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  1. J

    Mystery cell possible 15c discharge cells reported on evtv

    You have some of this correct. Apparently the attention span on Endless Fear precludes you watching a 90 minute video so I'll summarize. Actually we ordered 6 100Ah LiFePo4 cells that purport 15C continuous and 20C for up to 10seconds. I'm excited about these and we have yet to receive them...
  2. J

    A123 20Ah cells price down to 17.50$ per cells?

    I don't KNOW they are made in Korea, and I don't know they are NOT made in USA. In fact, the trader insists they ARE made in USA and come from there. I find this extraordinarily unlikely. But it could be so. I was told by someone who should probably know that all the 20Ah cells are actually...
  3. J

    A123 20Ah cells price down to 17.50$ per cells?

    I see ENDLESS FEAR has retained it's nickname very nicely. PAGES of negativity, snarking and sniping from under the bushes. Constant fault finding and negativity. Truly endless fear. The A123 cells appear to be new. They are meeting their design specification sheet. They appear to be in...
  4. J

    Bottom balancing?

    You know, this is so nicely worded and such an excellent summary, that I find myself agreeing almost 100%. Then I stop and review what I know, and have to reverse myself and say, you know, this guy really knows HOW to summarize 100% bullshit into such a palatable form that even knowledgeable...
  5. J

    The most intractable EV engineering issue? State of charge.

    I'm working on something quite similar. What you've found is interesting, but there are a couple of design issues. First, these closed loop sensors require an additional power supply, typically, and in this case both positive and negative 15 vdc. A little DC to DC converter will do it, but...
  6. J

    Bottom balancing?

    Andy, I've heard this so many times I can chant it myself. It goes kinda like this, "Maybe so, but BOY are you going to be SORRY when the Blue Elephant DOES get here. You'll wish then you had bought one of our deluxe Blue Elephant guns then. Right guys? Hey, let's all vote! If enough...
  7. J

    Bottom balancing?

    Criminy. I don't know. We're in the "dark hours" of the Clubman. Tesla was going for max miles, and they got it. I think we're looking at 125-150 real miles on the Clubman, not counting 10-12% regen and not counting 15-20% heat and air conditioning. The difference, is we have a simple...
  8. J

    Bottom balancing?

    I DETEST explosions. They cause me to spill my whiskey, which is annoying. And actually, I like my batteries to be SILENT. ANY noise from them causes me to start looking them over carefully. It's never good. No good news from noisy batteries.... I am actually in AWE of these cells. The...
  9. J

    Bottom balancing?

    I'm starting to see where the problem is here. Lunging at nonsense is not engineering. Sure, I draw 400 amps on the bench. The Speedster, which you draw 70 inferences from inaccurately, routinely draws 540 amps at any freeway speed. And yes, I do have 180Ah cells. That's about 3C. Does that...
  10. J

    Bottom balancing?

    You know, I hadn't thought of it in precisely those terms. Thanks for pointing that out to me Doc. But in answer to your question, I have to say.... YES. I think they are ENTIRELY wrong. They do not use LiFePo4 cells. They use cells with a higher energy density, but that are more dangerous...
  11. J

    Bottom balancing?

    Andy. I'm sure it is. The problem is, I try to judge people not by the color of their signature, but the content of their post. It's kind of a real MLK day type of thing. If you want me to go away so you can preserve your little tin God pecking order and color scheme, I will gladly do so...
  12. J

    Bottom balancing?

    I do understand the way a pack behaves in use. It's what I've been talking about. Monitor for WHAT and WHAT are you going to do with the information. I don't think you guys have been looking at "in use" data. Otherwise the shunting would have never come up, and now the LVC. It's a different...
  13. J

    Bottom balancing?

    I don't know what to tell you pard. I feel your pain. You do NOT understand battery chemistry or maintenance, and it costs money to watch them die. But there is no magic BMS pixie dust to make life simple for you. I wish there were. I am not anti-BMS at all. I just haven't found anything...
  14. J

    Bottom balancing?

    There will be. But it will be less than 5Ah on a 160Ah cell. That's been my point. You seriously extend the life of the cell at the lower voltage, at a very small sacrifice in range, a couple of miles. And you can throw away that $2000 and all that crap in your car representing someones BMS...
  15. J

    Bottom balancing?

    We don't. We never did. We just charged to the higher voltage as a CC/CV charge curve to get the cells fully charged. This is where the conversation started. TS and SE cells fully charged are 3.4v To get there, charge TSE CC/CV at 4.2v. Charge SE CC/CV at 3.6v. In series packs, I use 3.65...
  16. J

    Bottom balancing?

    You don't understand it because it has nothing to do with self discharge. It's just a bleed off of surface charge accumulated during the charging process. The fully charged voltage for these cells is 3.4v - period. It always was. These are larger cells than you are testing, they have a lot...
  17. J

    Bottom balancing?

    IF this is so, then why has no one bothered to produce an Internal Resistance meter for the dashboard? Yes, it indicates a LOT of things. So it is very difficult to determine WHAT it is indicating because you cannot determine easily whether it is damage, temperature, or SOC - in other words...
  18. J

    Bottom balancing?

    My TS cells all fell further to 3.38v with another day of rest, though oddly the damaged TS cell did not. It stayed at 3.41, perhaps a sign of its earlier overcharge adventure. I'm actually capacity testing it now and it is looking very strangely good. I'm about 83 AH out of the cell now at...
  19. J

    Bottom balancing?

    You may live for physics, but you clearly know squat about batteries. Different cells have different charge voltages and headway does not precisely define the genre. TS cells charge to 4.2 v by spec and SE's charge to 3.6. Ri and an ice bath will tell you buttkiss. There isn't any damaged...
  20. J

    Bottom balancing?

    My apologies. I STILL missed it. You ARE using the Yttrium cells? Then we are testing two different chemistries. But how would this explain SE cells. They haven't changed and I DO have the latest of those.... Jack Rickard
  21. J

    Bottom balancing?

    Then we DO have a mystery worth investigating Andy. Because I ran this myself quite manually last night. I would suggest we have TWO possibilities here: 1. Test equipment setup. 2. We're testing two entirely different cell chemistries. When you say "brand new" are you referring to the...
  22. J

    Bottom balancing?

    Ok, then let's dig that monkey wrench back out of the works and get it working again. A123 are NOT the only ones using nano technology. ALL lithium ion cells are based on "nano" technology and most of the work on improving cells have to do with ever finer, more stable, and more complex nano...
  23. J

    Bottom balancing?

    And I would take exception to every point you make here. They do NOT match anything I've learned and are totally wrong. There's no nice way to put that. First, you do NOT stop charging when the first cell in the pack reaches 4v. The charge curve varies depending on the current applied, but a...
  24. J

    Bottom balancing?

    Fair enough. Let's talk about this, but do have a peek at the videos at http://EVTV.me. This is a PERFECT example of a new enthusiast actually in a quandary because of all of this frenzy over BMS. Relax. People are killing cells by worrying them to death with all this theory and equipment...
  25. J

    Bottom balancing?

    Again, I have em. But I really don't have any interest in them. Their ability to hold a "surface charge" has no known application to me. It's just surface charge. No useful energy there. Andy had me going with the comment that you can tell damaged Thundersky cells because they DO descend to...
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