Quote Originally Posted by mklotz View Post
I don't think the effect is anything to worry about and probably would require the sensitivity of a Wheatstone bridge to detect. Nevertheless, I did an experiment to check.

I have three 50w 1% precision resistors - 10, 1, and 0.1 ohms. I measured all three of them first with no aluminum in the circuit and then with it in. These were the results...

10: 10.2, 10.3
1: 1.2, 1.2
0.1: 0.2, 0.2
I like your execution, very cool. The reason probe ends, terminals, and test point connections are nickel, gold, or rhodium plated is that they don't oxidize. Because aluminum does it will directly affect readings accuracy. Over time oxidation will change them, they could vary month to month. If you are just going for simple go/no-go it's probably fine but if you are doing current measurement or board level troubleshooting to a schematic your test point readings will vary from indicated values. Aluminum forms and oxide layer immediately after it's machined. It's basically an insulator. You can mitigate this (somewhat) by chasing the tapped holes again, quickly adding battery terminal dielectric gel then immediately reinstall the screws. for the banana ends you can fill the voids with the gel. The gel will prevent more air from reaching the machined surfaces. However, some air will reach them as oxidation is immediate after machining.

More here:

https://physics.stackexchange.com/qu...ce-oxide-layer