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Battery Discharging

Discussion in 'Pro/Adv Discussion' started by Waylander, Jan 28, 2016.

  1. Waylander

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    Hi guys
    I know a lot has been said about battery discharging, in the copter, auto discharge etc, is there any reason why the batteries can not be discharged on the bench via a dummy load
    Waylander
     
  2. msinger

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    There are some 3rd party battery dischargers available. I own this one. If you're not a fan of hot bulbs, there is also a version that runs a fan to discharge the battery.
     
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  3. robinb

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    I use a car halogen light bulb with a set of flying leads i plug into the terminals, switch it on and watch power go down.

    Keep bulb well away from anything inflammable at same time monitor the led indicators on the back .
     
  4. msinger

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    Please post a photo of your setup.
     
  5. robinb

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    Not near kit at present, but its a light bulb, 2 wires with spade terminals on.

    Not at all high tech but its effective and works well.
     
  6. msinger

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    No problem. Maybe later? I thought it would be interesting to see -- in case anyone else wants to make one.
     
  7. snowghost

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    Great tip. I ordered the bulb one. Now it won't be a pain to do a full discharge.
     
  8. Pete Leare

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    @msinger, how do you know when you're down to 8% using this discharger?

    Never mind I found the answer on Amazon. Just ordered one also!
     
  9. Waylander

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    Hi msinger
    Do you know if the discharge rate needs to be constant, or variable, in the copter with the motors running without props I would guess that the discharge rate is constant, so my thoughts are that connecting a High wattage wire wound resistor with an ohmic value giving a discharge rate of around 1.6 amps would not do the battery any harm, and unlike a tungsten halogen lamp it would not get so hot.
    Any thoughts comments....?
    Waylander
     
  10. msinger

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    DJI does not mention this anywhere, so I'm assuming it does not matter. Constant is definitely not the only option though since DJI often recommends flying the Phantom to discharge the battery. And, when you're flying, the battery cells levels are most certainly not constant.
     
  11. CactusJackSlade

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  12. With The Birds

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    At 1.6A you are looking at well over two hours to bring a full pack down.

    Lets say on average you get 15 mins landing at 30
    At 1.6 amps your looking at over two hours to bring a full pack down.

    Lets say you get 15mins in the air out of a full pack landing around 30%. For a healthy pack thats around 13A average load. That should give you a starting point for what is safe in calculating your dummy load.
     
  13. Numone

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    HeY Mike,
    The discharger with the bulb states its for the P2 battery. Can you cfm it works with the P3 battery too?
    Cheers... Rob
     
  14. msinger

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    It works. I own one.

    The important part of the description is "Battery Discharger for 3-6S". The P3 battery is a 4S battery. The Inspire 1 is a 6S.
     
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  15. Numone

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    Cheers Mike. Found the same one on eBay UK for $11.69 shipped in the UK. Says its for the P2 but, like yours, it has 3-6S on the board! Delighted and wouldn't have found it without you, so thanks once again Mike!
    Cheers... Rob
     
  16. Mark The Droner

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    That's the same one I have. I'm one of the reviewers. Works great for my P2V.
     
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  17. generaltso

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    I just tried out the bulb discharger for the first time. Wow, is it bright! I was seeing spots for several minutes afterward. After the discharge finished, I noticed one side of the connector that holds the bulb is burnt and melted. I can't imagine this is normal?
     
  18. Mark The Droner

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    Nope, that's not normal.
     
  19. generaltso

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    I figured as much. This thing gets so ridiculously hot.

    Has anyone tried the one with the fan? It looks like it's basically just a box with USB ports, so I guess you could plug anything into it (like an iPad). But I can't tell if it really has any intelligence built in like the bulb one does. Will it stop discharging when storage voltage is reached? Can it do a deep discharge? How long does it take?

    Amazon.com: "SUMOMOTO" Interlligent Battery Discharging Discharger for DJI Phantom 3 2 Inspire 1 3S 4S 6S Battery: Toys & Games
     
  20. Mark The Droner

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    The device could have been designed better so that the bulb can be safely set down without such a high risk of burning something. I like to lay mine over a coffee cup and pinch it with a small clamp (like a clothes pin) to stabilize it.

    Also, the instructions are horrible.

    The board is smart. If you have a full battery, you start the discharger and it will beep once and then it will discharge it to a optimim storage level and then turn off. At that point if you press the tiny button on the board, it will beep twice indicating deep discharge mode and it'll bring the battery down to a deep discharge. I don't know what it does to a P3 battery but on mine it brings it all the way down to 3%.

    Here's a video on how to do it.

    After the deep discharge, don't forget to give your battery a full charge immediately.