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Battery Alarm going off at 56% ?

Discussion in 'General Discussion' started by gfinney49@gmail.com, Mar 3, 2014.

  1. gfinney49@gmail.com

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    I have noticed on the last two or three flights that one of my Phantom 2 batteries is giving me the alarm when it says 56% I discharged it a couple of weeks ago and recharged. My other battery works fine and alarm goes off at 30%. What am I missing here?
     
  2. Seahorse

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  3. Pull_Up

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    Does it give you the alarm when you have one of the sticks at or near the end of their travel? I get this occasionally around the 52/53% mark with one of my batteries. As soon as I relax stick pressure back from full travel the alarm stops - this seems to happen only in colder temperatures (about 6 degrees C or below). I don't see any further issues once I get below 50% until the first level alarm kicks in as it should.

    If your alarm doesn't go away or it kicks into low voltage autoland then it might be worth plugging into the Assistant and seeing how the cells are balanced or if anything else looks odd. If the battery has more than 20 charging cycles on it and you haven't done a recommended deep discharge as per the manual (down to 8%) then it might be worth doing that as well. If everything looks ok there and you can't use the full capacity then it's probably time to refer back to your dealer...
     
  4. gfinney49@gmail.com

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    Thanks for the heads up. I will go into assistant and check....and if needed discharge again to 8% and charge back up. I have not noted if I move the sticks and the alarm stops. What if I keep flying down to 30% on that battery? Snowing and wind blowing today to take it up! Again thanks.
     
  5. Pull_Up

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    It doesn't happen every flight, and like I say on mine the warnings stop anyway after it drops below 50%. The exception is as it gets down to the 20s % a big stick movement, especially a climb with all 4 motors gunned, can result in a voltage drop big enough to set an alarm off - but again I just relax the sticks and fly a bit less aggressively until the alarm kicks in at my setting (I've got my level 1 set to 23% for example).
     
  6. gfinney49@gmail.com

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    I have attached screen shot of battery reading...as far as I can tell, everything seems to be ok?
     

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  7. Pull_Up

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    Yup. Do the deep discharge - it apparently helps calibrate the smart battery's circuit to give a more accurate % reading and might fix the problem. If not, try easing off on the power next time and see if it stops as I said.
     
  8. gfinney49@gmail.com

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    Will do....thanks for your help.
     
  9. gfinney49@gmail.com

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    Ok, I discharged last night to 5% and charged back up on my #1 battery that was giving me problems. Beautiful day today and no wind so put her up. Flew the first (good) battery with Dronexpert gimbal for almost 15 min. before the 30% warning. Fine...then put in the battery in question for another flight. Was not doing anything erratic...just smooth and simple...no big stick movement and sure enough the warning goes off again at 54%. Bring her in and said what the heck...so back up in the air I go....it was not more than 15 seconds the alarm goes off again at 49% and she starts dropping. Had to give it full up to get her home port. So I immediately did a battery reading and do not see any bad signs (that I know of) with the battery. All cells reading good levels and the precent in the upper 40's. Guess I will just have to give in and say it is a bad battery? Can you all give me any more advice on this situation? BTY- Tried out my course lock and home lock today as well...everything worked great. Thanks.
     

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  10. Pull_Up

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    One cell is obviously reading a lower voltage, but I don't know if it's a big enough difference from the other two to account for a low voltage autoland kicking in. Hopefully someone more versed in lipo balancing will let us know. If it is, then it's chat to dealer about a replacement time as you've got a bad cell (it happens). If it's not low enough to account for it then it might be worth sending the battery off to be tested more thoroughly anyway...
     
  11. gfinney49@gmail.com

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    Thanks Pull Up - I just talked with Bruce at Atlanta Hobby...after 15 days it is left up to DJI. I went to their trouble/support site and filled out the form about the battery. We shall see, but there is something that is not right with this battery. I am like you, it is probably one cell about to blow and kicking off the alarm. Hopefully I will get a reply in a day or so. I really like having two batteries when I go fly. I watched the video from the bad battery and got 7 min. out of it before alarm went off. When I took it back up I only got 36 seconds of flight time giving it full up to get it home. So the reading must be close since I flew 14.5 minutes on the good battery. Thanks.
     
  12. Pull_Up

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    Yep, something's not right. And at the price they cost then they need to be right. I think the air time we get with them is amazing when they work right - but for that money they need to be perfect!
     
  13. ElGuano

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    For 0.06v difference at the end of flight, that's not anything to be concerned about generally. What does it look like when you fully charge the battery? How long does it take to go from 2300 to full?
     
  14. gfinney49@gmail.com

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    Yes the assistant readings look good....but there is something bad going on with this battery...like I said today flew 7 min (which is half of my normal flight time with the good battery) took it back up for about 30 seconds and had to limp it home with full up. Reading was around 50% when all this took place. I do not time how long it takes to charge the batteries? When it is charged I unplug it! I will let DJI figure it out when I send it back to them. Thanks.