I have to question the need for an ultra low profile pass-through socket set. Engineers make questionable decisions all the time, but a compound fastener in a low access area isn't something I've ever seen or heard of.
Between the prebuilt batteries I got from Amazon and the ones I built myself, I had 3 different capacities in identical housings. That has been solved with the help of my neighbor's multi-toolhead 3D printer. The nameplates are printed in ABS and are 0.6mm thick.
It's pretty hard to overheat the connections with a normal soldering iron set to 350C. What kind are you using?
The way I do it is to position the tab so it is touching one end of the slot. Once a solder bridge is formed between the two parts, I start dragging the tip of the iron down the...
Mine are working fine. I've also built 4 more batteries; two more with P45B 21700 cells and two with P30B 18650s to use with my leaf blower. I also upgraded the BMS boards on my older set to the new 5 mosfet version. All of them are charging fine on Makita chargers.
I'm not sure what is...
Mine work fine on the new dual-slot chargers, aside from the fact that they're programmed to stop charging at 6Ah, so I have to re-seat them to get a full charge sometimes.
Somebody was confused about how the flange works, but it looks like worst case you'll need a new flange and wax ring. Just grab the T bolts with pliers as recommended earlier.
Any alkaline battery can leak. Eneloops or Energizer lithiums are all I use anymore.
You have to be careful with the Energizer lithiums, though. They have a substantially higher starting voltage and can damage some devices.