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Is it OK to hover drain the batteries in the garden?

Discussion in 'General Discussion' started by TheSaffer, May 15, 2016.

  1. TheSaffer

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    Location:
    Buckhurst Hill, Essex
    I have a fairly big rear garden and I would like to know if its OK to drain the batteries by hovering really low?
    The reason for the question being that my neighbors are within 30m.

    I'm not that keen on flying indoors to drain the batteries.

    ?
     
  2. Phatzo

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    its your garden, isn't it... you can do what you want on and in it. no?
    if you are good friend with your neighbor then talk with hin if the noise is ok with him. but if you want to drain the batt just send her up 30-40 m and the everybody hears the lady buzz :)
    i used to do the same thing. big a** garden and i just go out in the far back to fiddle around with the bird (sounds weird now) :D


    Sent from my iPhone using Tapatalk
     
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  3. lake_flyer

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    You will not be insured if the bird causes any trouble. 50m is the minimum distance you should keep your bird from the neighbours house, or 150 if it is a congested area. In the Netherlands, that is. But I thought UK was the same.
     
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  4. Phatzo

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    wow. hungary is then really far far behind making ANY regulations at current...


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  5. Alastair

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    Here's a link to what I use. It will discharge to 50% for storage or down to 5% for recycling. Saves putting unnecessary time on expensive motors. There's also different versions available since I bought mine.

    TMS Battery Discharger 3-6S 12V Light Bulb For DJI Phantom 2/3 Inspire 1
     
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  6. Airborne visuals

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    As long as it's take off or landing then the limit is only 30M

    It's still a good idea to speak to the neighbour and explain that you are only going to be hovering a couple of feet off the ground and not pointing the camera at them and spying on them in the garden.

    This is all assuming you are not in a congested area.
     
  7. DavidB

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    I find it interesting that many pilots run down the batteries by simply hovering. My strategy, if I end the day with one or more fully charged batteries, is to use the the lights as suggested by Alistair. I have 2 (for the cost of postage to Australia compared to the cost of such an item - I often get "a spare"). I am happy to try and use up all the batteries by practice flying in the field BUT what benefit is there in hovering? Wear and tear on the motors etc. for no benefit at all. I don't understand it! o_O
     
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  8. McT

    McT

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    Does anyone know if these or something similar are available in the UK ?
     
  9. Batteryman1952

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    Please explain why you want to discharge your battery? Is this some sort of safety precaution? This will only shorten the life of your battery!
     
  10. Alastair

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    There's lots of info in the forum on this but basically if you're batteries are at 100% and you don't use them, after 10 days they will automatically discharge for storage. There have been issues in the past with letting this happen, so if you're not going to use the batteries for a period of time, you should discharge to 50% to prevent it from automatically discharging.

    Occasionally, some firmware updates require you to discharge the batteries below 5% to "recycle". Also every 10 to 15 charges, you should recycle.

    You are correct about reducing the lifespan of the battery with all the discharging however, with the hardware that's contained within, it's a necessary evil.
     
  11. Steven Jurick

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    1) Hovering low allows for possibilities of introducing debris into your motors

    2) If you are going to bother getting in the air to run the batts down, why not take the opportunity to get some footage?
     
  12. Ralph thompson

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    Safer, I do exactly this. Find a cleanish clear space and hover at 10' for as long as it takes to get to 10% battery power. Be careful it doesnt trigger RTH if your home position is near any obstacles. All the bells & whistles will be screaming at u at 10% so land and let it run 'til it shuts down, I think that is around 5%. Switch off the battery and remove. Let the battery cool down ( this takes a few hrs) but then immediately recharge fully (don't leave it at 5%). I've done this many times, works well. Good battery maintenance is really important. I'm just waiting for a custom built discharging device which I think is the right way to go.
     
  13. The Editor

    The Editor Moderator
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    Try One of these.
     
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  14. Ralph thompson

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    Yes thanks Ed., that's the one I've purchased but it takes a month or so for delivery. (I thing someone in this forum recommended it to me a while ago).
    I did send a request to DJI for their recommendations but also suggested that in view of the importance of battery maintenance, that they make a version of their multi charger that also discharges. They have not responded. Seems weird to me that they don't offer this. Bigger fish to fry I guess.
     
