So you want to know what you are buying? A, B or even C grade battery cells. Well, the truth will likely shock you. But a typical failure rate for cells in the 200AH+ range is currently between 2-10%. For a Tier 1 manufacturer live CATL, EVE, CALB the rate is lower for example 2-4%. For tier 2 and 3 manufacturers it can reach 10%. And it’s this high, because it’s very difficult to produce cells of this size perfectly.
For reference the reject rate on 18650 cells by Panasonic, and Samsung is more like 0.001%. So, you can see there is a huge difference
So what makes a cell A Grade?
Testing over a period of about 3-4 weeks, it is done in the factory, the cells are cycled multiple times, with an initial charge that is also to electroplate the lithium onto the cathode and anode. One of the best test’s used is the X-RAY test, and this test in particular allows the manufacturer to see into the future. And see obvious problems early.
It’s what differentiates the A grade and B grade product, As we have always known, A good B grade product is likely to only last somewhere between half to 1/8th of a good A grade product, however this does come many caveats, especially to do with how the cells are managed and treated in their service life.
IF YOU TREAT THEM POORLY they will degrade much faster
Some of the brands that make the same LF280 and LF302 cell are CATL, EVE, Li Shen, Hithium. CALB, Ganfeng, ETC, Sundowa, REPT and actually a few more. This is an identical cell, only the defect rate and quality of the chemical composition are varied, things such as the purity of the Lithium Carbonate vary. It’s a little bit like the paint job you might get across different car manufacturers. Making Lithium cells is extremely precise. All the machinery must be running at the optimum in order to get the defect rate lower.
Where do all the A and B grade cells go?
A grade goes mostly to Electric Vehicles. Trucks, Buses, Cars, Trains, but also for Grid Storage, for homes and sometimes even RV’s and Caravans. They also go into some brand name products, such as Victron, Bluetti, Roypow, and our own brand LiFePro.
Why do they sell B grade?
One of the challenges that battery manufacturers face is the quality control of their products. Not all cells are created equal, and some of them may have flaws or defects that prevent them from being used in vehicles or other high-performance applications. These cells are usually classified as Grade B or lower, and they represent a significant loss of revenue for the producers. However, there is still a market for these lower-grade cells, especially for less demanding uses such as power banks, solar generators, or DIY projects. The LF280 and LF304 are two examples of large-format cells that have a high defect rate, up to 10%, which means they cannot meet the strict standards for vehicle use. But they can still offer a decent capacity and power output for other purposes, and they are sold at a lower price than the Grade A cells.
B grade cells are a common choice for stationary applications, such as DIY battery projects. Unlike C grade cells, which often have visible flaws and may come from recycled sources, B grade cells look flawless and have minor internal defects that do not affect their performance significantly. There is no regulation that prohibits the use of B grade cells for battery storage, and many people take advantage of this to build their own battery packs at a lower cost.
If you are wondering who is the judge of B and C, well that is something that has emerged over time, across the industry, they needed a way to label the quality of the cells, as the buyers become more educated especially with the forums such as DIYSOLARFORUM hosted by Will Prowse in the USA.
My personal opinion of forums and Facebook is that they are not a good place to get accurate information
The lithium battery industry is complex and constantly evolving. I have spent years studying it and updating this article several times to keep up with the latest developments. Don’t trust everything you see on Facebook. Most of it is outdated or inaccurate, and distorted by repeated sharing.
EVE marking the letter B on cells?
As we have been in communication and sales with EVE over the past 48 months, we have a direct line to the inner workings of the EVE battery cells.
- The price of new A Grade EVE cells is about 50% more expensive than can be purchased in B grade
(January 2024 update: the cost of Automotive grade is currently about the same for us at Lifepo4 Australia, very unlikely this will last more than a few months but it’s because the manufacturers, EVE, CATL, etc, have dropped the prices significantly in December and January) - EVE’s brand is very valuable to them, and so they are printing the letter B on all cells that don’t meet the grading cut for what we know as A grade cells. This is something they have not done in the past. And all new stock from May 1 2022 will be marked with the letter B if it is not an A grade product.
- MOST SELLERS ARE REPLACING or RE LASERING QR CODES, Unfortunately, it is already very easy to find cells without the B etched into the QR code. And if you aren’t educated you are likely buying B grade cells, that you are told are A grade.
