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  1. HANKMARS

    NiMH battery pack mystery

    Agreed. I think it was in Battery University, a statement regarding the charging of parallel NiMH cells as risky because the algorithm of the charging unit can misinterpret the values or more likely won't realize a faulty cell or a cell with a significant charge level difference and will not...
  2. HANKMARS

    NiMH battery pack mystery

    This photo may clarify my statement regarding battery capacity. You are correct in the statement, as a battery is being used to power a circuit, the total amount of available energy is decreasing, the characteristic of battery discharge. Actually this graph shows amount of charge used over time...
  3. HANKMARS

    NiMH battery pack mystery

    Occam's Razor it is. I have a clamp on type meter which includes an Ωs function which, much to my surprise, is quite accurate, apparently. The interconnects of the 6 cell holders consistently read 0.1Ω. The interconnects of the 8 cell holder read 0.5 somewhat consistently. An obvious difference...
  4. HANKMARS

    NiMH battery pack mystery

    I apologize for leaving you stranded, or rather "in the dark" in post #42. This circuit operates by producing a square wave out with a very long time period. Minimum time period of square wave is 3 to 4 seconds. This duration is determined by R4 and adjusted "at the factory" and is constant...
  5. HANKMARS

    Requesting more Greek letters

    As in example:
  6. HANKMARS

    NiMH battery pack mystery

  7. HANKMARS

    NiMH battery pack mystery

    Current space constraints do not allow for 2 - 6 cell packs. An 8 cell holder fits great.
  8. HANKMARS

    NiMH battery pack mystery

    I did send a reply to Alec t in post #30 and post #31. He recommended a test procedure that could very well pin point this problem. I now have 2 projects affected by this problem. One project uses a current of only 0.5 to 2A. The other project needs short bursts of high current to rapidly heat a...
  9. HANKMARS

    NiMH battery pack mystery

    Two "completed" projects where "definition of terms" was of no concern.
  10. HANKMARS

    NiMH battery pack mystery

    Dear Bluejets, I scrolled thru this thread 3 times finding no link sent by you. You mentioned a site name of battery university but "link" and "site name" are not interchangeable terms. Thanks anyway.
  11. HANKMARS

    NiMH battery pack mystery

    This particular thread is specifically concerned with NiMH cells. Are you using the term "capacity" to mean battery capacity as well as % capacity, or do you mean that the amount of energy storage of a cell is affected by its discharge rate?
  12. HANKMARS

    Requesting more Greek letters

    A better suited category. Good move. Thx
  13. HANKMARS

    Requesting more Greek letters

    More specifically, I meant to request that the symbols be placed in the toolbar above the text box in the forums section.
  14. HANKMARS

    Requesting more Greek letters

    May I suggest delta, approximate ( 2 squiggly lines, not 1 ), not equal.
  15. HANKMARS

    NiMH battery pack mystery

    Two 6 cell batteries in series gave me an expected Amax out. ~ 20A. I am leaning towards the idea that the 8 cell holder may be the culprit.
  16. HANKMARS

    NiMH battery pack mystery

    I can do this test at less than Amax, say maybe 1 or 2 amps. May very well give good indication.
  17. HANKMARS

    NiMH battery pack mystery

    This is the direction that my conclusion is headed. This is a difficult or rather involved test. Having only generic VOMs on hand, moving around to the various test points takes way longer then I am willing to short ( 1Ω ) the battery. This would be a definitive test, however. Great idea. I may...
  18. HANKMARS

    NiMH battery pack mystery

    Interesting article. I keep my Amax test as short as possible. Approximately 1 second. Seldom over 2 seconds unless need be. Good idea to have a percentage buffer on charge and discharge ends. Avoid undue stress.
  19. HANKMARS

    NiMH battery pack mystery

    I am not sure I get your point. Output capacity decreases even if discharge rate is constant or even if discharge rate decreases. Any current flow produced by a battery is going to be decreasing available energy. The battery is discharging any time that it is in use. The available energy is...
  20. HANKMARS

    NiMH battery pack mystery

    BIC lighter, a single 1Ω 100W resistor, 2 - 1Ω 100W resistors in series, a 6 x AA battery holder, an 8 x AA battery holder, and 4 big honkin - 0.39Ω resistors just for fun.
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