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Anybody know anything about the Fullriver lifepo4 single cells 26650, etc.

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  • #16
    Originally posted by VicRC View Post
    Currently just flying quad racers and the packs are mostly 4s 1500mah but at 75C rating, amazing how much power you can get from them of course a 2-3 minute of flight time is really quick.
    Now that is some funny stuff, I do not care who you are.

    Don't get your shorts in knot, I am not making fun of you. But a 75C battery is impossible, and is pure marketing genius. You pay an extremely high premium having 75C printed on that battery. You are being ripped off.

    If you want to know the True C-Rate of a RC LiPo battery, you can measure it if you have a charger that reads the individual cell Internal Resistance. If you have one you are in for a Hell of a Shock.

    Here is how you do it. I will use your battery as an example.

    1. 6 watts x mah / 1000 = 6 x 1500 / 1000 = 9 watts. All you are doing here is finding a thermal mass limit of your cell of 6 watts per Amp Hour of a individual cell. You have a 1.5 AH cell x 6 watts is 9 watts.

    2. Now is simple Ohm's Law. Use the highest Resistance cell of your 4 cells. If your battery is in excellent shape and new will bee roughly .006 Ohms or 6 milli-ohms. Once you have that you find the maximum current your cell can safely dissipate using Ohm's Law of the Square Root of Power / Resistance. So ^2 of 9 watts / .006 Ohms = 38.7 Amps.

    3. Now you find the True C-Rate for your battery and you will not be happy. C-Rate = Max Amps / mah x 1000 = 38.7 / 1500 x 1000 = 25.8C. Far from 5C you paid for..

    I have only been in the hobby now for about 4 years. But after working with batteries for 40 years I knew C-Rates were complete fantasy. Every manufacture lies big time. It took me a while to find engineers that make LiPo's for RC and they gave me the Formula I just shared with you. That formula of 6 watts for every AH is ridiculous. If you were to actually run your battery at 38 amps means the battery is burning 9 watts x 4 cells = 36 watts smoking hot.

    There is also a web site with a data base from users measuring Real C-Rates. No on the face of the earth has ever measured one greater than 30C. 75C is impossible. I run 25C cells and most are around 18 to 20 C. I do have some rated 45/90C Turnigh Nano's but their real C-Rate is 23 to 26 brand new.

    Here is something else to consider. I bet if you measure the Internal Resistance of your cell they will be roughly .007 Ohms or 20C. 20C on a 1500 mah battery is 30 amps. That means each cell looses .3 volts per cell or 1.2 volts for a 4S pack. Again you can do the math 1.2 volts x 30 amps = 36 watts of hear cooking your battery. That is why the puff up.

    Give you a hint. Buy a Gens Ace or Thunder Power 4S 1500 mah 25C battery will perform just as good as your 75C battery and only cost half as much.
    Last edited by Sunking; 04-22-2017, 01:27 PM.
    MSEE, PE

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    • #17
      Originally posted by VicRC View Post
      I try and not charge LiPo at home if I do it is inside my metal charging cabinet. Currently just flying quad racers and the packs are mostly 4s 1500mah but at 75C rating, amazing how much power you can get from them of course a 2-3 minute of flight time is really quick.

      I wont hijack this thread any longer and will start a new one. I hope to get a lot of help from the experts here.
      Vic. You remind me of someone I know outside of this Forum. I currently live in the Clearwater area of Florida. Is that any where close to where you live?

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      • #18
        Sunking thanks for the insights on LiPo C ratings . I don't even know how they come up with lipo rating, I only use it as reference. Maybe they label them like how the power feels... gee It feels like 50 percent better and it can hold full power 50 percent more times so I am going to label them 2x.....hmmm 40c battery is now 80C ... lol.

        Anyways all my packs are the GenAce Tattu 75C, disregard the 75C, anyways all I care about is it provides the most power and hopefully withstand my punishment of 40-50 flights. Nothing like a fresh brand new LiPo cuz the next flight on it appears to be always less.
        Last edited by VicRC; 04-22-2017, 07:10 PM.

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        • #19
          Originally posted by VicRC View Post
          Sunking thanks for the insights on LiPo C ratings . I don't even know how they come up with lipo rating, I only use it as reference. Maybe they label them like how the power feels... gee It feels like 50 percent better and it can hold full power 50 percent more times so I am going to label them 2x.....hmmm 40c battery is now 80C ... lol.

          Anyways all my packs are the GenAce Tattu 75C, disregard the 75C, anyways all I care about is it provides the most power and hopefully withstand my punishment of 40-50 flights. Nothing like a fresh brand new LiPo cuz the next flight on it appears to be always less.
          VIC unfortunately the whole C-Rating is just a crime and an arbitrary number marketers come up setting with Engineers of how much heat they think the battery can tolerate before it blows up. It revolves arounds 6 watts per AH of battery which is ridiculous amount of heat. When you stop and do some math you begin to realize it is pure BS and you are getting robbed. Allow me to you a simple question.

