Yes, I think this is what starts happen. Grade A/B are being presented by some re-sellers, like the Globe Power, as ESS or EV grades. It would be perfect if manufacturer was deciding on the purpose a cell can serve - they do the research on products they build and know best what types of failures the mismanufactured items have so they are best to properly group the not meeting EV standards cells. Why they do not do this? It may be that there is such a variation in parameters of mismanufactured cells that is is not worth doing and maybe it is linked to fairly low of failures when compared to scale of production. If there isn't such a variation, it could be a good business as they might create a variation of cells for different purposes, with different specifications. Right now all we have is specification of an A grade cell the manufacturers make but being sold items that do not meet the specifications we got something else - unspecified by manufacturer. I am not referring to EV grade certification but the official specifications manufacturers prepare for their cells. Receiving swollen batteries - they do not meet specified dimensions, often capacity is lower, impedance is higher and number of cycles such cells can survive is known to be lower.
How to tell if EVE cells are A or B, and does it really matter?
- Thread starter apctjb
- Start date
Steve_S
Offgrid Cabineer, N.E. Ontario, Canada
Grade B or Bulk Cells.
You buy 16 cells which all work and are close in IR (Internal Resistance) "generally" @ 3.000, 3.100, 3.200 & 3.400. They test out and there is no more than 5AH capacity difference YOUR GOOD !
Buy another 16 and two have a higher IR and say 10AH differential, that pack will be limited by the lowest common denominator which will be a runner that triggers either HVD or LVD by the BMS.
To make Grade-A the cells MUST match IR at all voltage test points under Charge & Discharge within the acceptable "Working Voltage Range" which is 3.000-3.400. (this is where the "real" AmpHours comes from) Most companies will actually do extended tests to 2.900-3.500. They do not test the "Allowable Voltage Range" which is 2.500-3.650 which is the safe margins for the cells without causing harm.
As for Battery Cell Reports, some stores do their own with whatever gear they have, is it done properly or not is unknown. Some only use handheld device like a YR1035+ https://www.aliexpress.com/item/32991434414.html? I happen to have one of these and it's fine for verifying the cells for IR. FACTORY Reports will ALWAYS Show the QR Data / Serial Number along with the test results.
My #1 Vendor is Luyuan and everyone who deals with Amy get's exactly what they order and with the EVE Factory Test Report
This RPT is from my last batch of 105AH Grade-A (sorry it's truncated)
Luyuan Tech :
Matched & Batched A Cells are FACTORY tested @ EVE as runs through the batches produced.
This is the TEST Report received From EVE with the full data, Translated to English where necessary for your convenience.
"OCV1" refers to the voltage of the cell (unit: V), which is the initial voltage of the cell tested by the OCV tester after eliminating the "polarization" of the finished cell;
"R1" refers to the resistance of the cell (unit: mΩ), which is the internal resistance (AC internal resistance) tested by the OCV tester after eliminating the "polarization" of the finished cell;
OCV3" refers to the voltage of the cell (unit: V), which is the initial voltage of the cell tested by the OCV tester after the finished cell sits some time at room temperature;
"R3" refers to the resistance of the cell (unit: mΩ), which is the internal resistance (AC internal resistance) tested by the OCV tester after the finished cell sits some time at room temperature
You buy 16 cells which all work and are close in IR (Internal Resistance) "generally" @ 3.000, 3.100, 3.200 & 3.400. They test out and there is no more than 5AH capacity difference YOUR GOOD !
Buy another 16 and two have a higher IR and say 10AH differential, that pack will be limited by the lowest common denominator which will be a runner that triggers either HVD or LVD by the BMS.
To make Grade-A the cells MUST match IR at all voltage test points under Charge & Discharge within the acceptable "Working Voltage Range" which is 3.000-3.400. (this is where the "real" AmpHours comes from) Most companies will actually do extended tests to 2.900-3.500. They do not test the "Allowable Voltage Range" which is 2.500-3.650 which is the safe margins for the cells without causing harm.
