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Battery life percentage....

Discussion in 'Pro/Adv Discussion' started by driehl, Aug 17, 2016.

  1. driehl

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    My battery is showing 20 cycles and 95% life remaining... why? How low am i ok to go on my % of life remaining? Battery operates perfect.. voltage is good and i always watch on the screen when flying. Is it possible to make this number increase by deep cycling?


    Sent from my SM-N930F using PhantomPilots mobile app
     
    #1 driehl, Aug 17, 2016
    Last edited: Aug 17, 2016
  2. flyNfrank

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    It's saying the battery has been charged 20 times and has a life of 95% remaining.
     
  3. driehl

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  4. flyNfrank

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    I just checked my last flight and it shows the battery used on that flight with 53 cycles and 92% life.

    As you probably notice there seems to be a noticeable difference in each of our battery stats. The reason is due to I'm not flying with the more recent firmware. The smart battery firmware is the #1 contributor to most if not all the issues the P3 has had. They want us to only use their batteries. They want the batteries to last X amount of charge cycles or flights. I'm guessing now the way the batteries are set, they will have less charge cycles with those of us that live in colder climates. This could explain why they are referenced as Charge Cycles, and not Flights or Hours?

    So to answer your question, your stats are normal if you're using more updated or recent firmware. And if you are not use to or familiar with year old firmware, then it's likely to be acceptable for you.

    Edit: Based on the provided data, if I get 53 flights for every 8% battery life, I should be around 636 some flight per battery using the firmware I currently use.

    On your setup, you are at 20 flight for every 5% battery life, this puts you around 200 flights.
     
    #4 flyNfrank, Aug 17, 2016
    Last edited: Aug 17, 2016
    Digdat0 likes this.
  5. sonof40

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    Life means the life of the battery, not the life of the current charge.
     
  6. driehl

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    Yes i get that.. so at what percentage do they suggest no longer using the battery? What firmware and phantom are u using?

    Sent from my SM-N930F using PhantomPilots mobile app
     
  7. Mark The Droner

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    I've never seen a recommendation by DJI for what percentage to retire the battery. I've also never seen or heard of a battery being used with a useful life below 70%. Even below 80% is rare.

    I think the main thing to be concerned with is balance of the cells - not whatever percentage of life your battery happens to have.
     
  8. yorlik

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    I cannot speak on the newer batteries, although I would suggest there is no reason for them to have changed how they calculate % Life remaining. But after extensive testing on the P2V3 batteries, I can de-mystify this variable.

    It has nothing to do with your battery's remaining capacity!

    It is simply a math equation! The equation for P2V3 is: %Life=100*(300-CYCLES)/300

    They sold the P2 with battery life CLAIM of 300 CYCLES of useful life. Thus they count down this math term based on difference between your number of cycles vs. this mythical magical marketing term "300 cycle life."

    As Markmd stated, few have gone over 70-ish%, or 300-(70*300/100)= 90 cycles.

    Remember since they count actual power in vs power out (coloumb counting), the CYCLES is not a direct correlation to number of flights; if you typically fly down to 50% charge remaining, then a CYCLE for you is 2 flights...

    So unless they stopped marketing their batteries as X number cycles worth of charge for full life, you guys will have to compare notes and find that magic 300 number to use in your model.

    BTW, a MUCH better % life remaining term IS available to you and DOES give you a decent idea of when to retire your battery. Again, simple math term: REAL % life remaining = 100*(FULL_CAPACITY_NOW)/(RATED_CAPACITY). Rated_capacity in my P2 case is 5200mah. This gives you a percentage of YOUR batteries dropping capacity vs when it was new. This term unfortunately only partially identifies (takes into account) a bad single cell: if that happens, you may get the "instant drop from 60% to 8%" syndrome - even with an otherwise good battery.
     
