material construction and manufacturing process should be specified separately.
Nickel plated stainless steel is different from nickel plated low carbon steel.
Stainless steel has different electrical and mechanical properties from low carbon steel.
For battery connection applications, the substrate selection can significantly influence resistance.
A nickel plated stainless steel strip should therefore not be treated as a direct substitute for nickel plated SPCC steel strip.
The statement that stainless steel strip may have approximately three times the resistance of a comparable nickel plated steel strip is application-dependent and should be verified by actual material dimensions and electrical measurements.
The important principle is that the substrate material influences the electrical performance of the finished strip.
Electrical resistance can be understood through the relationship between material resistivity, length, and cross-sectional area.
For a uniform conductor:
R = ρL/A
where:
R is electrical resistance
ρ is material resistivity
L is conductor length
A is cross-sectional area
For a rectangular strip:
A = width × thickness
This means increasing strip width or thickness generally reduces the resistance of a given strip length, assuming the same material.
However, the total battery connection resistance also includes:
Strip resistance
Weld resistance
Contact resistance
Cell terminal resistance
Connection geometry
Other conductive components
Therefore, selecting nickel strip based solely on thickness is insufficient for high-current applications.
There is no single universal current rating for a particular nickel strip thickness.
For example, a 0.15 mm strip may behave differently depending on whether its width is 3 mm, 6 mm, or 10 mm.
The material also matters.
Pure nickel and nickel plated steel do not have identical electrical properties.
Battery pack designers should consider:
Continuous current
Peak current
Pulse current
Ambient temperature
Allowed temperature rise
Strip geometry
Connection length
Parallel current paths
Weld resistance
For critical battery systems, thermal and electrical validation should be performed using the final assembly.
High-current battery packs require careful interconnection design.
Potential approaches include:
Wider nickel strip
Thicker nickel strip
Multiple parallel strips
Multiple weld points
Nickel busbars
Copper conductors with nickel interfaces
Hybrid current collectors
Pure nickel is frequently considered when the strip itself must provide a low-resistance conductive path.
However, a nickel strip should not be selected based solely on the phrase “high current.”
The complete electrical path must be evaluated.
Energy storage systems may contain large numbers of cylindrical cells.
Nickel strip can be used for cell-to-cell interconnections in compact battery modules.
Typical requirements include:
Repeatable cell spacing
Consistent welding
Stable electrical resistance
Mechanical durability
Insulation compatibility
Controlled manufacturing tolerances
For larger energy storage systems, the connection design may combine nickel strip with busbars, fuses, current collectors, BMS connections, and other electrical components.
Power tools can require relatively high current during motor startup and operation.
Battery pack interconnections therefore need to withstand both continuous and transient electrical loads.
Nickel strip can be used in cylindrical cell configurations where spot welding is appropriate.
The strip design should consider the number of cells in parallel, expected current, cell chemistry, cell specifications, and thermal requirements.
Electric bicycles, scooters, light electric vehicles, and other mobility products may use cylindrical battery cells.
The battery pack can contain many cells connected through series and parallel arrangements.
In these applications, nickel strip selection should consider:
High current
Vibration
Mechanical movement
Thermal cycling
Long service life
Insulation
Weld reliability
For demanding applications, the battery interconnection should be validated under representative vibration, current, and temperature conditions.
DIY battery pack construction commonly uses 18650 and 21700 cylindrical cells.
Nickel strip is often selected because it is compatible with battery spot welding equipment and can be purchased in small or bulk quantities.
For DIY applications, it is particularly important to avoid treating soldering as a replacement for proper cell interconnection procedures.
Direct soldering onto cylindrical lithium cell terminals can expose the cell to excessive heat.
A controlled spot welding process is generally more suitable for attaching thin battery strip to cell terminals.
Pre-cut nickel strips are supplied at predetermined lengths.
They are useful for:
Small production
Repair work
Prototype battery packs
Manual assembly
Standard battery layouts
Pre-cut strips can reduce the need for manual cutting and improve dimensional consistency.
Coil strip is suitable for high-volume manufacturing.