As for Battery Cell Reports, some stores do their own with whatever gear they have, is it done properly or not is unknown. Some only use handheld device like a YR1035+ https://www.aliexpress.com/item/32991434414.html? I happen to have one of these and it's fine for verifying the cells for IR. FACTORY Reports will ALWAYS Show the QR Data / Serial Number along with the test results.
My #1 Vendor is Luyuan and everyone who deals with Amy get's exactly what they order and with the EVE Factory Test Report
This RPT is from my last batch of 105AH Grade-A (sorry it's truncated)
Luyuan Tech :
Matched & Batched A Cells are FACTORY tested @ EVE as runs through the batches produced.
This is the TEST Report received From EVE with the full data, Translated to English where necessary for your convenience.
"OCV1" refers to the voltage of the cell (unit: V), which is the initial voltage of the cell tested by the OCV tester after eliminating the "polarization" of the finished cell;
"R1" refers to the resistance of the cell (unit: mΩ), which is the internal resistance (AC internal resistance) tested by the OCV tester after eliminating the "polarization" of the finished cell;
OCV3" refers to the voltage of the cell (unit: V), which is the initial voltage of the cell tested by the OCV tester after the finished cell sits some time at room temperature;
"R3" refers to the resistance of the cell (unit: mΩ), which is the internal resistance (AC internal resistance) tested by the OCV tester after the finished cell sits some time at room temperature
I’m in the process of doing this analysis - i feel it will take at least another decade to complete.
Anyone that tells you otherwise is demonstrably guessing.
perryfranz
New Member
So, one of the things that we can do to find out if (for any interest) we ant a GradeA cell is ask the test report, good to know.
In my case i'm building a small 8s of LF280k but i'm not gonna cry out as a baby if i do not get out exactly 7.168kWh because it's my first battery DIY and I want to make in practise all the theory I learned in the past two years of reading/watching everithing possible about batteries and solar. But unfortunatly I have to buy from EU warehouse and only a few shops have that, so Grade A or Grade B I have to deal with the famous 3 shops if I want to save some € instead of buing server rack batteries.
Maybe for my second battery and after have gained experience on this one I can become demanding on grade A cell, but based on review probably I can trust Dongguan Lightning or Docan, knowing that probably they are grade B... but for 8pcs circa 1200$ with duties and door to door from Germany... maybe they are not.
It is very important to be aware what you can expect and good to see you are aware of the situation on the market and do not expect grade A LF280K for 150 USD a piece from an EU warehouse! Whichever seller you choose, I would advice you to get from the seller as much information and assurance as you can - picture of QR codes, report of capacity, get guarantee of capacity or be told the capacity is not guaranteed etc. The more you get assurance and information upfront, the better. Once you'll have your deal done - let us know your experience.
It is very important to understand what is purpose of building the battery - if you're building a battery bank for yourself, for a set of PV solar panels then the B grade batteries may not be bad (unless you'll have some really bad experience getting the worst waste). Situation is different if you want use such battery as a part of project related to conversion of a gasoline car to an EV car (for instance). You should consider what you need in context of the project you have - if you foresee to stress the battery and looking for reliability, the better quality you want. If you're building battery bank for yourself and to use in a summer house - don't see need buy A grade, B from an honest reseller (who'll make basic assurance checks) should do fine. If you plan open EV conversion garage and offer modification of gasoline cars for other... no B can be accepted.
Steve_S
Offgrid Cabineer, N.E. Ontario, Canada
I very highly recommend Luyuan Tech, they are a Known Good Reputable vendor and they buy ONLY from Manufacturer and provide the Manufacturer's Test Report. Yes the Grade A cost a bit more but you get exactly what you are paying for,
Shenzhen Luyuan Technology Co., Ltd. - Lifepo4 battery, LTO battery
Shenzhen Luyuan Technology Co., Ltd., Experts in Manufacturing and Exporting Lifepo4 battery, LTO battery and 271 more Products.
szluyuan.en.alibaba.com
Also download THIS Resource about assembly & much more... Lot of info that will help you on your journey. It is also included with the batteries shipped by them.