- January 2024, there is now a lot of B grade cells being sold as Automotive grade. Every Alibaba vendor we contact is faking the QR codes.
The only way to know for sure is to buy directly from EVE, or Lifepo4 Australia.
If you are in the USA, you can go to SFK, or 18650 Battery store.
- We also know that in these LiFePo4 factories there is always 2-10% of cells that don’t meet the cut for what we refer to as A Grade.
December 2023 update : We have now learned that when a factory opens it goes through a period of months where as many as 50% of large cells such as the 300ah, are classed as B grade. This yield continues to rise until it reaches about 85-90%. We finally have an answer to how there are so many B grade cells on the market. - A Grade cells can be for cars, Electic Buses and Trucks, along with BESS (battery energy storage system) use where the C rate maybe higher than 0.5C
- Remember that EVE is a much larger company than you might realize, they have multiple factories of different ages, and as each factory is built, the technology is upgraded to be better than it was in the past. For example its very likely the new Version 3 cells are a new factory altogether!
More Evidence? I hear you ask. So what is the grading process?
Let’s use A Grade EVE LF280K cells as an example. EVE has not confirmed what the grading process is in writing, but it is a mixture of things
- Voltage at rest
- Voltage under load
- Voltage recovery
- Appearance
- Internal Resistance
- Capacity
- X-RAY Test
- An LF280K v3 is likely to need to pass 300AH in capacity at a 0.5C rate to meet the requirements for Grade A. In other words, it could be from 300-310AH in capacity when brand new to be what we call an A Grade.
- Occasionally an Automotive grade cell can actually test under 300 AH but have excellent voltage. This is because technically they measure the cells in Watt hours and not amp hours. But for simplification, I’ve just adjusted the numbers as they are what we typically receive.
Many YouTubers mistakenly believe that if they discharge at a rate of 0.2C that is how they can get the accurate capacity. This is partly wrong because the cells are tested in the factory at either 1C or 0.5C. This 0.2C discharge is not what the factory specifies in the datasheet, sometimes this is referred to as storage battery grade, but the truth is, that’s an invented term, to allow the resale of cells that failed from the factory according to the specification sheet and test results.
DATASHEETS are very often faked on marketplaces, and forums, and especially from poor quality sellers, looking to take advantage of anyone who isnt an expert.
B grade cells can have almost the same capacity (in Ah) and impedance (internal resistance) as Automotive grade cells WHEN they are brand new, making it difficult to distinguish between the two. B Grade cells are 30-40% less expensive than Automotive grade cells.
B grade cells are normally sold to Chinese companies for use in Solar storage, that is how they end up on Alibaba the buyers will do spot checks on the cells, almost never will they test all cells, as it is cheaper to send the odd warranty replacement than it is to test them all.
They are then resold on Alibaba as A Grade, and I’m yet to find any seller who doesn’t call them A grade (that should tell you something). this is the reason why 90% of cells sold in Australia are actually failed or rejected cells, because no one, ever wants to pay the price premium. It’s just how it is. And only the most experienced buyers, order our A grade product from a professional seller, or directly in bulk from the factory. Usually with very high shipping charges. I recently obtained a quote for 20 x EVE LF280K v3 cells and the shipping was over $1500AUD alone. Not including the battery cells themselves.
This is just robbery. This along with a warranty that is useless as you can’t return lithium battery cells to china without extreme cost and dramas, meaning you are just about always better choosing an importer to purchase from, as they are held to Australian Consumer Laws, and must supply a warranty that is reasonable. For Automotive grade cells this might be as long at 5 years.
When you compare costs on the international market to prices on NMC and LFP cells imported in Australia, it’s easy to see that a significant portion of the NMC and LFP cells imported are B-grade cells. One of the main reasons for this has been fierce price competition among battery pack assembly businesses, and this is an enormous growth industry. From 2015 to 2020 the number of factories rose from 4 to 181. And this is accelerating, almost every week, there are multiple announcements of factories 10 times the size of previous ones.
