PC1100 Battery Post Repair

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. 

The only problem is the tap was for a through hole. It isn't a bottoming tap.  So I ground off the end of the tip to make it closer to a bottoming tap.   I tried drilling a piece of lead to see how deep I needed to drill and how well it worked.   It looks like I could get away with 1/2 inch.   The M6 set requires a ,250 hole to tap.  

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.

2019 Team USA F3b Fund Raiser

Please visit the Team USA fund raising sight and help the team make the trip to the world championships.
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2019 Team USA Logo Complete

The 2019 Team Logo has been completed.  Really nice design.