280Ah cells with unusual stepped terminals with studs, "normal"??!

[Jesster]

Anyone seen 280Ah EVE cells with terminals like these before? I just received them from Aliexpress seller Tewaycell Battery Store.
The step at the bottom is just over 8mm diameter, my M8 cable ends will not go over it, while of course M10 ends are very loose. The bolt is a standard M6 diameter not that that helps at all. The bus bars are great, but don't fit!!
I've talked to the seller who just contradicts me and tells me this is normal. But I don't see a good contact happening without some fiddling/grinding/drilling.
Haven't tested them yet, just charging them (slowly) now.
Should I dispute this for a partial refund?
Best way to fix this??
For reference I've included one of the listing photos which looks quite different I think.

 

[NVS]

I'm with you. I would want my buss bar to fit over the step. Hopefully, the buss bar is thicker than the step, so you can tighten it down after you drill them out. Drilling them out will make both a good electrical and mechanical connection IMO.

 

[jontm]

Looks to me like M6 internal threads with a stud threaded in. No much wrong with that. M6 seems to be the norm for these EVE LF280 batteries. Not great with regards to the contact area, but in my opinion it is the busbars that are the incorrect type for the battery, not the other way around. I am sure the contact area will be sufficient for <50 A or so. Maybe higher. Probably not a huge deal unless you plan to run high C charge/discharge.
I would not bother complaining about this. To me it seems like the busbars that come with the batteries is mostly some cheap ones they throw in for free.

 

[Browneye]

Discussed at length here with plenty of solutions:

Improving Contact Area on Welded Stud Pads

After the early adopters complained about how easy it was to strip the threads on their prismatic LiFePO4 terminal pads, the market seemed to have responded by offering studs welded onto the original pad, rather than drilling and threading a hole for a bolt. That certainly sounded good to those...

diysolarforum.com

There are at least a couple of sources for aluminum washers to improve contact area, without introducing dissimilar metals.
Worked out quite well:

 

[HRTKD]

I'm probably the outlier here but I would make my own bus bars that fit over that top lip and sit on the base of the terminal. I would use flat bar stock that is thicker than the top lip is tall. For that situation, my material of choice would be aluminum. Copper would work too, but given the contact between dissimilar materials the copper would need to be tinned and I'm not setup to tin copper.

 

[Struc]

I have those same cells. It is how many vendors are selling these EVE cells these days. It's not optimal, but they will work fine for lower amp draws.

The alternatives are available, though, as Browneye mentioned. Give that other thread a read.

 

[Jesster]

Thanks everyone for your input, it's comforting to read through that other thread, and know I'm not the only one scratching my head!!
My initial capacity test on these was reasonable, one cell weaker than the other 3, hitting 2.5V at about 278Ah. Not bad I think for cheap cells (these cost me AU $880 with GST/VAT, vs the BLS which seem to cost closer to $2000).
Given how small the initial step is I think I'll aim to drill out the bus bars and my 8mm lugs to fit over it to the next wider step. Surprising that it doesn't really matter that much!

 

[12VoltInstalls]

I would make my own bus bars that fit over that top lip and sit on the base of the terminal

Exactly what I would do

aluminum washers to improve contact area,

I don’t actually like that much- the contact area isn’t improved, it’s just adding another piece between the contact area and the terminal or busbar.
I’d want spacers at least 0.020 thicker than the shoulder on the stud boss if using terminals or drill aluminum to fit well.

 

[Zwy]

According to this photo and my Superman eyesight, the busbar is thicker than the height of the step. Drill out the busbar to the diameter of the step and it should be fine.

 

[noenegdod]

The pictures are not really good enough to know for certain but if you make a busbar that sits down on the next surface, how flat is that surface? I think I can see weld re-enforcement sticking up in the picture above. You should probably take some time to carefully adjust these spots if you are going to use that surface.

 

[12VoltInstalls]

think I can see weld re-enforcement sticking up in the picture above

Good eye

 

[HRTKD]

The pictures are not really good enough to know for certain but if you make a busbar that sits down on the next surface, how flat is that surface? I think I can see weld re-enforcement sticking up in the picture above. You should probably take some time to carefully adjust these spots if you are going to use that surface.

Yep. That'll screw up a connection for sure.

 

[tommyw3267]

I'm probably the outlier here but I would make my own bus bars that fit over that top lip and sit on the base of the terminal. I would use flat bar stock that is thicker than the top lip is tall. For that situation, my material of choice would be aluminum. Copper would work too, but given the contact between dissimilar materials the copper would need to be tinned and I'm not setup to tin copper.

Correct I like the bar stock concept to make sure bussbars seat correctly, looks like the bat builder was thinking seating multiple bars that actually would fit on the ste.p, then be compressed by the nut,but, all that space is not needed for bars, from cell to cell

 

[dezfutak]

How about drilling out the bus bar sockets so they fit snugly around the uppermost raised ring?

 

[12VoltInstalls]

How about drilling out the bus bar sockets so they fit snugly around the uppermost raised ring?

Surface area. A quick file of the raised beads would give optimal contact. Maybe I’m dumb but that just seems like a poor design.

 

[Browneye]

It's a poor design, but what they facilitated for connecting to flat-top terminals with laser-welding.

The washer fix does increase contact area to either your bus-bars or lugs without introducing dissimilar metals. That's a win. But yeah, it doesn't really increase the contact, just eliminates putting a tinned or plain copper bar or lug on them. Drille out aluminum bus bars might well improve the contact area, and I would still add the aluminum washer on top of that before a nylock nut. Apply oxgard or similar to prevent corrosion with aluminum.

Depending on the application, the as-built is good for 100A or less, without issue. If you're going to run huge current though them then they may not be adequate.

Lots of reading in the other thread - not much more to hash out here.

 

[HRTKD]

Lots of reading in the other thread - not much more to hash out here.

LOL! Ye of little faith. I'm sure we could extend this thread to at least a couple more pages.

Life was a lot easier when all we had was the old-school threaded terminals.