Certified A Grade vs. B Grade Cell Performance
Fade/Cycle Life of Capacity – A lithium-ion cell’s cycle life is defined as the number of charge-discharge cycles at 80-100% depth of discharge (DoD) until the cell’s retention capacity reaches 70% or 80% of its initial capacity. B grade cell’s capacity fade is higher, which means it has a shorter cycle life. When compared to A grade cells, B-grade cells have a faster rate of capacity fade, which can be anywhere from 50-90% faster. That means that if an A-grade cell is designed for 11 years of life, which the LF280K is expected to last to 80% capacity. A B-grade cell might hit that point at anywhere from 2 to 5.5 years. There of course are many factors at play, but you can do some math, and work out the TCO (total cost of ownership) from this information.
My personal view is that there is no magical new chemistry that will overtake Lifepo4 in the next 5-10 years. with Sodium-Ion batteries slated for mass production from 2023 onwards, and very unlikely to be at cost parity until around 2028-2030. And then they may be only 20% cheaper, but at this point in time, I cannot predict the future with any certainty.
LEAD ACID vs LFP?
Lead-acid batteries are no competition to LFP. They are inferior in every possible way.
LEAD-ACID AGM | LITHIUM-ION | |
|---|---|---|
Installed capacity | 100 KWh | 50 KWh |
Usable capacity | 50 KWh | 50 KWh |
Lifespan | 500 cycles at 50% DoD (Depth of Discharge) | 8000 cycles at 100% DoD |
Number of installations | 6 (1 + 5 replacements) | 1 |
Battery cost | $60 000 ($100/KWh x 100 x 6) | $12500 ($250/KWh x 50 x 1) |
Installation cost | $12 000 ($2000 per install x 6) | $12500 (one shot install) |
Transportation cost | $6 000 ($1 000 per transport x 6) | $1 000 (one shot install) |
TOTAL COST | $78 000 | $13500 |
Cost per usable KWh per cycle | 0.42c / usable kWh (78 000 / 3000 / 50) | 0.031c / usable kWh (23 000 / 6000 / 50) |
In summary, the total cost of ownership per usable kWh is about 10 times cheaper for a lithium-based solution than for a lead acid solution. And that is not taking into consideration the huge losses due to absorption, you would need to size your solar system at least 30% larger with the best Lead Acid System. Meaning even more additional costs!
It does NOT make sense
Do you want to know more about Internal Resistance?
Impedance, commonly known as internal resistance, is inversely proportional to cell performance. The lower the impedance, the higher the charge and discharge rate of the cells. Because electric vehicles require rapid charging and high power discharge, EV Grade cells have a lower impedance than Energy Storage Grade cells.
The impedance of the cells increases when they are charged and discharged. The cell’s impedance reaches a threshold where it is no longer usable for a particular application (such as EVs). It is then disassembled and utilised as a part of a second-life battery to power applications with a lower charge-discharge C rating (such as Energy Storage Systems). The rise in the number of B grade cells is faster than the rise in the number of A-grade cells.
References
GB/T 31485-2015: PDF in English. (chinesestandard.net)
SHIPPING and Verification of our cells
Our warehouse in China packs our cells into boxes of 2 or 4pcs for easy delivery in Australia. EVE supply our Bulk A grade purchases. This is done for ease of shipping, as per the regulations found here link. UN3480
EVE data is supplied with True A grade product, it’s unmistakable, its supplied in an excel spreadsheet, and contains the QR code, date of manufacturer, location of manufacture and other important information. We will give you a copy of the original EVE data. Usually part of a larger order, sometimes as large as 800pcs.
You can then contact EVE yourself to verify the QR codes should you have a reason to do that.
WE ARE NOT GOING TO PUBLISH THIS DATA ONLINE, BECAUSE OTHER COMPANIES WILL ATTEMPT TO COPY IT
All Lithium batteries are dangerous goods and, as such, require special packaging for transportation.
All domestic and international shipments containing lithium batteries are subject to transport regulations on hazardous goods according to ADR RID, ADN, IMDG, ICAO / IATA Regulations.
The batteries UN3480 are lithium-ion batteries, rechargeable, without equipment.
The lithium-ion batteries UN3480 are classified:
Class 9 – UN3480 – Lithium-ion batteries – Batteries that are not packed with or installed with the equipment.
For each model of battery, there are different requirements to be verified:
– Type of battery.
– Weight of the battery.
– Dimensions of the battery.
– Capacity of the battery.
– Mode of transport.
