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How much power do LEDs take?

Discussion in 'Pro/Adv Discussion' started by ImJim, Aug 9, 2015.

  1. ImJim

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    Hey,

    Just wondering while I'm flying at night how much power it takes when you turn on the red lights :) Any ideas? I guess these are 1,5V LEDs, am I wrong? Then how long will your flight last with these turned on during ALL the flight?

    PS: also, I bought a second battery, I don't even remember what to do when you first unbox it: empty it down to like 20%, then full charge, then use normally, OR directly charge it and then empty it?

    Thanks :)
     
  2. SteveMann

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    Way too many variables to answer your question. Most LEDs need at least 2-volts to start conducting and the more current they draw, the brighter they get. All LEDs need a series current-limiting resistor. Some have it built-into the package and some need it in the circuit. Typically, a designer will aim for 20ma.

    [​IMG]
     
  3. msinger

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    Charge it and then fly per the usual. There is not a break-in period for DJI batteries.
     
  4. Fplvert

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    Your smart battery will come with about 50% charge. Best advice is charge it fully, then run down to 50% ten flights. Then, the battery has been conditioned you can run it down more.

    DJI says to run battery down to 8% after 20 flights.
     
  5. ImJim

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    Ok now the debate can begin. Msinger says there's no point of doing the break-in process. :D
     
  6. msinger

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    ImJim, DJI does not recommend any type of break-in period for their batteries. The batteries for the P2 are nearly identical -- and, nobody mentioned a break-in period when those were released. This break-in phenomenon popped up out of thin air somewhere a month or so after the P3 was released. And, then people seem to keep recommending it without proof that there is any benefit to doing it.

    About a month ago, someone here posted a comparison between a battery that was used as I described and a battery that went though the break-in period. Both batteries were compared at a later time and there was no noticeable difference in the battery stats.

    Now, with all of that said, if you wish to go through with the break-in period anyhow, it won't hurt your batteries. You might waste some time though ;)
     
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  7. ImJim

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    Guess who did the test...

    That's me :)
     
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  8. Fplvert

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    Never mind then.

    I've had P2 smart batteries die after 39 charge cycles without conditioning.

    The P3 battery I first recieved (1 only) had 50+ charges before I got a second battery. I don't mind waisting abit of time, but I do mind waisting money on more batteries. Your mileage may vary, of course.
     
  9. msinger

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    Ah, so it was:
    http://www.phantompilots.com/threads/this-may-stop-the-battey-debate.48618

    I guess my comment is null and void though since it was not a P3 battery. Even though, nobody has shown proof that a break-in period helps P3 batteries. I guess we won't know anytime soon either since most batteries are still fairly new.
     
  10. bobmyers

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    Although I agree with msinger most of the time because he knows his facts, I will have to respectfully disagree with him on this one. This is a well proven practice among experienced competitive RC flyers who make their living flying high powered electric planes and copters in contests and as manufacturer sponsors of many types of the lipo battery products they use. Maybe not laboratory fact, but proven as good general practice for using lipos. At 150.00 per pop, it just doesn't make any sense to ignore what is the well proven practice of lipo use. In this case, there is nothing to lose by listening to the experience of the experts.
     
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  11. msinger

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    Hah, well, we can agree to disagree on this one :)
     
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  12. ImJim

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    What if you don't do the 10 first flights 50% ?

    I'm going to explain .. I did 15 charges since I have my P3A, and maybe 7 of them or more are charges I did after turning off the bird way before 50%... Most of the time I stopped flying it at 80, 70, or 60%, then charged the battery, simply cause I was making some tests. Will this still help a bit? And what if I respect the 8% rule?
     
  13. Cacc

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    I did a basic test for you today -- not scientific as I only ran it once. Just hovering in place in no-wind conditions with the LEDs on and then off yielded basically the exact same flight times (if you take in a tiny margin of error). 17m20s to 30% with lights on, 17m22s to 30% with lights off.
     
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  14. N017RW

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    Nice.

    It's likely 1000/1 ratio of motor/system current drain to LED current drain.
     
  15. ImJim

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    Thanks a million times for that. It's so nice of you :) Looks like it doesn't take anything! Well, these are LEDs though :cool: Now I'm reassured. Thanks again for taking 34 minutes of your time to help me with this boring question!:p