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Don't forget about those batteries!

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  • #21
    I have my LVCs set to cut off at 3.7 to 3.8 v/cell at full throttle. The packs are rarely below 3.6 when I pull them from the aircraft. Its a reasonable storage level.

    If I run them down due to charging more packs than needed, I do it at full throttle. That will trigger the LVC by 3.7 v/cell. (and its faster than the lower throttle method)


    ************

    You need to worry about battery temperature somewhat...

    Best current delivery temp for LiPos is 120 to 130 F. You can severely damage the packs if above 140 F. You are reducing the battery life (charge cycles) at 120 F.

    When flying in 105 to 110 F ambient air, its hard to keep the packs below 120 F in anything other than a lazy trainer. Get them out and maximize cooling ASAP. (in the shade with good airflow around the packs, you don't really need to use a fan, but it helps)

    DO NOT RECHARGE A HOT PACK Let it cool first.

    Most modern ESCs have a thermal shutdown where they cut power to the motor if they get too hot. Some of the earlier ones with thermal shutdown also killed the BEC power... There might still be some made today which will do that. There are also still some without any thermal shutdown, so its a good idea to read about your ESC specs.
    FF gliders and rubber power since 1966, CL 1970-1990, RC since 1975.

    current planes from 1/2 oz to 22 lbs

    Comment


    • #22
      Originally posted by fhhuber View Post
      I have my LVCs set to cut off at 3.7 to 3.8 v/cell at full throttle. The packs are rarely below 3.6 when I pull them from the aircraft. Its a reasonable storage level.

      If I run them down due to charging more packs than needed, I do it at full throttle. That will trigger the LVC by 3.7 v/cell. (and its faster than the lower throttle method)


      ************

      You need to worry about battery temperature somewhat...

      Best current delivery temp for LiPos is 120 to 130 F. You can severely damage the packs if above 140 F. You are reducing the battery life (charge cycles) at 120 F.

      When flying in 105 to 110 F ambient air, its hard to keep the packs below 120 F in anything other than a lazy trainer. Get them out and maximize cooling ASAP. (in the shade with good airflow around the packs, you don't really need to use a fan, but it helps)

      DO NOT RECHARGE A HOT PACK Let it cool first.

      Most modern ESCs have a thermal shutdown where they cut power to the motor if they get too hot. Some of the earlier ones with thermal shutdown also killed the BEC power... There might still be some made today which will do that. There are also still some without any thermal shutdown, so its a good idea to read about your ESC specs.
      fhhuber, Thank you, I appreciate the 'good news'. All then seemed normal, running storage charges now. These LIPOs are most certainly a different animal when compared to NiCads. Best to you, LB
      I solemnly swear to "over-celebrate" the smallest of victories.
      ~Lucky B*st*rd~

      You'll never be good at something unless you're willing to suck at it first.
      ~Anonymous~

      AMA#116446

      Comment


      • #23
        Never store full charged packs in a car that will get hot in the summer sun.
        One of the fastest ways to puff a pack is to get it really hot while fully charged.

        (Gets hot enough here to bake cookies on the dashboard)
        FF gliders and rubber power since 1966, CL 1970-1990, RC since 1975.

        current planes from 1/2 oz to 22 lbs

        Comment


        • #24
          This is why I never leave my LIPO's alone while charging!

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          • #25
            That wasn't a lipo fire.
            AMA 424553

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            • #26
              Originally posted by RRHandy View Post
              That wasn't a lipo fire.
              Don't those things use LiFe batteries for their RXs? That looked more like a Nitro fire.

              Comment


              • #27
                Originally posted by xviper View Post
                Don't those things use LiFe batteries for their RXs? That looked more like a Nitro fire.
                Gasoline.
                Looks like a fuel leak that met an ignition source.

                You'd have a hard time seeing a glow fuel fire. Alcohol fires (and Ntromethane) burn with a flame that is practically invisible in daylight.
                FF gliders and rubber power since 1966, CL 1970-1990, RC since 1975.

                current planes from 1/2 oz to 22 lbs

                Comment


                • #28
                  Originally posted by RRHandy View Post
                  That wasn't a lipo fire.
                  . Yes Ron, it was a LIPO fire. I was standing right next to the plane while he was charging his LIPO batteries getting ready for his next flight. The bottom right corner of the second picture shows what's left of the batteries after he pulled them out.

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                  • #29
                    Color of flame says gasoline got involved... but it looks like fuel lines melted/burned through which could have been caused by LiPo burning.

                    ****************

                    Hitec HV servos can use 2S LiPo direct with no regulator and most Spektrum RXs can handle it too (3.85v to 9.0v operating range. Lower will "brown out", Higher will burn up). Some of the people flying larger models are now powering their radio systems with 2S LiPo.
                    (I have one such model under construction, doesn't really need the HV, but I got the servos in a used model I bought.)

                    Some of the gas engine ignitions want 5.0v regulated, some will operate fine from 4.5v to 6.0v (4 cell NiCd) or 6.0v to 7.0v (2S LiFe) and some want 2S LiPo... and there are probably others that I haven't seen yet.
                    FF gliders and rubber power since 1966, CL 1970-1990, RC since 1975.

                    current planes from 1/2 oz to 22 lbs

                    Comment


                    • #30
                      Lipo fire and $40,000 worth of damage. An experienced IMAC piolet here was charging batteries in his trailer. Ran in the house for a minute and heard a muffled pop. A few minutes later the neighbors were beating on the front door yelling "Fire". The two batteries being charged exploded, burnt the trailer to the ground, burnt the rear end of the F250 and the side of his motorhome. Three IMAC planes ($3 to $5,000) and lots of support equipment. It was all parked on top of artificial turf ($4,000). The fire department was minutes away and it took their efforts to get the fire out. This all got my attention and all of my batteries are now in lipo bags and I'm present for every charge. Hard lesson learned

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                      • #31
                        Be interesting to find out what item/conditions caused the fire.

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