Cleaning battery contacts

[sylvandb]

(06-20-2014 06:24 PM)anetzer Wrote:  

(06-20-2014 05:48 PM)jebem Wrote:  Solder having Pb will oxidize and create a high contact resistance

Looks might be an argument, but to be honest: In a battery compartment I will value good conductivity higher.

Yeah, an argument... Pb oxide is not a concern.

Aluminum oxide on your foil is a very good insulator and forms quickly when aluminum is exposed to air at room temperature. Aluminum oxide is also very hard to penetrate, yet your foil conducted, did it not?

Pb oxide is going to form very slowly at room temperature (if ever) and further it is an unexpectedly reasonable conductor. If it were not, your car battery would not deliver the huge starting current necessary.

The lead itself is a poor conductor compared to other metals (and yet it works for battery terminals carrying hundreds of amps). Of course, your leaded solder is likely only 30% to 40% lead and nearly all of the rest is typically tin. It will be fine. And it is easier to work with and workable at lower temperatures.

Silver is the best conductor, but lead-free plumbing solder has only small percentage of silver along with a whole stew of others. Silver oxide is also an insulator.

Or maybe you could solder it up nice and neat (it can be even, just takes practice and proper flux) and then burnish gold leaf into the surface to prevent corrosion.

Really, the biggest problem with soldering contacts is not causing heat damage. The solder will oxidize less and cause fewer problems than the spring steel exposed from under the nickel plating. Even so, if the contacts are in the calculator I would leave them as bare spring steel rather than solder them. Too much heat!