A continuous roll can be fed into:
Slitting machines
Punching machines
Stamping presses
Automatic battery assembly equipment
Cutting systems
Forming machines
Coil processing can improve production efficiency when the same strip geometry is used repeatedly.
Custom punching allows manufacturers to create specific patterns for individual battery pack designs.
A drawing may define:
Overall strip length
Strip width
Material thickness
Hole diameter
Hole spacing
Pitch
Tab length
Tab width
Bend position
Terminal position
Series connection pattern
Parallel connection pattern
This type of customization is especially useful when standard straight strips cannot match the cell arrangement.
The hole pattern in a punched strip can serve several functions.
It may:
Align with cell terminals
Reduce material weight
Create defined welding areas
Provide mechanical clearance
Match a battery holder
Create a flexible connection
Form a custom electrical path
The hole geometry should not interfere with welding electrode access.
The distance between holes must also correspond to the actual cell center distance.
Center distance is especially important for multi-cell punched strips.
For cylindrical cells, the pitch is determined by the center-to-center distance between adjacent cells.
A theoretical cell diameter does not necessarily equal the final pitch.
For example, a nominal 18 mm diameter 18650 cell may be placed at a pitch greater than 18 mm because of:
Cell wrapping
Holder walls
Insulation paper
Mechanical clearance
Manufacturing tolerance
Battery pack structure
Similarly, a nominal 21 mm 21700 cell may use a pitch greater than 21 mm.
Research and engineering references emphasize that nominal cylindrical cell dimensions can vary between actual commercial cells.
An 18.5 mm pitch can be used for certain 18650 rackless battery arrangements where cells are positioned closely together.
This configuration minimizes the distance between adjacent cell centers.
It is suitable only when the actual cell dimensions and insulation requirements allow the close arrangement.
Before production, the strip should be tested against the actual cells.
A 19.0 mm pitch is commonly associated with certain 18650 plastic battery holder arrangements.
This pitch can provide additional spacing compared with a close rackless layout.
It is useful when a battery holder defines the cell center positions.
The actual holder specification should be checked because plastic holders are available in different designs and dimensions.
A 19.5 mm pitch provides additional spacing for certain 18650 configurations.
It may be suitable where a thicker support structure or insulation paper gap exists between cells.
The appropriate pitch should be determined from the complete mechanical design.
A 21.5 mm pitch can be used for certain 21700 rackless battery arrangements.
Because a nominal 21700 cell has an approximate diameter of 21 mm, the 21.5 mm pitch provides a relatively small clearance.
Actual cell diameter should be verified before selecting this configuration.
A 21.8 mm pitch can be used in certain 21700 bare-cell arrangements with a small clearance.
The difference between 21.5 mm and 21.8 mm may appear small, but it can influence the final battery pack geometry.
This is especially important when many cells are positioned in a repeated pattern.
A 22.5 mm pitch can be used for certain 21700 plastic battery holder configurations.
The additional spacing allows for the holder structure and mechanical clearance around the cells.
The actual holder should be measured or specified before producing custom punched nickel strip.
A typical nickel strip manufacturing process may involve several stages.
The raw material is selected according to the required grade, thickness, width, and surface condition.
For nickel plated steel, the substrate and nickel coating are controlled as part of the material specification.
Large coils can be slit into narrower strips.
Precision slitting controls the final width.
The continuous strip can be cut into predetermined lengths.
A punching process can create holes and connection patterns.
Stamping can produce more complex tab shapes.
Certain designs may require bending or shaping.
Finished strips can be inspected for dimensions, surface quality, burrs, coating condition, and other characteristics.
Punching and slitting can create small burrs along the edges.
Excessive burrs can create several problems:
Insulation damage
Short circuit risk
Poor fit
Inconsistent handling
Reduced assembly quality
For battery applications, burr control is therefore important.
A custom punched strip specification may include requirements for:
Maximum burr height
Edge condition
Hole quality
Cut surface
Dimensional tolerance
Dimensional tolerance is particularly important for custom battery strips.
