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Battery charging question

Discussion in 'General Discussion' started by Alka, Dec 24, 2015.

  1. Alka

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    Been reading a lot of info on flying and my head is going to explode from Phantom overload. Have read that battery should be full charged before flying. My question is what happens if I have about 60% battery left and land the quad and shut off motors for a minute and than continue with a flight. Now I am taking off again with a 60% charged battery. Am I at risk for a power failure. And If not what is the difference from starting a flight at 60%.
    Al
     
  2. Gsujeff55

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    Do it all of the time. Zero problems.
     
  3. DAP-UAV

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    I have read many different explanations for this problem. These Lipo batteries are "SMART" supposedly meaning they do things are their own. I can say there are too many stories of people taking off with less than fully charged battery and have had power failures of some sort. The manual clearly says only fly with a fully charged battery. I think flying, landing, taking off again is ok, but if you turn it off, something happens with the battery when it's turned on and used with less than a full charge. So I always start with a fully charged battery and do not turn it off until I am done with it. It I have to turn it off for some reason, I change the battery to a fresh one. I think it's a software issue but I am not a computer tech nor an electrical engineer. I would rather be safe than sorry until they figure it out. The last firmware update was supposed to address a battery issue that may have something to do with this issue. Hopefully someone smarter than I on this forum can help. There is a guy on the forum who seems to really know his stuff and helps everyone lot. We all own him some thanks for all his efforts. His name here is msinger. Maybe ask him directly.
     
  4. msinger

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    It's a good idea to watch the battery voltage in the DJI GO app to ensure the battery cells do not drop below 3V. If that happens, your battery will most likely shut off and your Phantom will drop from the sky like a rock.

    You could certainly take off with a battery that has a 60% charge. It would be best to ease it up instead of taking off like a bat out of hell. Any type of quick and/or full throttle maneuvers are going to cause the battery voltage to temporarily drop. When your battery is low, you could easily reach the 3V danger zone.
     
  5. DAP-UAV

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    excuse my typo... on their own. Is that correct Gsujeff55?
     
  6. DAP-UAV

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    Because of what msinger just stated is why I do what I do with batteries. I think the last guy that lost his bird to a power failure and took off with less than full charge had zero problems before that. Just saying.
     
  7. Gsujeff55

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    That is correct, sir! While we're at it, though, a typo is when you accidentally hit the wrong button not accidentally use the wrong word.

    Back on topic, I have never taken off with less than a full battery after it has been removed from the phantom or even powered off. I have shut the motors down and taken off scores of times, but never powered the battery off. I cannot comment on what happens in that instance.
     
  8. DAP-UAV

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    Got it. OH and thanks for all you help. Merry Christmas to you too.
     
  9. Gsujeff55

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    Well, you asked.
    I do hope you have a Merry Christmas!
     
  10. Alka

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    So from the sounds of it I am ok if I don't turn the battery off in between take offs. This phantom is awesome. Everyday pushing a little father with it.
    Al
     
  11. msinger

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    Turning off the battery will not cause any issues. You need to be aware of your battery voltage.
     
  12. Mark The Droner

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    Many of the "drops from the sky" seem to be with folks who fly with a battery that had been auto-discharged to some point but is still reading enough charge to make them think it's still safe to fly. Others who fly with a partially charged battery that had been used earlier in the day don't seem to have problems.
     
  13. tcope

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    After much testing, reading and comparing notes, here is my input....

    You can say, always start with a fully charged battery if you want to avoid _any_ details on the subject. It's nice and safe. However, it offers no information on the subject so it's more or less a blind statement. There are two things you need to keep in mind about the battery... once it drops to a critical level it will turn off and, that percentage you see on the Go app or the LED bars you see on the battery.... not completely accurate when the battery is not under load. Now don't get too worried about that critical battery turning off statement. It's not the same as the battery simply getting low. It's important to keep this in mind.

    As msinger mentioned, I'd highly recommend turning on (in setting) the battery voltage being displayed in the Go app next to the battery percentage. It's more reliable and detailed.

    If a lipo battery is allowed to sit around, you put it into the Phantom and you then look at the percentage it _might_ show you a number much higher then is actually correct. I can't know for sure (as I can't talk to anyone in the know at DJI) but I'd say that a battery coming out of discharge state may stand more of a chance of reporting an incorrect battery level. Once that battery is placed under load (especially something like full throttle) the battery shows it's true voltage. Still, this is still not usually an issue. What we are seeing now is the perfect storm... a lower than "full" battery, full throttle and colder battery. A colder battery is probably going to report lower voltage as well. The thing to keep in mind is that lipo batteries go from good to low _VERY_ quickly. They are designed this way. Here is an example:

    This is why it's recommended that you start to land around 30%.

    But the thing to keep in mind is the voltage amount. I'm a little fuzzy on the numbers (others should be able to correct me) but I think the number you need to look at is right around 3.3v. When you get to that mark you should start to land pretty quick.

    Now the issue. If you leave a battery sitting around and/or in discharge state it might report at something like 3.5v which might be around 60%. However, it might really be lower, especially if it's cold. So you start to use this "60% battery" and take off. It's cold and you kick in full throttle. Well, that voltage takes a nose dive, let's say to 2.xv which is critical (2%?) so it turns off.

    If you have been flying with a battery then you've been drawing current and the battery is warm. So it's much more likely that the percentage and voltage being displayed is correct.

    DJI has also changed the characteristics of the battery in this last update to prevent this perfect storm. When the battery is cold, it lowers the amount of full throttle so the battery's voltage does not drop as far. Perhaps they adjusted the critical battery level as well... we don't really know. We do know (from FranknFly) that the beta testers have tested this firmware and it appears to work.

    MY recommendation... start with a charged battery. If you've been flying with a battery and land with a good charge, that charge amount is probably correct so you should be fine starting up again. Avoid using a battery that is in partial discharge when it's been sitting unused for a day or so. Change your auto discharge to a higher number and use a manual discharge method such as the light devices for sale online.

    *** Just my 2 cents ***
     
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  14. Milly

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    Any links for these lights that help you discharge a battery?
     
  15. tcope

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    You can search ebay for "Phantom 3 discharge".
     
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  16. Milly

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    Thank you.
     
  17. msinger

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    This style discharger works with Phantom 3 batteries.
     
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  18. SkyKisser

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  19. GlennG

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    I wouldn't do it. Always have a full battery. Some have done it with no issues but a bunch have problems. I just don't do it.