Battery terminal cleaning with scotchbrite

[No Idea]

Hello, i bought scotchbrite 7447 and measured battery IR before and after cleaning by hand but there was no change. I then put the scotchbrite on an orbital sander and gave the terminals a three second buzz while pressing firmly. Still no change.

I am measuring with a YR1035+ so is it just that I am not measuring the change under load or am I missing something on how long /hard to press to clean terminals with scotchbrite? They did change from shiny to matt and my finger had aluminium dust when I wiped the terminal.

My terminals are the flat type with threaded hole so no need for a dowel.

I have no ox ready and have sanded and nickel plated my copper busbars. I will blow the dust and wipe with IPA. This is the last piece of the puzzle before I start assembly.

 

[zolee]

When you use the YR1035+ it's pins peirce through the oxide layer which is incredibly thin.
When you place the flat busbar there is a large flat surface with oxide layer in between with no way to break through. Just a little bit of mechanical work is enough to remove the oxide, then when you place the busbar and tighten it down it will form a nice contact.

 

[Ampster]

I only clean the terminal tops I can assemble immediately and apply No Alox right after cleaning. The oxide forms very quickly. I also like Scotch Bright pads because they do not contain any metal.

 

[zolee]

Yes, the oxide forms at the moment fresh aluminium is exposed to oxygen, that's moments after you clean it. But it takes time to form a thicker layer.

Aluminium oxide is also incredibly hard - almost diamond hard. You can try measuring first without cleaning, but with busbar mounted, then clean and measure again. This way you'll measure the contact resistance difference. It's easier than measuring the oxide.

 

[No Idea]

I only did the one cell so thanks for the explanations and suggestions. Sounds like I am doing the sanding right. I will need to tighten down the busbar bolts to get a good comparison reading so instead I will just go for it (and resand the cell I did yesterday) and assume the sanding process is working.

I plan to do a 0.5C capacity test once the packs are made up and I have an IR thermometer gun to check for hot connections.

Getting close to finishing my first build. Exciting stuff.

 

[JoeHam]

I also like Scotch Bright pads because they do not contain any metal.

Actually many DO contain metal.

I specifically use the red ones on aluminum since the red ones contain aluminum. I’ve always used them on aluminum antenna parts and aluminum terminals.

Others contain titanium and other substances.

 

[HRTKD]

Yeah, what Joe said. Many of the Scotch-Brite pads have Aluminum Oxide for an abrasive. Be sure you clean the cell terminal surface after sanding. I use Acetone or Mineral Spirits, whichever is closer at hand.