Hundreds of cycles?

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  • Fluid
    Fast and Furious
    • Apr 2007
    • 8011

    #16
    There may be nothing wrong at all with your cells. There is no science in how you "tested" them, you were comparing apples and oranges. Had you checked the voltage of the Elite cells soon after you bought them - after at least 5 cycles - you may have seen no notable voltage drop. Or you may have. But your "test" is almost worthless. LiPo performance varies from brand to brand, and sometimes within the same brand.



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    Last edited by Fluid; 11-25-2008, 08:28 AM. Reason: typo
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    • motoxbob11
      Senior Member
      • May 2007
      • 190

      #17
      Hi Fluid I did test the Elites when new but I threw away the figures but they are down now for sure compared to then and it really shows on the water or track. The question is longevity and you are the guy who should know. Do you get good cycles into the hundreds with your packs or do they fall off like a Nimh battery? Maybe I just bought the wrong kind.

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      • AntronX
        Senior Member
        • Jul 2008
        • 333

        #18
        How deep did you discharge them? If you took them below 80% depth of discharge (DOD), 50 cycles sounds about right. There is a way you can tell how deep they were cycled. When you put them on charge after having them run your boat, what cumulative mAh did they take to fully recharge? If they took 4600 - 4800 mAh, that should reduce the cycle life pretty bad. What you need, is to set the voltage cutoff on the ESC so the boat stops running at 80% DOD of your lipos, or at 3800 mAh.

        And the dumb question: have you ever cleaned your connectors? I had voltage drop problem with my LiPos once, went away after I cleaned bullet connectors with a cotton swab dipped in Acetone.

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        • motoxbob11
          Senior Member
          • May 2007
          • 190

          #19
          Originally posted by AntronX
          How deep did you discharge them? If you took them below 80% depth of discharge (DOD), 50 cycles sounds about right. There is a way you can tell how deep they were cycled. When you put them on charge after having them run your boat, what cumulative mAh did they take to fully recharge? If they took 4600 - 4800 mAh, that should reduce the cycle life pretty bad. What you need, is to set the voltage cutoff on the ESC so the boat stops running at 80% DOD of your lipos, or at 3800 mAh.

          And the dumb question: have you ever cleaned your connectors? I had voltage drop problem with my LiPos once, went away after I cleaned bullet connectors with a cotton swab dipped in Acetone.
          Thanks thats good to know but I never went that deep into them. replacement mah was usually around 2600 mah. The connectors are clean. The batteries just don't have the same snap to them and I really notice it when I run them in my Associated truck. Oh well I'll keep an eye on my new Enerland battery and see if it stays strong for a long time. Thanks to everyone for the help.

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          • GregS
            Member
            • Apr 2007
            • 82

            #20
            I've had a similar experience with my lipos. I bought a set of Polyrc 4350's and a few months later a set of Polyrc 4900's.

            The 4350's definitely dropped in performance (confirmed with tests) after about 10-15 cycles. I did everything right with them and made no mistakes except for leaving them fully charged for about a month. That's when the performance loss first appeared. It also corresponded to seeing resistance values of twice what they originally were on the charger. I checked the tabs for corrosion and there was none - everything was totally dry. I was also wondering if these batteries really lasted like everyone claims.

            However, they seemed to improve again after a few runs in the boat and the resistance indicated on the charger has also come down significantly.

            The 4900's I made no mistakes with at all and the resistance has creeped up somewhat with them as well. I don't think they're performing quite as well as when new either. I heard somewhere that lipos are most potent the first few cycles and a slight performance loss does occur early on. Not sure of that though.

            Anyway, maybe your's will come back to life somewhat after more runs.

            Greg

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            • motoxbob11
              Senior Member
              • May 2007
              • 190

              #21
              Actually mine might come back to life in "another life" because I tossed them! I have a feeling that nobody has even run one of these batteries hundreds of times. If anyone has let me know what kind they were so I can buy some! Anyway I still love them they are way better than Nimh.

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              • planezero
                Member
                • May 2008
                • 94

                #22
                Are you charging them at 1C max ?
                Higher charge rates are fine, but shorten the useful life span.

                Are you balancing your packs with a balancer ?
                With usage they become out of balance and when you fully charge them (as all cc&cv voltage chargers do) you would be charging one cell more than the other.
                Consequently when you run them you might be discharging the other cell more than you would like.

                HTH

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                • GregS
                  Member
                  • Apr 2007
                  • 82

                  #23
                  I'm not sure if you're asking me the questions or the thread starter but in my case the batteries have always been charged at 1C and have always been perfectly balanced.

                  Greg

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                  • planezero
                    Member
                    • May 2008
                    • 94

                    #24
                    The thread starter....
                    Sounds like a song from The Prodigy

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                    • motoxbob11
                      Senior Member
                      • May 2007
                      • 190

                      #25
                      Yes always at 1C on a Hyperion balance charger. They just wore out is all there is to it. They still charge and discharge but the voltage is down. The boat and truck still run but not as fast.I have a feeling that this is just the way it is. I'm still waiting for someone to say they have hundreds of cycles with no loss (or very little loss) of performance. And like I said if they have I want that brand!

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                      • sjslhill
                        Fast Electric Addict!
                        • Apr 2007
                        • 1513

                        #26
                        100's of cycles with no loss...it's not out there, never has been in any chemistry of f/e racing

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                        • motoxbob11
                          Senior Member
                          • May 2007
                          • 190

                          #27
                          Thank you Mr. Hill you know way more about this than I do. All I know is 300 dollars for three batteries that lasted less than 6 months isn't quite what I had in mind. I just got two Enerland Racing packs and I am going to pay real close attention to how they last!

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                          • sjslhill
                            Fast Electric Addict!
                            • Apr 2007
                            • 1513

                            #28
                            I understand how you feel. The Enerland packs should be among the best, let us know how it works out. Even R/C 2400 nicads would last 100 cycles at most, we tested them in the lab.

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