We have some more news in regards to very popular A and B and C grade cells coming from EVE Energy in china.

As we have been in communication and sales with EVE over the past 12 months, we have a direct line to the inner workings of the Alibaba EVE battery cells. The price of new EVE cells is about 30-40% more expensive than can be purchased on Alibaba. We have also been told by EVE directly that their brand is very valuable to them, they are now going to be 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 June 1 will be marked with the letter B if it is not an A grade product. We also know that in a Lifepo4 factory there is always 2-10% of cells that don’t meet the cut for A Grade. A Grade cells are reserved for commercial BESS use, and for EV and Electric Buses predominately. Remember that EVE is a much larger company than you might know, they have many factories of different ages, and as each factory is built, the technology is upgraded to be better than it was in the past.

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 mix of appearance, internal resistance, and capacity that they use to grade the cells. An A grade cell is likely to need to pass 289AH in capacity at a 0.5C rate to meet the requirements for Grade A. In other words, it could be from 289-300AH incapacity to be an A Grade cell.

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 basically wrong because the cells are tested in the factory of either 1C or 0.5C.

B grade cells have almost the same capacity (in Ah) and impedance (internal resistance) as A grade cells when they are brand new, making it difficult to distinguish between the two. B Grade cells, on the other hand, are 30-40% less expensive than A Grade cells.

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.

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% depth of discharge (DoD) until the cell’s retention capacity reaches 80% of its initial capacity. A 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.

Lithium-ion batteries are noted for their long lifespan. The cells degrade over time and their energy storage capacity decreases, but they last a long period, unlike lead-acid batteries, which die suddenly. After a period of time, B grade cells are prone to sudden death failure.

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.