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Cell 1 on my battery, only done 5 flights.

Discussion in 'Pro/Adv Discussion' started by azagil, Jan 16, 2016.

  1. azagil

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    Hi all,

    I just got back from a flight and uploaded my log to Healthy drones and noticed cell 1 is down a little but is giving a heap of errors ( .07-.08 deviation). I noticed it last flight aswell so did a deep cycle reset, all firmware is the latest..... Is this normal and I'm right to keep going if I continue to monitor it or should I be worried. Thanks in advance. Log below:


    HealthyDrones.com - Innovative flight data analysis that matters
     
  2. phantom13flyer

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    Definitely keep an eye on it but I'm not convinced that the battery cell information on healthy drones is all the accurate . I don't put much stock in it. That's my opinion.
     
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  3. RoyVa

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    Check the info in the DJI software. Look at cell difference there.
     
  4. 4wd

    4wd

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    It's a bit more out of line than I'd like, but I notice mine always show some minor issue with cell one too.
    I think it's pretty normal and you might find that another time it behaves better.
    Cold start and other variables like how much wind, and how you flew on the day all come into play
     
  5. msinger

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    azagil, you can try to balance out the cells by discharging and recharging the battery. Fly your Phantom until the battery is low. Then, let your Phantom on with the props and motors off until the battery shuts off. It would be a good idea to point a fan at your Phantom or at least do this in a cool place since your Phantom will generate a lot of heat while sitting still. After recharging the battery, check out the battery cells in the DJI GO app to see if they are equal -- or at least closer than the deviations shown in Healthy Drones.
     
  6. azagil

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    Thanks heaps, I will give that a go, it's about the only thing I haven't tried, I haven't had any issues as yet, just don't want it falling from the sky.
     
  7. GreggC

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    I had a battery with a cell that looked similar, I did a screen shot of the cell readings and went to Drones Plus where I purchased, they replaced it.
     
  8. azagil

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    So by the sounds of it this issue isn't a regular thing even though the cell is only .07 out..... Most of those errors came up when I was full throttle.... Would it just be that??
     
  9. azagil

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    It was similar on my last flight..... I will try a complete flat battery and recharge and see what happens.
     
  10. 4wd

    4wd

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    Something I notice with mine is that the highlighte deviations in cell one are only happening in the first few minutes - until the battery is reasonably warm, about 20C
     
  11. lenmcgilvary

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    3% is the number we've gotten froze (someone) in order to do a deep cycle reset, not the published 8%


    Sent from my iPad using PhantomPilots mobile app
     
  12. msinger

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    The percentage is not really important. When deep cycling the battery, it'll auto shut off after it has been discharged as far as the battery will allow.
     
  13. azagil

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    By the look of it mine did it right through apart from the middle of the flight. Which I'm pretty sure is when it was just hovering. The rest of the time (and when the deviations were occurring) it was pretty much full stick.
     
  14. Mako79

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    I got the same warning from healthy drones on my 17 cycle battery.
    I think this happens when the battery is auto discharging. Top up to 100% before each flight and see if it goes away.

    Then maybe give it a few days and let the auto discharge kick in and then fly without topping up and see if you get the battery deviation warning on healthy drones.
     
  15. azagil

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    Hmmm, I don't think it can be the case with mine, ever since I got it I have never stored it charged so the auto discharge shouldn't have ever kicked in. I always store at around 50 % and always charge on the same day I fly.........
     
  16. AlexSP

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    DJI batteries are pretty good quality overall, but it can get out of balance (between cells that is) eventually. It does't hurt trying but usually doing a deep discharge/full charge won't align the cells, because the smart management system will shut off the battery when the lowest reading cell reaches 3.0V or around that (and you should never go bellow 3V anyway).

    The issue here is the DIFFERENCE in voltage between cells, and that will remain until you balance the off cells individually. That means accessing each cell individually (by the taps), measuring the voltage of each and charge them all to the same level. Computerized chargers (like the HITECs for instance) can measure and balance charge LiPO packs in one shot. I've never tried mine with DJI batteries but I supposed it'd be possible.

    It's also supposedly what the smart system on the DJI batteries does too, and that's also (again supposedly) how HD can take the measurements from the P3 flight data and display in the website. I dunno if or how accurate those are (flight data and HD) but what really matters is if they are CONSISTENT. Precision is good of course, but consistency can give a lot of insight on what's going on with the battery and AC in general.

    Anyway, if there's no difference between the conformation and chemistry of the individual 4 cells, it'll restore balance and will keep it that way, if you charge with a balancer or any other technique that accesses the individual cell (there are a few around, do a search on the RC forums and websites). Most times that's what happens because batteries are made from cells manufactured in sequence or from the same batch, exactly to keep consistency and avoid big deviances.

    P.S.: You can take your battery to an experienced RC shop or instructor and see if they'd try and balance it for you.
     
    #16 AlexSP, Jan 18, 2016
    Last edited: Jan 18, 2016
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  17. azagil

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    Awesome, thanks for going to so much trouble to explain it. I have a charger for lipo's but it won't fit to this and don't think it has a cable available that would but I do 100% agree with what your saying. I looked heaps online but yes, I think it's just managed through the smart chip in the battery, I can't see anything that will balance these separately for piece of mind.
     
  18. AlexSP

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    Yeah that's my opinion too, it makes sense that if the smart core of the DJI battery handles (somehow) the charging/discharging/monitoring/balancing of cells, then it might be pretty hard or even impossible to tap on the right terminals, polarities, etc. or get past through the smart circuits to get it done with a computerized charger. So in that view it may work to try and do a deep discharge (keeping an eye on voltage instead of %) to try and see if the smart core brings it back to balance.

    Anyway, IMHO the DJI battery is high quality stuff they sure get the cells supplied by some good manufacturer like Revolectrix or some other because it's high voltage and quite stable. I suspect (just my opinion) they last quite a bit too, if we don't mess around too much with voltages and weird procedures. Basic stuff like keep it above 3.65V, never going bellow 20%, store them at 3.8V for longer periods, avoid high demands in cold, avoid extreme heat, etc.

    Again IMHO the smart management was designed like that and placed in the batteries themselves to allow exactly for a more user friendly LiPO, because LiPos for flying are pretty complex to deal even if you don't fly 3D or other hardcore stuff. I deal with LiPOs for a while in RC (copters, airplanes, cars, etc.) and other sues, there's already a pretty accepted standard procedure to keep them in good condition - a lot has been established already through trial and error so there's really no big mystery or need for confusion. But the P3 is aimed at less experienced users in general so they must compromise at some point or another, and that's also why we see a lot of mishandling and problems too I guess.
     
  19. Jeff48920

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    I am going to share my experience FWIW.
    I have had three batteries that exhibited the same problems that you (the OP) have discussed. None of the 3 recovered balance fully after a "deep cycling".
    All of the problem batteries showed over 30 "major deviations" in cell 1 when analyzed by HealthyDrones.
    Quite simply and in each case, after talking with DJI, they determined the batteries were defective and replaced them via what they call a "part swap". In all cases, I received a brand new battery within 10 days after returning it to DJI. Shipping is free if you remember to ask about it

    So my 2 cents is, if DJI is worried enough about batteries like yours to give you a brand new one, I'd take it. My guess is that DJI wouldn't do it unless they were concerned that a battery failure could lead to a flight interruption and possible crash.
     
  20. Freebird1

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    Yup. Had same experience with 1 battery. Noticed it In healthy drones log. Did the deep discharge and charge. Flew again and monitored the cell voltage in the app during the flight. Saw same results as I did in the log files. Called DJI, they sent RMA and shipping label. Got a replacement in about 14 days