Rather than poke things into the undamaged charge port of our battery, I built a quick-and-dirty mechanical duplicate:
The “center pin” is a snippet of what’s almost certainly 5/64 inch brass tube measuring Close Enough™ to 2.1 mm, with a few millimeters of 3/32 inch tube soldered on the end to simulate the nugget.
The aluminum rod has a 5.5 mm hole matching the coaxial jack’s diameter and depth, with a smaller through hole for the “pin” and a dab of Loctite bushing adhesive.
Then I turned the end of a 3/8 inch acetal rod down to a 5.5 mm bushing that completely fills the jack:
It has a 3 mm hole down the middle to aim homebrew shell drills directly at the pin, while preventing a short to the side contact.
The first test looked encouraging:
The nugget in the damaged jack is definitely larger than my soldered brass tube, but this was in the nature of exploratory tinkering while mulling the problem.
The Smell of Molten Projects in the Morning 
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2 responses to “Bafang Battery Charge Port: Mechanical Simulator”
[…] Continuing to mull the problem of removing a brass nugget fused to the center pin of the Bafang battery’s charge port without the risk of causing further damage suggested a shell drill fitting over the pin and guided by an insulating bushing: […]
[…] into the rectangular lump at the top of the tool kit, along with the various shell drills and suchlike discussed […]