Lipo info

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  • greenman407
    Admiral
    • Feb 2009
    • 7530

    #1

    Lipo info

    Im learning more and more about Lipos as I go. Just thought that I would share a tid bit with you. The Lipo battery manufacturers are saying that for maximum life you should balance charge your batterys but when you are done running you should store them in a cool dry place at what they call "Storage Voltage". And that would be 3.85 volts per cell. Just a little FYI.
    IT TAKES GREAT INTELLIGENCE TO FAKE SUCH STUPIDITY!
  • greenman407
    Admiral
    • Feb 2009
    • 7530

    #2
    Even with using Lipo guards, your liable to find that you are below the recommended storage voltage, especially in high drain hobbys. So, its recommended that you charge them back up and stop at 3.85 volts. Kind of a pain but some of these batterys are over $100 each easy. Depends on the deal you happen to get.
    IT TAKES GREAT INTELLIGENCE TO FAKE SUCH STUPIDITY!

    Comment

    • KevinMc
      Commander
      • Feb 2009
      • 305

      #3
      Hi Mark,

      I agree completely that proper LiPo maintenance will extend LiPo life - even with a LiPo Guard. LiPo guard will warn you when the battery is "empty" (3.0V/cell under load), but that's a different thing from discharging to the storage level.

      Another thing to keep in mind is that you shouldn't store your LiPos fully charged as this will also shorten their life. If you don't use 'em when you go out to run, bleed them down to the storage charge level before you put them away for the week.
      Kevin McLeod - Oscar II driver
      KMc Designs

      Comment

      • greenman407
        Admiral
        • Feb 2009
        • 7530

        #4
        Yes, I think that has been one of the reasons for the early demise of some of mine. Problem is that I dont have a way to bleed them down. Maybe I could make something.
        IT TAKES GREAT INTELLIGENCE TO FAKE SUCH STUPIDITY!

        Comment

        • vital.spark
          Commander

          • May 2010
          • 304

          #5
          The charger I use actually has a storage setting.

          Comment

          • Subculture
            Admiral

            • Feb 2009
            • 2414

            #6
            One of the things that will really extend the life of lipo batteries is not to run them down too low. Really 3 volts per cell is maximum. The quadcopter boys run their batteries to 3.7 volts per cell (I believe that is off load), by that stage the batteries are 80% empty (or 20% full if you're an optimist). Obviously with a pure thrust machine you don't want to run out of juice when in mid air, or it's a case of SPLAT!

            Perhaps the lipo checker could be adapted to include a higher cut-off.

            I always balance charge lipos, unless they're single cell packs off course!

            Comment

            • greenman407
              Admiral
              • Feb 2009
              • 7530

              #7
              Heres the charger I picked up about a year ago. Economical and works real well. A couple of features that I would have liked to see is discharge and storage charge settings.Click image for larger version

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              IT TAKES GREAT INTELLIGENCE TO FAKE SUCH STUPIDITY!

              Comment

              • greenman407
                Admiral
                • Feb 2009
                • 7530

                #8
                I am making my own Lipo dis-charger. I bought a piece of angle from Lowes and attached five(5) 540 electric motors to it and wired it up to plug into a battery. On the one on the end I attached a small 7" airplane propeller to put some load on things and drain more quickly and provide some cooling. While the battery is discharging I monitor the battery using a Lipo volt meter plugged into the Balancing plug.
                I also ordered another charger that has a discharge feature to it. Pictures soon.
                IT TAKES GREAT INTELLIGENCE TO FAKE SUCH STUPIDITY!

                Comment

                • Subculture
                  Admiral

                  • Feb 2009
                  • 2414

                  #9
                  Why are you decharging lipos?

                  Comment

                  • greenman407
                    Admiral
                    • Feb 2009
                    • 7530

                    #10
                    Because sometimes you charge up a pack and then your plans change and you can not use the pack, so you have to store it at full charge. Not Good, according to the Lipo manufacturers. So you discharge the pack down to the recommended storage voltage of 3.85 volts per cell. I have gone thru at least 3 Lipo packs after getting very little service out of them. It has been suggested to me by many that its because I stored them at full charge.
                    Last edited by greenman407; 06-23-2014, 05:07 PM.
                    IT TAKES GREAT INTELLIGENCE TO FAKE SUCH STUPIDITY!

                    Comment

                    • greenman407
                      Admiral
                      • Feb 2009
                      • 7530

                      #11
                      So, here it is. Unconventional.........abomination.......hodgepodg e.......can you think of anymore tags? Anyway, it works. And its aircooled to boot. Puts off quite a blast, especially on 11.1 volts 3s.Click image for larger version

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                      Last edited by greenman407; 06-23-2014, 06:32 PM.
                      IT TAKES GREAT INTELLIGENCE TO FAKE SUCH STUPIDITY!

                      Comment

                      • greenman407
                        Admiral
                        • Feb 2009
                        • 7530

                        #12
                        I have a couple of 3s 6400 Mah "Onyx" Lipo batterys. Not cheap, cheap, but not outrageous either. About $80 each. Well, they are rated at 25c. Ive been using them for Submarine duty and they work great for that. However, I tried them on my Brushless Blackjack 29 and they moved it along well but, they got a little hot(140 degrees). One of them swelled up a little bit, but returned to normal when it cooled. So I ordered some 35c for that application, about $110 each. Well, anyway back to the 25c ones. My charger has a variable charge setting where I usually select 5 amps. On the 35c and 40 c that I have the machine , therefore charges at 5.0 amps. The 25c however, it wont charge that high. You set it at 5 amps and with these batterys it will only charge 3.8 amps. Im thinking that the charger selects the Max charge rate that it detects that the packs will handle. They must have a higher internal resistance. Hold that thought while I go get a volt ohm meter and see what difference that I can detect between the two types.
                        IT TAKES GREAT INTELLIGENCE TO FAKE SUCH STUPIDITY!

                        Comment

                        • greenman407
                          Admiral
                          • Feb 2009
                          • 7530

                          #13
                          The VOM shows a lower resistance for the 25c than for the 35 or 40c. I dont know.
                          IT TAKES GREAT INTELLIGENCE TO FAKE SUCH STUPIDITY!

                          Comment

                          • Subculture
                            Admiral

                            • Feb 2009
                            • 2414

                            #14
                            Storage voltage is really for long term. e.g. months rather than days.

                            Comment

                            • greenman407
                              Admiral
                              • Feb 2009
                              • 7530

                              #15
                              Yep and that sounds like me. If I dont go ahead and get it drained down right then and there, Ill forget and move onto another project, get distracted, you know the routine. Another thing that they say hurts these things is temperature, not just because of rapid discharge but storage temperature. My storage shed will get up to probably 110 degrees in the summer. Best not to store them there. I store mine in the house in a metal tool box. If something were to happen ....at least its in a steel tool box. I used to have a fire proof safe, that was the best.
                              Last edited by greenman407; 06-25-2014, 06:31 PM.
                              IT TAKES GREAT INTELLIGENCE TO FAKE SUCH STUPIDITY!

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