casualobserver: I am sorry but that is BS. I am not a pro but in my quest to build a solar system I have had to watch a lot of YouTube videos, read a lot of solar forums and followed this section on Nairaland as it is clear there is a lot of cowboys, quackery, ignorance, misinformation and “anyhowness” in the Nigerian solar space, this is even before those who just want your money and will tell you anything to get it. I have been to a well known solar installer with its own OEM branded axpert products that couldn’t tell me the brand of lifepo4 cells in the lithium batteries they sell.
Cells are either Certified Automotive grade or they are rejected cells. Any rejected cell is a grade B cell. Once you are dealing with rejected cells (which could be rejected for a number of reasons) you are on your own. They may be cells good enough for home storage but not for the automotive demands or they may be outright bad cells.
1. QR code means nothing as they are faked 2. Eve started stamping their Rejected cells with “B” grade on the QR code but Chinese resellers have found a way to “remove” the “B” stamp. B does not mean a cell is bad, however the problem with B is that it can be good or it can be bad. Most A cells on the market are B cells, so they could be good or they could be bad. 3. That a cell tests ok for capacity does not mean it is a good cell. Many cells will test ok for capacity but will drop voltage under load. Just like a bad lead acid battery, it depends on the load on it. I will post a video below highlighting this. 4. Your battery is only as good as the worst cell in your pack. If there is one bad cell it will bring the whole battery down. 5. There is nothing wrong with the better “B” grade cells for ESS (which people falsely call A- or outrightly sell as “A” but you need the r Test reports so you know what you are dealing with or test them individually and match them for voltage, capacity and internal resistance. Otherwise the cells start to deviate as you charge aand discharge due to different internal resistances of the cells and before you know it the individual cell voltages go out of whack, your BMS is shutting off charging or discharging because one cell is hitting low or high cut off voltage before the others and you are not getting the available capacity you have despite having the capacity. Cells with different internal resistance will discharge at different rates to each other. So you see it is not just about putting cells together with the same capacity. We need to know what the internal resistance of the cells put together are…hence the need for matching. 6. What you need for any cell is the manufacturers test report. Do not buy a cell from anyone without a manufacturers test report. You need that to match the cells in a pack. QR code even if legit is meaningless on It’s own. what you need to assemble a battery is consistency/matching of the cells so the cells charge and discharge in unison. 7. When you see a battery with a recommended continuous charge/discharge rate of less than .5c it is a sign the battery contains poor grade cells. The popular lithium batteries beginning with “F” is an example of this. If you check the specs of reputable batteries like pylontech or BYD. You will see they are .5c continuous. There is a reason they cost more. Also a sign of poor grade cells is when a battery has its cut off voltages limited in the BMS or you are restricted to 80% capacity to keep the cells in the flat range where the voltages will not diverge due to inconsistent cells. 8. Again the overwhelming majority of these batteries are not certified grade A but some can be used so long as they are matched for capacity and internal resistance and for peace of mind you need the manufacturers test report. QR code means nothing when putting cells together. I was watching a YouTube video only yesterday of a guy in the US who actually makes and sells batteries and he says even from his reliable Chinese cell supplier, sometimes 4 out of 16 cells will be bad cells and if you are buying from these suppliers buy 20 if you need 16. Unfortunately I can’t find the video. 9. If a cell is not certified automotive grade, it is a “B” cell. If it is certified automotive grade, it will have a manufacturers test report. There are good “B” cell, many reputable battery manufacturers assemble good reliable batteries with “b” cells after carefully matching them and many resellers would the world a lot of good if they just say these are good “b” cells with the matching documentation and test reports. The minute someone is telling me a cell is “A” grade A- or whatever and has no test report, he is either ignorant or lying to me. Every cell whether A or B has a test report. If it has no test report you have to ask why is your reseller not willing to show you the test report. Assume any cell without a test report is a B cell because if you have a true “a” grade cell you won’t need to ask before you are shown.
mank1234: When you tell them your price they will run to the other person. And when the real experience of poor quality comes after the sweetness of low price, they will come there to generalize.
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ajabani4allah: My Dc celling fan has been failing but it stopped working completely yesterday and during my testing I discovered it's the driver board that's faulty. Pls who know where I can get the board below
I can get it for you. I just need to destroy one fan @12k
Satellite TV Technology › Re: Solar Energy, A Complement To FTA by JUO(m): 7:29am On Oct 27, 2023
