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B grade: damage to wrap possible, cells not matched, not advised for EV but fine for ESS projects.
New model, no datasheet available yet..
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Reviews
Customer Reviews
- Все добре Review by Pedko
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I waited a long time, but now the cells have arrived. I haven't assembled it yet, I haven't checked it, but they all have the same voltage of 3.17. So, I hope that the collars have retained their capacity and have no discrepancies in self-discharge. I recommend Nkon (Posted on 16-08-24)Rating - Works well Review by jean-claude
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In short: I am fully satisfied with the performance, The calls have no traces of usage, they are not bold, they keep their charge and have the advertised capacity. I ordered end 2022.Rating
This is my experience in building a roughly 9.5kWh PV storage battery:
I am using 16 of these cells. I ordered them end 2022 and had them lying around till late summer 2023 when I finally had time to work on my PV project.
The cells are definitely not from one batch, some have square rectangular aluminium pads (as in the product description's photos) with the studs soldered on, some round pads with the same studs. The cells are sold with nickel coated copper bus bars and stainless steel nuts. All cells were in good condition with similar internal resistance and around 3.252V to 3.257V of charge (resistance and voltage measured using YR1035+). I considered these cells were good to proceed.
I hooked them up in series using a jkbms, charged them up slowly, let them balance using the BMS's active balancer and settle for 24h. The cells had then voltages between 3.347V and 3.352V. I let the charged cells then sit almost unused for one month (I occasionally drew 25mA for some light while working on the installation). After the month the Voltage of the cells was between 3.334V and 3.337V. The BMS's balancer was switched off during this period to discover poorly performing cells. I considered that there was no leakage and that the cells keep their charge as expected.
I then fully discharged the cells,charged them up again and drained them using electeic heaters as fast as my installation allowed it with about 68A for almost 3h. I measured 186.5Ah drained from the battery when the undervoltage protection of the BMS stopped the discharge. I consider the cells capacity as advertised.
(Posted on 06-01-24)
Write Your Own Review
B-grade cells are cells usually did not qualify as A-grade by the manufacturer. This may be due to optical imperfections, higher self-discharge, lower capacity and/or higher internal resistance. Unfortunately manufacturers don't tell which aspects or aspects are the reason to mark a a specific cell as B-grade. We have sold several and get seldom negative feedback. We tested several eve B-grade and one had about 2% lower capacity, the other ones we did not find a difference with A-grade cells. We don't advise B-grade for high performance electric vehicles but for home energy storage they will work fine. In case you get one which performs significant less than the others like lower capacity, high self-discharge or fast wear we will replace it. Take care that we don’t put a lot of trust in a simple test of a single cell, if you buy 16 cells and you test them and they are all 6% lower than expected then your test gives to low results. If you buy and test 16 and 15 cells give you 100% and one cells gives 5% lower results then we will replace one. When we buy cells the cells are tested for voltage and internal resistance. Also a couple of every batch are tested for capacity, and if one gives less than 100% capacity we test the whole batch and discard the bad ones or don't buy the batch at all. Lot of seller in china buy B-grade cells, test them, even swap qr-codes and sell the good looking and performing as A-grade cells. We believe our B-grade cells are the same as lot of A-grade cells from China, including the well known resellers there with good reputation. We give regular warranty on these cells (at least 2 year).
