The holes are too small for me to drill out and add a 0-80 insert. 0-80
threaded rod fits in there and there is room to add heat shrink. My problem is the bottom insulating the positive attaching it to the center pin. There is very little room in there
Simple cover the whole rod with heat shrink minus 1/8" at the end for the 510 connector, and 1/4" for the top connection. Bend a wire so it fits perfect and then bend the rod to match the wire. Use silicone in the 510 connector and press it in wet. So it is electrically and
juice leak proof. For the neg connector, use a 0-80 1/2" screw and nut and push it in from the bottom and install the nut and cut the excess leaving 1/8" of threads. Then use a second nut to lock the wire for the neg post.

Dan
Added:
Example:

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Would be neat if you could tap the connector center post 0-80, so the threaded rod could be screwed in. No soldering

Dan
Added:
The center hole would have to be .047 for tapping, the maxmimal diameter for the threads are .0628
So if a 1/16 drill bit will not fit into the center pin, it could be tapped 0-80

I know there are some small hole center pins and some large hole center pins. Depends on the type you have. Of course you would only want to tap it 3/4 of the way through so you could tighten the center pin on the treaded rod.
Dan