  15. RaptorMan

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    This is another topic that has opinions that are all over the map. I believe E suggests you need to bring the cell voltage down to 3.3VDC or about 3% and at that point the battery automatically shuts down. So, hovering isn't going to get you down, safely, to 3% so it makes sense to use another method.

    I'm looking at the idea of using a 24VDC/115VAC inverter to brain the battery and to provide usable power for lighting etc. Perhaps run the TV or some lights to drain the battery to cutoff in, say, 5 hours from full and less from a lower state of charge. The idea of wasting energy is anathema to me.

    But, if using the energy from the battery isn't right for you then draining with light bulbs make more sense -- when the voltage is at 3.3VDC/cell or about 3% the pack controller will automatically shut the pack down so there should be no worries about draining below the minimum...

    E, could you chime in here?


    Brian
     
  16. The Editor

    The Editor Moderator
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    Please see my post #19 and 21 HERE which hopefully make things a bit clearer.
     
  17. Ralph thompson

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    Yes I read his post, I will try this, he sounds more knowledgeable than I. Healthy Drones is good to check the battery cell's and I'm a little concerned as I monitor cell voltage and variation to see they do vary a lot. Everytime I launch, I hover at 5 ft and first check the batteries (in Canadian winters, you need to check your battery temp is above 15 deg C) but I have observed the different voltages. I thin Raptorman should write a Paper on battery maintenance, DJI don't do such a great job on this.
    BTW I did try using an old Shutterhawk Supercharger (my own adapted connectors) to discharge a couple of my Inspire 1 Pro batteries but not being so knowledgeable, wasnt quite sure how far to let it discharge. The manual says to discharge to just above the Spec. voltage (no lower) but then I thought about the individual cells and got nervous. Complicated subject and mistakes can be costly.
     
  18. The Editor

    The Editor Moderator
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    Guys, in the absence of having any device/gadget that will discharge your packs, it is perfectly acceptable to hover the Inspire until the battery turns off.
    Just make sure you cancel any RTH messages when they occur and at the critical battery level you will need to keep pushing up on the throttle stick to prevent the auto land from bringing the aircraft down to the ground.
    At the critical battery level it is wise to bring the Inspire down to around 6" off the ground (and best over some longer grass and obviously with the landing gear down!)
    Just stay at this very low level until the battery shuts down and your Inspire will drop onto the longer grass and will be fine.
    What you may well find is that you battery percentage display shows 0% but your Inspire still actually flies for a minute or maybe more. This is a good indication that your battery was out of calibration!
     
  19. RaptorMan

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    Thanks E, I have read this in the past and I'm now at the point where I need to start doing the pack cycling. The light bulb method is no doubt the cheapest solution and since the controller in the battery will automatically shut off at 3.3VDC/cell this method achieves the drain requirement without risking pack damage. I would think, however, that a less than 1C rate would be preferred to get to the lower voltage. OTH, having a drain rate that's closer to the actual drain in flight might make for a more accurate calibration.

    By my estimate the average drain in flight is about 450W (i1 Pro) but I don't think you want to drain for storage or calibration at that rate as the higher the current the battery is subject to the shorter its lifespan. So, maybe 150W is about the right balance -- fast enough to more closely match the actual drain profile in flight but slow enough to limit the degradation of the pack due to high current.


    Brian
     
    #19 RaptorMan, May 21, 2016
    Last edited: May 22, 2016
  20. Yellow Fellow

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    Could someone who is wiser than me clarify best practice?

    What I tend to do with my (TB47) batteries is as follows:

    1. After use, I fully charge them to 100% and then allow them to do an auto discharge over 3 days. This, I believe, takes them down to the 'safe' storage level of around 60%.

    2. Recharge to 100% before use (obviously).

    3. Every 20 or so charging cycles, completely discharge and then recharge to 100%.

    However, on the Phantom Angel web site that The Editor kindly pointed to, it says: "Manufacturers (including DJI) state that LiPo batteries should be stored at ~50% charge if left for more than 24 hours. DJI’s auto-discharge function takes at least 3 days to discharge - that’s not good enough."

    So, am I doing the wrong thing in recharging after use and allowing my batts to auto-discharge? Would it be better to leave them at whatever level they're at after use (typically around 20%)? Or is it bad to store them at that low a level?

    Is the best thing to in fact invest in a Phantom Angel?

    Obviously, given the cost of them, I want them to last as long as possible!

    Thank you.