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  1. Y

    Leaked : New 26 and 65Ah LG cell datasheets for EV - LG E63 (Renault Zoe) and C1.5S

    @TilmanBaumann The most optimized way to charge LiIon cells is to use constant polarization voltage (20 to 100mV). All EV manufacturers use this method as the base for their charging algorithms. That's why the LG datasheet is so specific about SoC vs OCV. Betwwen 10 and 30% SoC, the cells can...
  2. Y

    Leaked : New 26 and 65Ah LG cell datasheets for EV - LG E63 (Renault Zoe) and C1.5S

    Hello, I just came across these 2 datasheets on QB's website. Both are clearly addressing the EV and residential storage market. E63 is ~240Wh/kg and C1.5S is ~170Wh/kg. It seems like the 65Ah model is the current (or future ?) Renault Zoe battery cell : the datasheet explicitely mentions 22...
  3. Y

    DIY battery pack cooling

    What I did on my 10S and 14S ebike packs is varnish the entire pack internals and close the ends with wire mesh. This allows air circulation in the pack and repells big debris. Rain/water can get in and out. Tested for 1 year without trouble and no corrosion ! Airflow is critical to quickly...
  4. Y

    Voltage drop with acceleration

    Considering the effort you put in making these packs and the safety risks, I would first learn how to make a pack properly. You seem to have good DIY skills so here are some guidelines : - Cells must NEVER touch each other. Use spacers ("battery holder") instead. That's to prevent overheating...
  5. Y

    Samsung INR21700-48G

    @ElectricGod : your conclusion reach mine ! These cells are overpriced and useless. I think they are 35E chemistry fitted in a larger case : when you normalize numbers and curves proportional to the cells mass, you get the same (=poor) cycle life and slightly more saggy discharge curve. When...
  6. Y

    CHEAP NEW ORIGINAL 18650 21700 BATTERY CELLS, POUCHES AND PACKS

    @tomjasz I have bought these cells from Tumich last year. I put one in accelerated testing 4.01 to 2.8V /6A. After 1100 cycles it was still giving >2800mAh under manufacturer test conditions. And in real life, my commuting ebike that has seen approx 60 cycles in a year still outputs 95% of its...
  7. Y

    Samsung INR21700-48G

    @ElectricGod : good to see you took the plunge on these. What decided you on the 21700 format ?
  8. Y

    Any Tesla 18650 data sheets available from years gone by?

    Do you have cycle life test data for HG2 cell ? I've performed some tests of Samsung 30Q cell but not HG2. Not great cycle life but no degradation of internal resistance over time. I tested 30Q in priority based on this test (quite extreme ! cells reached 80C)...
  9. Y

    Any Tesla 18650 data sheets available from years gone by?

    Nice link ! Will watch the video in full when I have time. I've seen a few papers about EIS testing for various Liion cells evaluation purposes, including online SOC estimation. It's beyond the effort I am willing to put in my personal testing. These tools must be really valuable to battery...
  10. Y

    Cycle life testing : LG INR18650 MJ1 vs Sanyo NCR18650GA

    I stopped testing at ~1100 cycles. Interestingly the capacity retention under manufacturer's testing conditions is excellent. Less than 15% degradation in 1000 cycles. For LG MJ1 the Coulombic capacity degradation is predominant For Sanyo GA the internal resistance degradation is predominant...
  11. Y

    Any Tesla 18650 data sheets available from years gone by?

    In my testing the cells are charged at 1A (0.3C) CC-CV to 4.19V and CC discharged at 9A down to 2.8V, then CV discharge down to 3A/2.8V. The tester is a fully calibrated iCharger 4010. The test method is not conventional, because I tested these cells for a very specific use case. But what I...
  12. Y

    If you are building packs today, which cells to choose?

    35E has very very bad cycle life ! And it sags a lot more under 10A discharge. Its initial capacity is the highet of the holy trinity GA MJ1 35E but after 20 cycles it becomes the worst.
  13. Y

    Dunk charger in boron nitride?

