so what is the biggest difference between these cell and the
VariCore 3.2V cells.. the price for 4 -310 Ah vari core is 460.. for the shenzhen luyuan lifepo4 280 ah it like $672.. that a $200 dollar difference.. are they worth that big a difference..?? if so how, why..
You can't compare regular bulk cells (varicore) with matched/binned cells from Luyuan.
Regular cells: Work great, but will drift on low SOC if you topbalance them. Capacity of 310Ah is usually in the range of 290-315Ah, but no guarantee. Total capacity of a pack is determined by the weakest cell.
Matched and binned cells are the top of the range: 280Ah cell is >280Ah guaranteed (mostly more like 290Ah or so) and they are, even at low SOC, almost no cell drift. So also the final pack will be more even, thus getting good results.
Especially when pushing high currents this makes sense.
Also: aftersales, proper English communication and packaging differs between vendors.
If you're willing to get the most of your money and willing to take a bet: Go for the cheapest ones.
But youre taking the risk of slighly lower the quality. Any vendor will say it's grade A and matched, but showing a video with a voltage/resistor testing isn't..
If you're willing to spend a little more, go for Luyuan: you're knowing the quality you're going to get is great and you will get accurate testing reports.
Personally, I'd avoid Ali sellers. These sellers are primary targetting mass volume, not quality. I've seen plenty of people with issues from Aliexpress cells. Varying from shipping damage or scratched QR codes to clearly swollen cells or used cells (which not even get half of their rated capacity)