Need finish recommendation for stainless steel battery contact
A discussion started in 2003 but continuing through 2017(2003)
Q. I have a 301 stainless steel leaf spring battery contact in contact with a stainless battery case that seems to occasionally suffer from high contact resistance (it's a 3 volt battery at a very low current draw). I'm considering nickel plating the stainless parts to reduce the contact resistance from the passivation on the stainless steel. I'm considering a sulfamate nickel to keep the ductility high. Does this seem a reasonable choice? If not, alternate suggestions would be welcome.
mechanical engineer - Garrett, Indiana, USA
A. Sulphate nickel is okay, electroless nickel is better as a contact surface but not as ductile. If this is truly low low current draw though, recognize that some contacts are gold or other precious metals not because people want to spend the money but because all metals except precious metals tarnish, and tarnish is an insulator.
It seems that battery terminals, earphone plugs, charging contacts and the like can be nickel, but digital signals usually require gold.
Ted Mooney, P.E.
Pine Beach, New Jersey
A. I wonder if the high resistance is due to oxidation of the stainless steel surface. If it is, I would suggest using an inert metal such as gold, but that could be expensive. It is, however, soft and non-corroding, so it will give you years of excellent service. On the other hand, you could perhaps use copper, as this can also be quite soft and if you have to make-and-break the contact, it is self cleaning by the abrasion it will undergo. You could also use nickel, but this is harder and will also build up an oxide film. Using a bright nickel will reduce this problem, but not eliminate it. In any case, you will have problems getting good adhesion onto the stainless steel, so whatever metal you use, I would suggest you use a cyanide based deposit and/or strike. If you use nickel, you should be able to get away with a Woods nickel strike.
R&D practical scientist
Chesham, Bucks, UK
October 24, 2017 -- this entry appended to this thread by editor in lieu of spawning a duplicative thread
Q. My company makes a battery contact spring from bare 17-7ph stainless. We want to nickel plate it for a follow-on process improvement. Is nickel plating suitable for retaining electrical conductivity in a battery contact application. In other words, will the nickel plating introduce unanticipated resistivity (or possibly other negative effects)? (Assume electrodeposited nickel per AMS QQ-N-290).
Also, which Class is best for this application, Class 1 or Class 2? And why?
Thank you for sharing your expertise.
Quality Engineer - Wilsonville, Oregon USA
December 14, 2017
A. Hello Kelly,
You've already read above this thread on the effects of Nickel on SS so you have your answer.
I would recommend using white bronze plating over the SS.
It resists atmospheric tarnishing, is as hard as nickel and also sometimes replaces silver in low voltage contacts.
All the best,
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