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Charging Battery at 95%

Discussion in 'Pro/Adv Discussion' started by AirSpace2016, Feb 23, 2016.

  1. AirSpace2016

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    The DJI manual says when the battery is 95% or over to turn the battery on then charge the battery should then turn off when charged.

    I have a DJI hub charger and when I do this I have noticed that the green light flashes (on charging hub) to indicate charging and after perhaps 2 minutes I see a stready green light (on charging hub) and battery turns off to indicate it has charged.

    I noticed the other 2 that when I charged the battery in the same manner under the same conditions, the green light was steady (to indicate a full charge on the charging hub) but the battery did not turn off. Does this mean it is still charging/balancing or what?

    I have also noticed one of my other batteries upon full charge displays 98% and not 100% on full take off. None of these batteries have reached the 20 cycle amount yet so have not done an 8% discharge/recharge as of yet.
     
  2. alokbhargava

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    I do not have the charging hub so can't comment on the indications on hub lights but can definitely help you understand how battery behaves during charging.

    1. During charging battery led bars blink serially to indicate that charging is on and approx level of charge.

    2. Led stops blinking when battery is fully charged

    3. If you keep the battery for a day or so, battery may lose charge and will not remain at 100%

    4. If you try to recharge a battery that has 95% or more charge, you need to switch on the battery for further charging else it won't top up.

    5. If you wait for the days set to start auto discharge cycle, voltage will discharge to ~ 60%

    6. It's better to recharge / top up to 100% before you start flying.
     
  3. m0j0

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    Yes turn it on and charge it prior to flight

    Yes this means your battery has completed the charge. Fly it..

    I would say that you should charge your batteries or top them off prior to flight. This is critically important in cold battery temps. I would also add that running your battery to 8% like you are instructed in the DJI manual has resulted in damaging batteries. I would not discharge the batteries much lower than 15-20%
     
  4. AirSpace2016

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    Thanks for the help if a battery is fully charged shouldn't it then turn off? What I don't understand is when I topped up my batteries one of them showed 98% with a good voltage in the app and not 100% interstingly enough this battery also engaged the critical battery at 12% and not 10?

    Can anyone confirm if you are critically landing at 10% can you raise the altitude by throttling up at all or will it just maintain the altitude when you started doing this.

    Also I have read if you flick into atti mode and back or initalise the rth it won't auto descend this doesn't sound logical to me but I don't want to get into the habit of testing critical 10% battery
     
  5. Dirty Bird

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    You can manually maintain altitude & climb with <10% but she climbs slower than the normal rate.

     
  6. Mark The Droner

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    It could be your battery isn't giving you an exactly correct reading. In other words, it could be slightly out of calibration, and it could be a deep discharge would bring it back into calibration. However, 2% is not enough to worry about quite yet. MHO
     
  7. AirSpace2016

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    What is the best way to deep discharge should I fly to around 10% then charge it back up ?
     
  8. RedHotPoker

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    Fly it down to 20%, and for the last ten% let it run idle on the ground, or what I do is utilize the SIM. Trying to fly a battery down to 10%, in my experience, it would have landed on its own already.

    RedHotPoker
     
  9. alokbhargava

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    Also if you are idling to discharge and if the ambient is hot, don't risk it, use a fan to blow air onto a/c.
     
  10. RedHotPoker

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    Yes, I use a double fan, great for charging two batteries at a time.
    Or my RC and a battery. I always have the drone on one of fans while using the onboard flight sim as well.

    RedHotPoker
     
  11. Eddie258

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    Have question about deep cycling the batteries. How many are following this practice since DJI says it is not necessary and what is your opinion of this. I understand it is done to reset the electronics in the batteries but why did DJI change there mind?
     
  12. solentlife

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    Deep discharge risks damaging the battery. It serves no useful purpose. Far better to develop a sensible regime of storage / charge use.

    The DJI battery for all the hype - is a HV LiPo - and should be treated as such.

    Personally if anyone wants to continue this risky practice - then get a Telsin discharger. This then does not use the AC and the ridiculous idling method ... sorry to be blunt - but IMHO idling is bad way to do it.
     
  13. BigAl07

    BigAl07 Moderator
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    While I do agree that getting the DJI Batteries down to less than 10% has some risk (you need to be very careful how low you take it as well as how you get it there...) I have utilized the 20 charge Deep Discharge practice now since I first purchased my P3P back in 2015. I'm still flying 3 of the 4 original batteries and the only reason I'm not flying the 4th is because it's at the bottom of a lake in one of my P3Ps LOL.

    I keep very detailed maintenance logs which include monthly battery "inspections" to log the battery health, number of charges, and any noted irregularities/concerns from recent flights. At this time I note which batteries are nearing the next increment of 20th full cycle and will act accordingly. This practice has served me very well but I do have to acknowledge that I'm very easy on my batteries. I don't try to get every last electron out of them on every flight and I always try to start off with my batteries within normal flight temps utilizing heating pads etc when needed. I can tell you this much, going this route is time consuming with almost 20 batteries in my inventory (12 P3 batts and 6 Inspire batts) but I genuinely feel like it's the best practice for longevity and reliability in these Smart batteries.

    I'll be the very first person to admit what works for one may or may NOT work for others but for me it appears to have been beneficial to follow the original Deep Cycle @ 20 suggestions from DJI. If I had to guess I would imagine they discontinued this suggestion because people were indeed experiencing problems either getting the aircraft battery to this low charge level or they were causing problems by accidentally going below the 8% level.
     
  14. solentlife

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    There's a misconception among various DJI users (not pointing at you Al) ... that doing the deep discharge helps balance the cells as well. That's impossible.

    The only way cells are balanced are :

    1. By dedicated cell by cell discharge / charge monitoring - bleeding of high cells.
    or
    2. By full charge and the last part of charge is to bleed of high cells to same as low - then charge all up to full ... this sequence repeats as often as necessary to meet all cells within tolerance of each other.

    The problem is the DJI 'smart board' prevents both from being done fully ... as it reads total voltage and cuts of.

    People say the deep discharge resets mAh counter ......... I'd love to know how !! Its a myth ... because mAh capacity is related to voltage, Internal Resistance and to calibrate it requires zero to full !! Try that and you aint gonna be flying that pack again !!

    LiPo's and failures : in order of most first...

    High power demand causing overheating and puffing. Common with EDF and high power racers etc.

    Discharging too low

    Failing to store properly at 3.7 - 3.85V per cell

    Leaving in hot car in summer with sun beating down !

    Poor charge routine

    The above is based on when we talked it through at a large open meeting and flyers were asked to give their answers ... I agree it's primarily normal LiPo's - but DJI only case a HV LiPo - so IMHO same applies.

    Nigel
     
  15. N017RW

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    How are cells balanced during discharge? There's only two discharge leads.

    DJI packs do it?
    Doubtful.

    Last I tested DJI does not use the 'proper' LiPo CC/CV charge profile.
    Full voltage should occur at about 70-80% of charge cycle (CC) with remaining dedicated to balancing (CV).

    My test showed slow ramp to full-charge with no 'proper' balancing regime. (Possible this is outdated with newer batts?) Not doubting a balance attempt but no apparent CC/CV.
     
    #15 N017RW, Jul 19, 2017
    Last edited: Jul 19, 2017
  16. solentlife

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    I have had DJI batterys apart and basically :

    Main power leads we have access to along with the smaller telemetry / data power contacts as well .. but both sets are two lead only.

    The balance lead goes to the board itself ...

    It is claimed that the board controls the balancing not the charger.

    [​IMG]

    [​IMG]

    [​IMG]

    Nigel
     
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