Relevant dimensions can include:
Thickness
Width
Length
Pitch
Hole diameter
Hole position
Tab width
Tab length
Overall pattern length
A small pitch error can become significant across a long multi-cell strip.
Therefore, dimensional inspection should be performed using appropriate measuring equipment.
The surface should be free from obvious contamination, excessive oxidation, severe scratches, and defects that could interfere with welding or assembly.
For nickel plated steel, surface quality also includes:
Coating continuity
Plating adhesion
Surface appearance
Coating thickness
Resistance to handling damage
The required inspection level depends on the application.
Nickel strip should be stored in conditions that protect it from contamination and excessive moisture.
Recommended storage practices can include:
Dry storage
Clean packaging
Protection from chemicals
Protection from excessive humidity
Avoiding unnecessary surface contact
Keeping rolls properly packaged
Preventing mechanical deformation
Long-term storage conditions should follow the material supplier's specifications.
Nickel strip may be packaged as:
Coil rolls
Individual cut strips
Bundled strips
Punched strips
Stamped tabs
Custom sets
Packaging should protect the material from:
Bending
Scratching
Contamination
Moisture
Edge damage
For precision punched components, packaging should also prevent the pieces from becoming tangled or deformed.
A battery strip quality control program can include several inspection stages.
Verify:
Material type
Grade
Thickness
Surface condition
Plating condition
Check:
Width
Thickness
Length
Pitch
Hole position
Hole diameter
Look for:
Scratches
Oxidation
Burrs
Surface contamination
Plating defects
Use representative samples to confirm:
Weld formation
Weld strength
Electrical continuity
Process stability
For industrial battery applications, the inspection plan should be established according to the end product requirements.
Mechanical weld testing helps determine whether the connection is strong enough for the intended application.
Possible testing methods include:
Peel testing
Pull testing
Destructive weld testing
Visual inspection
Cross-sectional examination
Electrical resistance testing
A good weld should provide a stable electrical and mechanical connection.
Testing should use representative samples produced under actual manufacturing conditions.
Electrical testing can help identify excessive resistance.
Testing methods may include:
Four-wire resistance measurement
Milliohm measurement
Voltage drop testing
Current load testing
Temperature rise testing
For a battery pack, the resistance of the complete connection path is more meaningful than the resistance of the raw strip alone.
Thermal testing evaluates how the interconnection behaves under load.
A test may measure:
Strip temperature
Weld temperature
Cell temperature
Connection temperature
Ambient temperature
The test should represent the actual current profile.
A strip that remains cool under one current level may become significantly warmer at a higher continuous current.
Battery pack interconnections are part of the overall electrical safety system.
Poor strip selection or poor welding can create high-resistance connections.
High resistance can generate heat according to:
P = I²R
where:
P is heat generated
I is current
R is resistance
This relationship shows why even a relatively small increase in resistance can become important at high current.
For example, if current increases significantly, heat generation rises according to the square of current.
Therefore, battery pack designers should validate connection resistance and temperature under the actual operating conditions.
Nickel strip is conductive, so insulation must be considered throughout the battery pack.
Common battery insulation components include:
Insulation paper
Fish paper
Polyimide tape
Electrical tape
Plastic cell holders
Insulating sheets
Terminal insulating rings
The insulation system should prevent unintended contact between conductive components.
Sharp edges and burrs on punched or cut strip should be controlled to reduce the possibility of insulation damage.
Cell holders can provide:
Cell spacing
Mechanical positioning
Insulation
Structural support
Assembly alignment
The strip pitch should correspond to the holder's actual center distance.
A mismatch between strip pitch and holder pitch can result in:
Misaligned weld locations
Strip bending
Mechanical stress
Poor contact
Difficult assembly
Therefore, holder and strip should be designed as a matched system.
Automated battery assembly can use continuous strip or pre-punched components.
Automation benefits from consistent:
Strip width
Strip thickness
Pitch
Hole location
Cut length
Surface quality
Feeding characteristics
Custom coil or punched-strip designs can be integrated into automated production equipment when the strip geometry is compatible with the feeding system.