          What is your Flight Time?

          If you say 10 minutes says you need 6C continuous, and 12 C burst.
          If you say 5 minutes means you need 12 C continuous, and 24C burst

          The only way you can justify 75 C is less than 48 seconds fly time. If your RC Charger can measure Internal Resistance do some experiments. Then go plug you numbers into [B][I][U]this calculator[/U][/I][/B] and see what the C-Rate really is. I have measured many LiPo's and hundreds of people have done the same. No one has ever measured one more than 30C. I bet you a dollar if you used a Gens Ace 4S 1500 mah 25C battery would perform just as good as your twice as expensive 75C battery.

          In order for your 1500 mah cell to be 75C the Internal Resistance would have to be .0005 Ohms. Impossible for that small of a battery. Not even 100 AH cells go that low. Most likely you will measure as low a .004 and up to .01 Ohms and find out you have 25C to 18C battery.
          Last edited by Sunking; 04-22-2017, 07:56 PM.
          MSEE, PE

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          • #20
            Originally posted by SunEagle View Post

            Vic. You remind me of someone I know outside of this Forum. I currently live in the Clearwater area of Florida. Is that any where close to where you live?
            I am in Burbank, Ca. It gets super hot sometimes. We have our own POCO here and they charge $0.1672 kWh at Tier2 , I am averaging around 28k per day.

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            • #21
              Originally posted by Sunking View Post


              What is your Flight Time?

              If you say 10 minutes says you need 6C continuous, and 12 C burst.
              If you say 5 minutes means you need 12 C continuous, and 24C burst

              I can do 5 minute but that would require 1/4 throttle throughout the entire flight, not much fun with that. 10 min is not possible.

              I fly less than 3 mintues consuming around around 1000-1200 from 1500ma 4s pack. I do have a charger that displays battery resistance, will pay attention next time I charge.

              Thanks for the great info and your time for educating me on LiPo technology

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              • #22
                Originally posted by VicRC View Post

                I am in Burbank, Ca. It gets super hot sometimes. We have our own POCO here and they charge $0.1672 kWh at Tier2 , I am averaging around 28k per day.
                Thanks for getting back to me. I just happen to know someone that lives close to me that fly's RC planes and is named Vic.

                We get hot here in Fl in the summer. At least I only have to pay about $0.10/kWh up to 1000kWh and then about $0.12/kWh for anything above that first 1000.

                We finally got our consumption below 40kWh a day which costs us about $4.75 or $143/mth on average (including all taxes and fees), but it has been a fight to keep other family members from leaving the lights and fans on all the time.

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                • #23
                  Originally posted by LETitROLL View Post
                  Just looking to play around with some lifepo4 cells, dont want to spend much money so i know i will be dealing with lesser quality batts, just want to make sure they are indeed lifepo4 and not some counterfit other chemistry pretending to be lifepo4. I pump some water up from a spring at my cabin (not very often) and currently using a used car battery that is working fine to run the shurflo 12v pump, but the battery is tired (10 years old) and gets heavy on the 600' long, steep trail packing it down and back to recharge, the pump draws close to 5a for this particular lift, and i run it about 30 minutes maybe 3 or 4 times per week when i am around there. I see some cheap 26650 5500mah 3.2v supposed lifepo4 cells i can get for 3 bucks each in bulk, just wondering what pitfalls i would be looking at to run 2p4s pack for 12v 10ah which should be super light to pack and i think could do okay with a .5C draw for 20-30 mins. I have a Victron 75/15 with cable and software to set the current limit and voltages proper just not sure if there is anything to look out for with those particular batts or the 2p arrangement.
                  LETitROLL, here is a small pack I built using 32650 LiFePo4 5500 cells, a 4s1P pack for powering my small portable air pump. A TPU printed shell protects the pack, notice I have a balance plug just in case I want to read the voltages of each cell and balance charge the pack when needed. I also built a 4s5p pack, at 12.8V 27.5A weighing in at 8lbs is the largest I built from LiFePo4s, which I am using as a power supply from my field chargers.

                  Nothing stopping you from tinkering, just be safe!
                  Attached Files

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                  • #24
                    Originally posted by VicRC View Post
                    I fly less than 3 mintues consuming around around 1000-1200 from 1500ma 4s pack. I do have a charger that displays battery resistance, will pay attention next time I charge.

                    Thanks for the great info and your time for educating me on LiPo technology
                    You are welcome. Save yourself some significant battery dollars. At 3 minutes is roughly C25. Any more is just a waste of money and added weight. Gens Ace 25C are great batteries. I have a ton 3S 2200 mah 25C. Paid $11 for each.

                    Good luck

                    MSEE, PE

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