My favorite F3b winch battery is an Odyssey Extreeme PC1100. It's only drawback is the weird choice of M6 studs for the battery termination. I have been using some battery posts I machined for a few years, but I did have one of them where the stud broke. I might have over tightened it.
The Swiss team mentioned they had broken one and used a Helicoil to repair the battery. I called up Odyssey and they didn't think there was any way to drill it or enough material there. But looking at it, there clearly is a bit of lead/copper before you get down into the cell. I picked up an M6 helicoil kit.
I mounted the battery in the vice on the milling machine and got out a 1/4 mill I figured a flat bottom would be best to get the depth needed. I was able to go down 9/16 without any problem on the negative terminal that I was repairing.
The helicoil installed nicely. I picked up a M6 bolt on battery terminal and trimmed the bolt to make sure it would be just the right length through the helicoil. Everything looks fine. I have a usable battery now.
Odyssey started making SAE Terminal Kits for the 6mm. This is a relatively new addition. I will be switching to these on the other batteries.