Thank you for the guidance.
When you purchase 4 cell pack from docan (alibaba) or nkon , are they matched? The seller will pay atention to a 16 pack battery and provide them within the capacity range we want? Or is everything randomly sent to us? If that’s the case, what’s the worst case scenario I’ll be facing?
Thank you
this is just my thoughts and I have no proof other than my own experience.
This is a long read so standby: if you buy from a reseller, or "agent" you have no guarantees other then what they say to you. normally its 98% lies and bullshit.
If you buy form the Company that actually makes the cells then you can believe what they say. the difference in price is immense like almost 4-5 times what the resellers are selling them for.
Over the last two years, all of the sellers including every single one that sells to the members of this forum at one time or another were pawning off second hand and blemish's as if they were brand new EV grade from the factory... first it was no bar code or QR codes, then it was faked stickers, then it was faked QR codes applied to stickers, then it was re-lasered QR codes.
Finally Eve stopped it all by themselves lasering a "B" onto the rejects. once EVE stated doing that actual non reject cells started appearing as they could no longer lie and get away with it. but i personally doubt they are the cream of the crop. I would bet they are outliers that meet the EV standard but probably do not meet the match and batch standards.
Once again this is jut my gut feeling.
I have bought both from vendors, and directly from the factory from a company employee who was communicating to me from a company email address. I also independently verified this by making several discreet email communications behind that person's back to verify with that company to ensure that they were not a scammer.
what was the difference? a five year warranty, packed and shipped in accordance with all applicable laws both Chinese and Japanese and international, batteries that were packed in an actual wooden crate not some combination of cardboard. The final difference was a price that reflected theses differences... some members here on the forum think that I must have been ripped off. No i was ripped off when I paid for supposedly grade "A" EV cells that turned out to be pull offs from a bus or an electrical forklift and resold by unscrupulous vendors. Yes they were cheaper but I got what I paid for... cells that need re-balancing about once a year, that did not meet capacity but have settled down at about 90% of nameplate rating after a year of use.
now the ones I bought direct from the factory, tested in at 120% of their rating, IE the 400 amp hour cells from Winston came in at 455-460 amp hours of capacity that was drawing at .5c and charging at the same (this was for testing, not actual daily use) they have not needed a re-balancing after 6 months and show no evidence of drift form the initial top balance. I am not using active balancers, and the puny balancers in the Dalys BMS's i use would not do anything anyway with a cell this big. they are right now just at the start of the 9th month of use. Other than while testing, the cycle use has been 70~100% daily verified by a bogart engineering trimetric shunt based monitor.
I have two of these packs in 16s (22kWh each, 44kWh total) along with a 3p16s pack (27kWh) of CALB cells i originally bought that together power my house 24-7 with no grid tie.
so if you are building this to power a solar shed, or power a couple of split pack a/c untis or as an emergency backup ,then go with the eve or catl or calb's that the vendors are selling cheap, they will suffice for what you want. if you are building for a house that you want to work daily for the next 20 years buy from the factory and pay the premium.
once again this is all my opinion and your mileage may vary