Luyuan Tech Basic Lifepo4 Guide
This document was posted to the forum by Amy from Shenzhen Luyuan and written by Steve S. It was meant to be posted as a resource. Below is her description of the resource: Dear all friends in the forum, This file in the attachment was...
diysolarforum.com
Does Luyuan have warehouse in the EU? Perryfranz pointed he must buy from a vendor who has a warehouse in the EU.I very highly recommend Luyuan Tech, they are a Known Good Reputable vendor and they buy ONLY from Manufacturer and provide the Manufacturer's Test Report. Yes the Grade A cost a bit more but you get exactly what you are paying for,
Shenzhen Luyuan Technology Co., Ltd. - Lifepo4 battery, LTO battery
Shenzhen Luyuan Technology Co., Ltd., Experts in Manufacturing and Exporting Lifepo4 battery, LTO battery and 271 more Products.
Also download THIS Resource about assembly & much more... Lot of info that will help you on your journey. It is also included with the batteries shipped by them.
Luyuan Tech Basic Lifepo4 Guide
This document was posted to the forum by Amy from Shenzhen Luyuan and written by Steve S. It was meant to be posted as a resource. Below is her description of the resource: Dear all friends in the forum, This file in the attachment was...
To cut bullshit, EVE sells LF280K for $ 250 a piece. Whatever offers you'll see about grade A batteries bought from EVE and being sold for $ 150 - think twice about how they make money selling "the same", manufacturers, cells for 60% of manufacturer's price? 
apctjb
Solar Enthusiast
- Joined
- Jun 16, 2020
- Messages
- 480
Yup, no free lunch. If you are not paying +$200 USD per cell then regardless of the marketing claims you are unlikely getting EVE automotive grade cells. I just received 16 non automotive cells which I tested and have +280AH capacity and low resistance. Time will tell if I get the same cycle life but doing the math for my application if I get more than 4000 cycles I will be happy not to have spent $200/cell. Everyone needs to do the math based on their own situation.
I find it rude by Luyuan to take your work and brand it with their company name on every page but give you bare "Prepared by Steve_S..." on the bottom of first page - it looks like you work for them. Do you have some form of commercial connection with Luyuan?I very highly recommend Luyuan Tech, they are a Known Good Reputable vendor and they buy ONLY from Manufacturer and provide the Manufacturer's Test Report. Yes the Grade A cost a bit more but you get exactly what you are paying for,
Shenzhen Luyuan Technology Co., Ltd. - Lifepo4 battery, LTO battery
Shenzhen Luyuan Technology Co., Ltd., Experts in Manufacturing and Exporting Lifepo4 battery, LTO battery and 271 more Products.
Also download THIS Resource about assembly & much more... Lot of info that will help you on your journey. It is also included with the batteries shipped by them.
Luyuan Tech Basic Lifepo4 Guide
This document was posted to the forum by Amy from Shenzhen Luyuan and written by Steve S. It was meant to be posted as a resource. Below is her description of the resource: Dear all friends in the forum, This file in the attachment was...
Ok. In this situation, Luyuan should give him much more credit and distinction in the document he pointed.
houseofancients
Solar Wizard
isnt that up to steve ?
sjeez man, lighten up
The point is that it creates the false feeling that Steve works for Luyuan. That's it. I got the feeling and asked. It is up to Steve to accept it or not that people will have the feeling - very true. Case closed for me. However, Steve should answer himself - it is odd you speak in his name
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perryfranz
New Member
short long story (I have to create a new thread) I have an electric scooter equivalent to 125cc that I use to ride Home-work and now i'm only able to charge it during night paying 4 times the electricity than what enel (the Italian electricity distributor) pays me the power that I sell them via my ongrid 3kWh system (no, i can not add battery legally to it now and it's too expensive and time consuming modify the system... Italian burocracy..) Now we pay likely 0.4 or 0.5€ for kWh and they pay us circa 0.1€ for kWh sent on grid.
