The chaos of battery cycles and Micergy’s recommendation for buyers

Welcome to Micergy's latest insight on ess and e-mobility, today, let's talk about some sensitive issues of the battery sector --- the battery cycles.

For batteries, cycles are one of the most important factors considered by customers, different types of batteries have huge differences in life cycles, for example, the LiFePO4 batteries are known to have a super long cycle compared with lead acid batteries, however, what if different cycles are offered for the same LiFePO4 batteries, how can you tell? different suppliers are offering different promises on cycles, some are real, and some are playing word games, so why does this happen and what can we do?

So when facing a client that is not familiar with this sector, the marketing language attracts more attention compared with the technical language, for example, when provided with the option of 10,000 cycles and 6,000 cycles, what’s your choice? The choice for most people will be the former, especially with the cost of lithium going down substantially, the market becomes a buyer’s market, and the seller are trying their best to attract more attention from the buyers, in the buyer's market, if you don't speak according to the customer's logic, the customer will abandon you, sometimes, it’s unfair for supplier with technical language.

A charging cycle is completed when a battery goes from completely charged to completely discharged under certain test conditions.

As we all know, this is the technical explanation of the cycle, however, technical language is not the same as marketing language for most suppliers, some suppliers define the charge and discharge cycles by fully charged and discharged, and some calculate the number of battery charge and discharge cycles by using the accumulated total charge and discharge when the battery is shallowly charged and discharged, it’s obviously that the impact of shallow charging and shallow discharge on battery attenuation is less than that of full charging and discharging, that’s one of the reasons why some supplier a 10,000 cycle warranty for their battery system when using battery cell with 6000 cycles.

Most suppliers' warranty promise comes from self-assessment and prediction after initial cycle testing, instead of actual measured data.

So why is warranty promise not supported by actual measured data?

Let’s take an example of the energy storage system, the battery cell cycle test, if the charge and discharge test is performed at a rate of 1C, a complete charge and discharge cycle plus the cooling interval between charge and discharge theoretically takes at least 3 hours. Assuming that automated testing equipment is used, a maximum of 8 charge and discharge cycles can be tested throughout the day, and 2920 cycles per year. 10,000 cycles theoretically require nearly 3.5 years of testing time; 15,000 cycle tests theoretically require nearly 5 years of testing time, the reality is that so many new players came into this industry in less than 5 years, how can they finish the test and provide the warranty based on the actual measured data? Besides, technology has leapfrogged in past years and the energy density is improving all the time, new products with bigger capacities but small or the same size are unveiled frequently, the market won’t wait for the actual measured data to grow, and rigorous battery cycle testing takes a long time. The common practice in the industry is to test the first 2,000, 3,000, and 6,000 cycles, etc., and the subsequent cycle test results use the company's self-assessment method to give a coupling curve of battery cycle and capacity attenuation. In addition, there are also some "equivalent" test methods that increase the charge and discharge rate to speed up the test process.

What makes things worse is some battery suppliers may pack the battery with the used dismantled cells or modules from the EV, but claim to be brand new cells and give a warranty like the grade A cells, and it will be difficult for the buyer to find the problem when using it in the beginning, however, the problem will come out after certain time and the battery performance will drop sharply, We do recommend all buyers to pay attention to this point to avoid potential loss on serious aftersales problem.

Is there a way to protect the buyers on battery cycle warranty to some extent?

The answer is yes, At Micergy, we listen to the market and understand the battery should be durable goods to be used for years, just like the car with mileage, the battery has cycle counts, we innovatively added battery cycle count to the display of our battery energy storage system, which will show historical accumulated battery cycles, so the end-users are well aware of how many cycles their battery has been used and how many cycles left, the battery cycle count also provides an easy way for the local dealers or buyers to do the battery recycle and evaluate the value of the batteries when the end-users plan to sell it, just like the car mileage for used vehicles.

About Micergy

Micergy started lithium battery manufacturing in 2009 and provides custom lithium battery products for different sectors, including energy storage batteries, lighting electric vehicle batteries, and custom batteries for golf carts, Marine, RV, and Forklifts. Besides, not limiting ourselves to the R&D of BMS to protect the battery and lengthen the lifespan, relying on the competitiveness of the battery, Micergy further embraces the IoT technology and developed comprehensive 'Energy + IoT' solutions for various sectors to solve the affordability problem of product with a high upfront cost.

Welcome to visit www.micergy.com or drop an email to [email protected] to learn more about Micergy custom lithium-ion battery products for the energy storage sector and e-mobility sectors.

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