Manual assembly may use pre-cut strips or standard rolls.
Pre-cut components can simplify positioning.
For prototype production, however, custom punched strips may not always be necessary.
A straight strip may be sufficient when:
The battery layout is simple
Cell spacing is standard
Manual positioning is acceptable
Production volume is low
As production volume increases, customized punched or stamped components may provide greater efficiency.
Prototype battery packs often require flexibility.
During development, engineers may test:
Different cell arrangements
Different strip widths
Different thicknesses
Different pitch values
Different weld configurations
Different insulation structures
Small quantities of cut strip can be useful during early development.
After the design is finalized, custom punched or stamped strips can be introduced for production.
When ordering custom battery welding strip, the following information is useful:
Material
Specify pure nickel, nickel grade, or nickel plated steel.
Thickness
Specify the required thickness in millimeters.
Width
Specify the strip width.
Length
Specify the individual piece length or coil requirements.
Pitch
Specify the center distance for repeated connection points.
Hole Pattern
Provide hole diameter, position, and quantity if punching is required.
Tab Geometry
Provide the required shape and dimensions.
Battery Format
Specify 18650, 21700, 26650, 26700, 32650, or another cylindrical cell format.
Battery Arrangement
Specify series, parallel, or series-parallel configuration.
Welding Method
Provide information about the resistance welding process if available.
Production Quantity
Specify prototype, small batch, or mass production requirements.
Typical battery welding strip sizes may include:
0.10 mm × 2 mm
A narrow strip for compact and lower-current connection applications.
0.10 mm × 5 mm
A commonly used thin strip format for general cylindrical cell connections.
0.15 mm × 5 mm
A useful combination for many standard battery pack designs.
0.15 mm × 8 mm
Provides a larger conductive cross-sectional area.
0.20 mm × 8 mm
Suitable for applications requiring additional mechanical strength and conductive area.
0.30 mm × 10 mm
A thicker and wider format for demanding connection designs when compatible with the welding process.
These are examples rather than universal current ratings.
A practical selection process can follow several steps.
Determine whether the pack uses:
18650
21700
26650
26700
32650
Other cylindrical cells
Do not rely only on nominal cell format.
Actual dimensions can differ between cell designs.
Measure the center-to-center distance required by the battery holder or rackless layout.
Calculate the expected continuous and peak current.
Choose between pure nickel and nickel plated steel according to electrical, mechanical, welding, and cost requirements.
Select a suitable cross-sectional area and geometry.
Choose coil, cut strip, punched strip, or stamped tab.
Test the selected material using the actual welding equipment.
Measure the connection temperature under representative current.
Ensure that the strip dimensions match the actual battery assembly.
Thickness alone does not determine electrical performance.
Width and material must also be considered.
Nickel plated steel is not the same as solid nickel.
The material should be clearly specified.
A punched strip with the wrong pitch may not fit the cell layout.
Nominal cell dimensions are not always identical to actual dimensions.
Different materials and thicknesses require different welding conditions.
Sharp punched edges can damage insulation.
The final battery connection includes the weld and contact interfaces.
A connection can appear electrically functional while still producing excessive heat under high load.
The 18650 and 21700 formats are particularly relevant to cylindrical battery pack design.
The 18650 is approximately 18 mm in diameter and 65 mm long, while the 21700 is approximately 21 mm in diameter and 70 mm long. Commercial cell dimensions can vary, so mechanical design should be based on the actual cell specification.
For these formats, nickel strip can be supplied as:
Straight strip
Continuous roll
Pre-cut strip
Punched strip
Stamped tab
Custom connector
Multi-cell interconnect
The correct pitch depends on the cell arrangement and holder.
Nickel strip is a small component, but it can have a major influence on battery pack performance.
A properly selected strip should provide:
Appropriate electrical conductivity
Suitable mechanical strength
Reliable weldability
Adequate corrosion resistance
Correct dimensions
Proper cell alignment
Appropriate current capacity
Stable production quality
For 18650 and 21700 battery packs, pitch is particularly important when using punched nickel strip.