So the electric scooter takes only 3kWh every 3-4 days and with the 8S lf280 I can also power up when fully charge some cycles on our Miele washing machine (cotton 60°C takes around 1.5kWh) or maybe i can also use a few hour afternoon the split AC inverter to heat up my studios/home instead of use the naphtha furnace/boiler primarily (in the countryside is still common or LPG furnace/boiler) because in winter we obviously have less sun hour and when the sun goes down my ongrid system is useless.
i have 4 250W used panel (paid 55€ e.o.) found epever MPPT with great deal and now I'm trying to decide where buy those cells before buy the inverter.
end OT
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Very interesting to read your case but do I understand well that you see the battery being mainly for electric scooter and a back-up to some every day situations? It does not sound like a heavy use, what you plan. More like a light/occasional use. I would not be afraid of B grade cells, just do your due diligence - but that is what you are already on for 2 years so hope you'll be good.
Not sure from your description whether you plan somehow charge batteries from your PV set or buy when your energy supplier sells energy cheaper (for instance, at night). If you plan to charge the battery from your PV set then this is no brainer with the buy/sell price you provided. If you buy at night to use during the day, energy conversion coefficient is about 0.7 (grid -> charger -> battery -> inverter -> device) so worthiness of doing this depends. You know your use and daily routine so can run in Excel calculations but to me it sounds like DIY storage case, where the B grade batteries do fine and generally can save you money over time (likely you'll be charging the batteries, on average, less than once a day - you maybe will do between 50-200 cycles a year but that's what you should know best).
If I understood well, your PV set is directly linked to the gird, without use of battery - in this case, having some back-up battery can save you life if there will be power outage - as it is possible to happen if the war between Russia and Ukraine intensify during the winter time.
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Steve_S
Offgrid Cabineer, N.E. Ontario, Canada
Seriously You are a NOOBIE Here, I'm not, one of the first couple of hundred members.The point is that it creates the false feeling that Steve works for Luyuan. That's it. I got the feeling and asked. It is up to Steve to accept it or not that people will have the feeling - very true. Case closed for me. However, Steve should answer himself - it is odd you speak in his name
I also Did the Chargery BMS Manuals with the graphics works and all.
I got a few other Senior Members to help with getting the Chargery BMS' improved and helped with the development of their DCC's (Solid State Contactors).
I Edited & Revised the JK-BMS Manuals as well.
I've done docs, Manuals & Guides which are littered all over the place.
I have NO AFFILIATION with Anyone ! and received No Compensation for it. I ASK FOR NONE. I am NOT Ferenghi !
I've been an Opensource/Freeware/Shareware guy since the 80's ! If I'm interested in something and can do something to help others.
As far as Attribution I like to keep it low and always use my Site Username Name and in some cases even DIYSolarForum get's attached to it sometimes.
Lastly... I have what I need and do what I want, having been diagnosed Terminal with Cancer in 2014 and recently having spent 1 month + in critical care (I did the JKBMS manual then) and still helped folks here.
Yes Steve, I am NOOBIE here and feel good about this. As a NOOBIE can give you perception of how a NOOBIE can see things. Great to read you're a sharer and done so much for the people not being the Ferrengi [
] - that is much appreciated, that is what has greatest value in life, help and help develop others. Really sorry to read your situation. Sounds like you done a lot good things and God is about to take you to a better place. Those of us, who still not know the end, must still work to earn the place. I understand why others spoke in your name and seems like you got good friends here - that's a value! Given the circumstances, not sure we will have pleasure complement each other in helping others and learn from each other but pleasure to read people like you exist.If i wasn’t buying known cells from a manufacturer - based on my experience to date i’d do my financials based on 1500 cycles for LiFePO4.
I’ve seen too many grey market cells fail inside 6 years to have any confidence.
A lot of people i speak to are happy to get the 6 year lifespan too which is surprising as they paid more than half the price of a good cell that would have lasted twice as long.
apctjb
Solar Enthusiast
- Joined
- Jun 16, 2020
- Messages
- 480
Makes sense.
However in my case I purchased EVE non automotive (B) cells produced in April of this year on the same day, assembly line and they tested to +280AH and paid half the cost of automotive grade cells (which I could not get in the time frame I needed them) If 1500 full discharge cycles is all I get I will be disappointed but that's about 8 years in my application and by then I expect battery technology to have improved...
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