    #8 yorlik, Aug 18, 2016
    Last edited: Aug 18, 2016
  9. yorlik

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    For kicks, using your P3 's 95% & 20 cycles: 95%=100*(X-20)/X

    X=400. So dji believes the P3 battery is marketably good for 400 cycles... Compare that other P3 & & cycles to see if it is a constant?

    So when is a battery "no good" anymore? Same as your nicads, nimh, lithium, any other battery: when the useful recharged life is lower than you are willing to live with. My other equation above shows it. As batteries age, their capacity after recharging diminishes. As this capacity diminishes, so does flight TIME in the air. When your new battery can fly 17 minutes, and the used one can only fly 8 minutes, does that make the used one "no good" anymore?

    Obviously a subjective answer.
     
  10. Dronason

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    In thread Life expectancy
    We were comparing our batteries lifes at post #6 and #7. I have similar values as yours.
    I am always using latest firmware and I think (I remember that from another thread) that BigAl07 was not using the last firmware that is also updating the batteries.
    Before that update I don't remember to have seen a value bellow 99%.
     
    BigAl07 likes this.
  11. BigAl07

    BigAl07 Moderator
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    This reminds me I need to see which FW I'm running and possibly update. I thought I could figure it out via HealthyDrones but I don't see it listed there either. I'm going to be doing some routine inspections tonight to get ready for a busy weekend and I'll note the current version and update this thread accordingly afterwards.

    Here are the values from the thread noted above (late July time frame):
    #1 53 Charges, 99% (9 hr 41m 59s logged)
    #2 51 Charges, 100% (9 hr 41m 23s logged)
    #3 43 Charges, 98% (9 hr 2m 41s logged)
    #4 58 Charges, 100% (12 hr 16m 54s logged)
    #5 7 Charges, 100% ( 0 hr 46m 09s logged)
    #6 4 Charges, 100% (0 hr 57m 53s logged)

    What I find interesting is what happens AFTER I do a "Deep Cycle" on the battery. Take #1 for instance.

    #3 on July 27th
    43 Charges, 98% (9 hr 2m 41s logged)

    #3 on August 18th (Deep Charge on 8/3/2016)
    44 Charges, 99% (9 hr 42m 26s logged)

    See the difference? It went from 98% Life to 99% life even after adding more flight time (not a lot though).
     
    #11 BigAl07, Aug 18, 2016
    Last edited: Aug 18, 2016
  12. Dronason

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    After our posts I thought that my fly style was probably harder and I used the battery usually up to bellow 30%. Assuming a clever firmware :D that would explain such difference.
    I think now that there was a bug in older firmware that make the lifetime not going really down or really slowly. Only after last update I have seen a more realistic figures. Such batteries have a limited number of cycle and as it is a critical components, 200-400 cycle seems to be reasonable. After it is up to you to decide when to change them, I don't think that DJI use programmed obsolescence in their product, they just make a new generation with incompatible batteries P2 - P3 - P4.
     
  13. yorlik

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    So it appears dji learned from their wrong LIFE% algorithm on P2 (based on a marketing value) and indeed changed to a more meaningful algorithm - the one I posted above in #8....

    YOU can confirm this simply seeing what YOUR CAPACITY-NOW/CAPACITY-NEW number is - bet you find it is the % life you show above!

    My P2 batts with 35-50 cycles showed 103-105% LIFE left thru about 35 charges; they now show about 96-97% also, and my flight time is same as when new. Of course I quit using the dji crude PS to charge them around 10 cycles into their lives. I let my battery spreadsheet calculate both LIFE% in columns right next to the dji reported LIFE% value; one is identical to dji value (nonsense) and other tells the REAL life left story.

    So don't ASSUME your 98-99% life left values are nonsense. If your battery has CAPACITY-NOW value at nearly same as new mah then this is TRUE - irregardless of number of cycles. Realize the 1,000's of 18650 tiny batteries that make up a Tesla EV are often at near new capacity 5+ years after daily use!