    You want to use hBN or cubic ? problem with encapsulation is that you will put thermomechanical stress on the components and end up with a failed charger in few months. Better solution would be a sealed aluminium enclosure filled with oil at 90% (to accomodate thermal expansion in the...
  14. Y

    If you are building packs today, which cells to choose?

    Samsung 30Q for excellent high-rate performance during the whole life of the cell Panasonic 18650BM for excellent cycle life, safety, overall performance and value (Tesla cell) Sanyo GA for best initial performance but heavy internal resistance degradation over time
  15. Y

    Speculate what happened to my cells

    If the cell suffered from overheating (probably not the case here), Hydrogen Fluoride may have been formed by thermal degradation of the LiPF6 electrolyte. So I would recommend you to NEVER smell battery gas, since HF is lethal at ppm levels. Though in your case it's probably just CO2 and...
  16. Y

    Need Help Selecting Battery for TSDZ2 36V 350W

    Don't worry about the connectors ! Just cut the battery and motor wires and use whatever connector you want. I have XT90S on my bikes. They are large enough to disconnect using gloves, can handle 50A and best of all : they have an integrated resistor to prevent the spark during connection...
  17. Y

    mean well rpb-1600, programmable charger ~1600w

    Good find !! The PMbus potentially means we can control this with an Arduino and use whatever charging strategies we want ! 300USD is not shocking, power supplies are so expensive.
  18. Y

    boston swing 5300 battery 3000 cycles

    I have bought 6 of these cells and started testing them. Initial capacity was 5200mAh. 3000 cycles is probably a lie. Different versions of the datasheet show different cycle life graphs ! After 50 cycles they just look similar to brand cells, not better (not worse either !). The degradation...
  19. Y

    tesla battery temp monitor

    In fact, Linear Technology has a more pragmatic approach to this. In their LTC680x application notes, they suggest using diodes in series/parallel to monitor individual cell temperatures. Each cell has its diode and a few diodes are placed in // to make a diode bank to be compared to others...
  20. Y

    Bridge-less PFC isolated 99% efficiency capable charger

    The Renault Zoe also uses the inverter as fast battery charger. Don't know anything about its detailed implementation.
  21. Y

    Samsung INR21700-48G

    I have some of these 48G. Pretty uninteresting cell after all. It behaves exactly like the Samsung 35E, i.e excellent initial capacity, extremely poor cycle life and very high internal resistance (worse than 35E in fact). When you normalize the results by cell mass, their behavior is...
  22. Y

    Any Tesla 18650 data sheets available from years gone by?

    Tesla cells in the model S are clones of the the NCR18650BE and NCR18650BM cells. The BM is essentially a slightly improved BE. These cells are state of the art, not because of their initial capacity (which is average+) but because of their excellent cycle life, tight cell-to-cell dispersion...
  23. Y

    Battery Failing Under Load?

    I would suspect a faulty mid drive. There is no reason for your battery to suddenly work like crap unless many cells inside are disconnected and unbalanced. It could be a hall sensor fault, winding fault, wiring fault, bad solder joint on PCB, damaged MOSFET... Do you have the possibility to...
  24. Y

    The 3500mAh heavyweight division: Sanyo NCR18650GA vs Panasonic NCR18650GA vs LG MJ1 vs Samsung INR18650-35E

    Perform the same test after 300 cycles and you will be surprised with the results ! GA is excellent in the first 50-100 cycles but the internal resistance rises so quickly that even an old 18650PF beats it after that.
  25. Y

    Boston-Power Swing 5300 Li-ion cell test

    Nice to see they have 2 flat sides ! Makes the pack more energy dense per unit volume and also easier to liquid cool ! Also the vent notch on side is a cool safety feature, at least the sidewall failure location is predictable. But the inside visible in this post ...
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