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  1. M

    Cycle life tests of High Energy density cylindrical cells

    This is very nice results. I like the internal resistance staying at a low level. In my experience IR seems to become a problem before capacity loss. Had this problem especially with nca cells.
  2. M

    bluetooth BMS?

    Found the problem. Battery negative balance lead had broken.
  3. M

    bluetooth BMS?

    nBG5qz9Wm_s What's going on here? Cell group 1 is jumping up and down and it's going in and out of high and low voltage protection mode. I ripped the battery open to check the actual voltage of cell group 1, and it's at 4.1V thankfully. This is a little scary.
  4. M

    Li-ion cells cycle ageing

    Strange that all reputable sellers lists vtc6 as a nmc cell. In fact the study you are pointing to is the only result I can get from searching vtc6 plus nca. It just goes to show one can't be sure about anything. It was my understanding that nca was not ideal for high discharge cells.
  5. M

    Li-ion cells cycle ageing

    I think he referred to the 3 cells in the study I linked to. In the study all 3 cell types lost about 3% in 10 months at room temperature under 60% soc. So it's not too far off their results.
  6. M

    Li-ion cells cycle ageing

    You are right about the comparison of course. Although I recognise the trend of nmc cells having less rise in IR etc. They have some basic differences in chemical buildup. But then again, some HE cells show even worse cycle life than mentioned HP cells, like panasonic PF and sanyo/panasonic GA.
  7. M

    Li-ion cells cycle ageing

    VTC6 is definitely NMC, I don't think the LG cells are NCA either.
  8. M

    Li-ion cells cycle ageing

    That's a fairly rapid decline. In many applications, calender ageing will render it useless before cycle wear. That might be why tesla is sticking strictly with NCA chemistry for electric vehicles? NCA has always been touted to have superior calendar life. According to this study the...
  9. M

    Li-ion cells cycle ageing

    Vtc6 seems like one of the very best cell to consider for high amp applications. You really can get both high power and high energy these days. What's the drawback? From what I can see from my own experience and what I can read online, calender degradation only seem to be a problem if stored...
  10. M

    Li-ion cells cycle ageing

    Cool! Will you sell me your testing equipment for cheap then? Since you won't be needing it anymore I mean :wink: Sad to loose you as a resource though. Your work is really interesting. I'm sure a lot of people would chip in a few $ for your work if you had some sort of donation thing going...
  11. M

    Li-ion cells cycle ageing

    Any idea why the cells have lost more capacity percentage wise inside the cycling interval than total capacity degradation? Have you tried retesting the cells with the previous parameters after it has been fully cycled to see if some of the capacity within the cycling interval has been regained...
  12. M

    Li-ion cells cycle ageing

    Sharing ideas for future tests is not being entitled. I'm sure he's going to continue testing cells in the future anyway. The effort put in here as well as the execution is amazing, and I am very grateful for it! Having this many different cells tested at the same time is gold. Comparing cells...
  13. M

    Li-ion cells cycle ageing

    I would also like to see at least some of the cells tested at 4.2v. With this much great information it is a golden opportunity to see what difference 4.1v vs 4.2v actually makes with the other parameters being the same.
  14. M

    Li-ion cells cycle ageing

    What happened to the chart? I get this error: "The selected attachment does not exist anymore"
  15. M

    Annual Battery Capacity Test

    Okay. I don't give my batteries enough cycles to cause a lot of capacity loss either. But I have noticed increased IR with resulting voltage sag after a few years. Also when removing cells from old laptop batteries etc they are ofte close to their rated capacity but with very high ir. Could be...
  16. M

    Annual Battery Capacity Test

    A few years later.. It seems like your batteries have lost no capacity at all after the first year 🤔 Have you done any tests on internal resistance?
  17. M

    Meanwell clone- AD488.3-400W power supply mods

    Well, the battery is bottom balanced so will never be balanced at the top.
  18. M

    Meanwell clone- AD488.3-400W power supply mods

    Is there an easy way of terminating the charge when it's finished with the CC phase or at a specific voltage. That's the only problem I have with charging my Lifepo4 pack. During CV phase one or more cells will start overcharging if i'm not babysitting it.
  19. M

    Challenge with brakes

    Yes, that is a lock built into the frame.
  20. M

    Challenge with brakes

    I can't see where :(
  21. M

    Challenge with brakes

    Will any shimano roller brake fit the nuvinci? Do I need any special tools to make them fit together? Also, I will have to do some trickery with the cable routing etc. I suppose?
  22. M

    Challenge with brakes

    Sorry for the late reply. The frame is aluminium. Here is some photos of the dirty bike :lol: As you can see, the frame has already been broken and welded. I want to mount the battery to the frame somewhere in the front, but I am afraid I will make the frame more brittle by drilling into it...
  23. M

    Challenge with brakes

    She is riding on mostly gravel roads and sometimes even on snow. Anyway, I see the rear brake just as much as a backup if the front brake should fail for any reason. There are lots of steep hills around here :shock:
  24. M

    Challenge with brakes

    My mother has a ladies bicycle with a low frame that she loves very much, so last year I converted it to a electric bicycle with a bafang bbs02 mid drive. The big problem is that this bike has a internal geared hub in the back with internal "coasting brake" as in it brakes when you pedal...
  25. M

    Do batteries "waste away" if not used?

    I had the chance to test a couple of unused turnigy 3000mah 3S lipo's today. They were bought in october 2012 and have been stored at the shipping voltage now for 5 years, and in room temperature. Internal resistance is 4-5 mOhm for each cell and capacity is 2969mah for the one I have finished...
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