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BC20-4 (DJI) charger vs the Thunder AC680

Discussion in 'Phantom FC40 Discussion' started by mendocinotim, Sep 11, 2014.

  1. mendocinotim

    Sep 11, 2014
    Likes Received:
    Over the past few months I have been struggling to understand why (identical) test flights are lasting only 5-12 minutes (ave times overall are around 8 min) - with 8 separate tests used in this sample.

    I have a non-standard FC40, which I modified to use two externally mounted MadDog 11.1v 2700mAh 25C batteries, where I upgraded the props to the Phantom 2's (9") props, and I also installed a Walkera G-2D gimble.

    All tests have been done using dual batteries.

    I have two different balance-chargers.
    One that that came with the FC40 (the BC20-4).
    The other is a Thunder AC680 balance charger.

    Batteries are charged with the following settings..
    Batteries charged on the Thunder charger are charged at 1.3A - typical charge time: <30min in a balanced charge.
    Batteries charged with DJI's BC20-4 charger are charged at 2A - typical (balanced) charge time: about 1 1/2 hrs.
    Using this method, I get an average of 8 min flight.

    NOTE: all flights are done by hovering the phantom at about 10ft, and holding that position until it self-lands.
    ALSO NOTE: that the Phantom is set to factory specs for all these tests.

    I'm posting this because it turns out I can get more flight time - averaging 18 min 20 sec - simply by charging both batteries used in a test with the DJI charger. But I found the Thunder charger (if used on one of the two batteries in a test) will fly for only half as long.
    I now know why flight durations were so short.

    Has anyone else compared these two chargers side-by-side?
    Has anyone else seen similar results?

    The Thunder charger is well liked in the RC community; that's why I got it in the first place; but these results have convinced me that the Thunder charger produces shorter flight times than DJI's charger. Yes, the DJI charger takes nearly three times as long to complete a balancing charge (and that is not so good), but for twice the flight time 'it is well worth the wait.