The commonly referenced configurations include 18.5 mm, 19.0 mm, and 19.5 mm for certain 18650 arrangements, and 21.5 mm, 21.8 mm, and 22.5 mm for certain 21700 arrangements.
These dimensions should always be checked against the actual cell, cell holder, insulation, and battery pack design.
Before purchasing or manufacturing a nickel strip for battery welding, verify the following:
Material type
Nickel grade
Steel substrate if applicable
Nickel coating if applicable
Thickness
Width
Length
Pitch
Hole diameter
Hole position
Tab geometry
Burr requirements
Surface condition
Weldability
Electrical resistance
Packaging
Quantity
Application
Battery cell format
Cell arrangement
Welding process
A complete specification reduces the risk of receiving a strip that is physically similar but unsuitable for the intended battery pack.
Nickel strip is used as an electrical interconnection between battery cells. It can connect cells in series or parallel and is commonly attached using resistance spot welding.
No. Pure nickel strip consists primarily of nickel throughout its thickness. Nickel plated steel consists of a steel substrate with a nickel coating.
Yes. Nickel and nickel plated steel strips are commonly used in resistance spot welding applications, provided that the welding equipment and parameters are suitable for the selected material.
There is no universal best thickness. The appropriate thickness depends on material, width, current, connection length, weld configuration, thermal requirements, and battery design.
Both pure nickel and nickel plated steel are used for 18650 battery connections. The selection depends on current requirements, welding performance, mechanical requirements, and cost.
Both pure nickel and nickel plated steel can be used for 21700 battery packs. The required thickness, width, and pitch depend on the specific battery design.
Nickel strip pitch normally refers to the center-to-center distance between repeated cell connection positions.
A 19.0 mm pitch can be suitable for certain 18650 battery holder configurations. The actual holder and cell dimensions should be verified.
A 22.5 mm pitch can be suitable for certain 21700 plastic battery holder configurations. The actual holder specification should be confirmed.
Different battery packs use different holders, insulation structures, cell clearances, and mechanical arrangements.
Yes. Nickel strip can be punched according to specified pitch, hole pattern, tab geometry, length, and width.
Yes. Continuous coil rolls are commonly used for slitting, cutting, punching, stamping, and automated battery assembly.
Yes. Nickel strip can be supplied as individual cut pieces according to the required length.
Not necessarily. When a nickel plated coil is slit, the newly created side edges may expose the steel substrate.
No. Stainless steel and low carbon steel have different electrical and mechanical properties. The substrate should be clearly specified.
Depending on the application, weld quality can be checked through visual inspection, electrical testing, peel testing, pull testing, or other qualification methods.
Pitch determines whether the punched strip aligns correctly with the cells and holder. Incorrect pitch can cause mechanical and welding alignment problems.
Nickel strip for battery welding applications is an important interconnection material for cylindrical battery packs. It combines the functions of electrical conduction, mechanical connection, and resistance welding compatibility.
The two major material categories are pure nickel strip and nickel plated steel strip. Pure nickel can provide strong electrical and corrosion-resistance characteristics, while nickel plated steel can offer a practical combination of mechanical strength, weldability, and cost.
For 18650 and 21700 battery packs, the selection process should consider much more than strip thickness. Cell format, actual cell dimensions, pitch, holder structure, strip width, thickness, material, weld parameters, current, thermal behavior, and insulation all contribute to the final battery connection design.
Punched nickel strip can further improve assembly efficiency by integrating multiple connection positions into one component. Center distance is especially important because a small pitch difference can affect the alignment of an entire multi-cell battery pack.
The reference pitches of 18.5 mm, 19.0 mm, and 19.5 mm for certain 18650 arrangements and 21.5 mm, 21.8 mm, and 22.5 mm for certain 21700 arrangements can be used as starting points for product development. However, these values should be confirmed against the actual cell and holder dimensions rather than treated as universal standards.
For reliable battery pack production, nickel strip should ultimately be evaluated as part of the complete electrical and mechanical system. Material selection, strip geometry, welding parameters, dimensional tolerance, insulation, and thermal performance should be validated together.
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