Battery Contact Considerations
• Dimensional: ANSI and IEC industry standard dimensions should be used when designing a battery compartment to avoid battery fit problems.
• Mechanical Properties: The material must have enough ductility, should be strong to avoid deformation, should not relax over time, and should resist wear.
• Electrical Conductivity: The better the conductivity of the connector the lower the contact resistance will be.
• Environmental Stability: It is particular important that the contact material does not corrode, or cause corrosion of the materials that it is in contact with.
• Cost: No material is perfect. There are often trade-offs between the aforementioned material considerations.
Practical solutions often involve coating a substrate to get an optimum combination of properties. That is, the coating primarily provides the electrical and environmental properties; whereas, the substrate gives most of the mechanical properties, with a possible cost reduction if a relatively cheap material is used.
Plating and Substrates
1. Gold Plating - Provides the most reliable metal-to-metal contact under all environmental conditions.
2. Nickel (Solid) - Provides excellent resistance to environmental corrosion and is second only to gold plating as a contact material. Solid nickel can be easily drawn or formed.
3.Nickel Clad Stainless - Performs almost as well as solid nickel with excellent resistance to corrosion.
4. Nickel-Plated Stainless - A widely used material. Non-plated stainless steel is not recommended due to the adverse impact of passive films, which develop on the surface and result in poor electrical contact.
5. Inconnel Alloy - Provides good electrical conductivity and good corrosion resistance. However, soldering may be difficult unless an active flux is used.
6. Nickel-Plated Cold-Rolled Steel - An economical contact material that provides a good contact surface for welding and soldering.
• The connectors used with conventional cylindrical cells are primarily Ni-plated
• The Ni-plating must be adherent, continuous, non-porous, and resistant to wear. The suggested plating thickness is 200 micro-inches.
• Avoid Sn-plating for connectors due to possible galvanic corrosion and fretting wear/corrosion.