Seems like a fairly large batch of these Lishen Cells got buggered up threads and Luyuan is not the only vendor that got these either as some have reported cells from Basen and a couple of other vendors have the same issue. I only bought EVE cells from the older stock of Bulk/Commodity cells and just received some of the new versions with studs and never encountered such an issue.
IF POSSIBLE try to get cells with laser welded studs which are pretty much impossible to mess up with.
My "Suspicion" is that these Lishen cells came from a Battery Broker. They get cells that are edge case grade cells and B-Grade's but they also get overstock or old stock as well as damaged cells. IMO, These Lishens were likely prepared for a large client and when the screw up was discovered they were dumped to a Broker or two as that would not make any commercial spec at all.
Normally LFP cells will leave a factory with Blank Contacts as different buyers have varying requirements, some may want Laser Welded studs, others would want to Drill & Tap threads for screws/bolts while others would match & batch cells and laser weld busbars and a factory generally won't do such unless it's a "significant" order.
Few options to fix such a defect.
- Redrill the holes straight & Tap in threads, possibly M8. This is a bit tricky but doable with serious patience and care with the right equipment.
- Laser Weld studs over the holes (most likely best option) but cannot be done DIY !
- Install a stud with LocTite or JBW to secure it and then try to "bend" the stud so it sits at 45°.
* Might be easier to put a stud in the hole, mark the tread where it comes to the surface, then extract the stud and put nuts over the area that goes into the cell and then bend the stud while using nuts to protect the thread with just 1-2mm where the bolt will be bent. Would have to mark the line which would go up out of the cell when it is screwed into the hole so that it aligns upright when installed into the cell.
This would certainly require a few practice pieces to make sure the alignment works.
Each cell would have to be done separately because orientations will vary from hole to hole.
Quite a quandary to work out.