Some further questions if I may...hope their not too simple or repetitive ?
Is there an 'official' definition of Grade A cells vrs Grade B ?
And what qualifies as "Matched" .
similar "balanced" (I presume at same Voltage and SOC, and thus capacity ?)
And re discussion of an initial 'long' charge at 3.65V / =TOP Balance to 3.65V ? .. but its recommended to not do that again ? Are new Cells presumed not to have been charged to that ? used cells one would assume have ?
If its rated for 280ah and it doesn't get 280ah during a capacity test, then they are not grade A, otherwise they are not 280ah batteries.
Maybe this info below can be added to the OP to save everyone time unless you want everyone to read almost 400 posts for 2+ hours - which people won't. So you will die a frail old man at you computer answering the same questions over and over, from noobs like me, for ever and ever, until the end of time, until you are old and grey like the guy in UP.
Well that got a little dark. I should sleep instead of posting this at 4am, but alas I cannot sleep.
After waking up at 1am, eventually I started to read. I spent 2+ hours reading this thread. I skimmed some very long arguments about types of dielectric grease vs silver etc to prevent corrosion d/t dissimilar metals, but I read most of it. Read about galvanic corrosion in the marine environment if you are curious. Anyway, here is the summary, not my opinions, but rather a summary. I will add links later for my future reference. Pardon my phone voice to text typing/ grammar.
In the end, three people out of the 396 posts did capacity tests, and all 3 said they past. Average was in the 270s for a 280ah. I'm not sure that qualifies as grade A. Some people believe that the ah will increase over time (a few cycles) and depends on slow vs fast discharge. Will Prowse addresses this in his videos, and how if it says its rated for that amount, it better be that amount or more. For example Eve vs Lishen (with the square plastic surrounding the terminal)- advertises 272ah in their specs vs 280ah thst Eve advertises. So either these EVE cells are B or they are not 280ah. But overall you are not getting crap or 100ah cells
They all shipped well in good packaging
You want DDP pricing which includes tarrifs/taxes etc.
Fedex gets the packages off the boats and delivers to your door. Plan for a month or 2 depending on the port.
For $1400+ In the end 16 cells with better than 80% of the 280ah, and is around a 14kwh pack. So it costs about the same as a 5kwh bigbattery.com 48v battery. But you need a BMS and a wooden case to compress the batteries to prevent internal delamination in order to decrease degredation or bulging. So, it's 1/3rd the cost of a solid brand, but requires work.
You want grub screw posts that you can insert then the nut provides the clamping force not the twist of a normal screw/bolt. This way you also can't screw through the bottom on the posts. Use red lock tight for permanent blue for removable. They connection is made between the lug and top surface of the terminal. They are M6 1.0 thread, Minimum length is 20mm long, but 30mm will allow for a second nut to lock the 1st nut down and there is no reason not to have a taller post.
The consensus is to make your own bus bars, many people mentioned copper flat stock. I wonder about smashing a copper pipe in a vise to flatten like some lugs as a cheap alternative. Tho it seems like stress cracks could form and create heat/shorting. The included bars are better than some people have seen from other suppliers depends on your needs if you want to upgrade.
Personal recommendation:
FYI - Dielectric grease will decrease the amount of oxygen getting to the surfaces quite a bit thus decreasing corrosion. We always use at least about a teaspoon amount on boat terminals. Wipe some on the surfaces of the lug, posts, and terminals, and then after bolting down, put a glob over the terminals yo cover everything. After half a decade the posts will still be clean even with dead boat batteries and all the acid involved when they bring the boats back in dead. The residential house kind from home depot is cheaper but thinner and oozes off the posts just leaving a thin coat. The permatex brand is thicker and the glob stays where you put it. There is literature and why you don't use the colored auto battery terminal stuff, but I just always remembered use the clear/Permatex after reading it.
All references said these were EVE cells and many pages were about decoding EVE date codes. Also compared to lower ah Lishen cells. Basen also sells Lishen cells if you are interested. Although maybe Lishen lists thier real ah rating at 272 vs 280 to be fair vs EVE and thus they would be grade A if EVE had legit specs. Many believe these are high quality grade B, the best rejects.
Lishen vid -