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Deep discharge to 8% destroyed my battery

Discussion in 'Pro/Adv Discussion' started by J.James, Aug 23, 2015.

  1. J.James

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    Well I just had to be an idiot and went against my better judgement and did what dji recommends on one of my battery's that had 20 charge cycles on it and so I did the deep discharge thing that dji recommends even tho they nore any one else can come up with any reason for it. and any ones guesses are just that just guesses as to why its good to do. Tho none of them are very good guess considering they have no validity to them.

    WELL lets just say it turned out to be very very very bad idea and it destroyed my otherwise perfectly good battery. That only had 20 charges on it prior. and considering that they cost about $150 thats about $7+ per flight and actually even more considering that I also did the 10 flights break in on the battery to so they were not even real full flights.

    Here is what happened. I noticed the battery info was saying it had 20 charges on it. So when I was done flying I let it hover till it was at 8% and then I landed it and shut it off. (was at 7% by the time I landed and got it shut off. I then took the battery inside and let it sit for about 1/2 hour to cool down so I could charge it. I waited till it was cool and plugged it in to the charger and Went to do some other stuff while I was waiting and after about 1/2 hour had gone by that only the first led was blinking as it was charging which seemed very odd that it was still under 25% done. So I let it go some more and its still never went above the first led. and thats when I also noticed the smell of hot electronics. So I picked up the battery to see if it was the battery that I was smelling and as soon as I touched it the top was burning hot and starting to melt. WOW thats not good. So I unplugged it for about an hour and when it was cool to the touch. I tried again. and it started getting hot again with in the first min or so. But it did not seem as hot as before so I let it go while keeping a close eye on it and then after 2 more hours it still was not past the first led. So I popped the battery in the p3 and looked at the battery info. It was at 17% charge even after a few hours charging. my cells were all the same cell volts. and it said the battery was at 100% health. HUM ok now thats weird. But i thought ok maybe after a deep discharge and charge cycle that maybe it just charges real slow or some thing. So back on the charger it went then after about 3 or 4 more hours i noticed its now made it to 2 leds blinking as it was charging. Then it went a few more hours and got to the 3rd led. Woot hoo im thinking ok its charging just real real slow. Then about an hour later i noticed the leds would blink on in secession with each other then they would turn off along with the red led in the power button then It would come back on a few seconds later and then do the same thing over and over. So now Im thinking oh my charger must be of crapped out.. So I swapped it over to my other charger and its still doing it and I also checked the volts on the other charger and it was fine so that rules the chargers out. Then I unplugged the battery and waited a bit and tried to charge it some more and got the thing were it was still turning its self on and shutting off over and over. So I poped in the p3 and looked at the info it was at 58% charge and just would not go any higher even when I let it go over night on the charger it was still at 58% in the morning. So I then decided to put it the p3 and tried to see If I could run it down to 8% and try it all over again.. Took about 8 mins to drain it. Then when went to charge it again I was right back to square one. and after about 12 hours it was at the 3rd led again and then started the shutting off and starting thing again and when I poped it in the p3 to see what the info said it was back at 58% and just would not go any higher.

    So basically doing what dji said to do toasted my battery that was fine before doing the deep cycle discharge.. Well lets just say I will never be doing that stunt ever again. Tho I know why they would want someone to ruin there $159 battery after the first 20 charges........ So that you can bust out another 159 and buy a new one OR deal with the nightmare of an ordeal to try and get dji to honor any warranty or wait weeks for them to send a new one.
     
  2. Oso

    Oso

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    A sad story, but thanks for sharing to help everyone else.

    I must say that you are seriously brave for letting it stay plugged in overnight after you had the initial issues. I would be too nervous to sleep.
     
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  3. msinger

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    J.James, are you sure you just don't have a defective battery? The DJI warranty might cover it since it's less than 6 months old and charged less than 200 times.
     
    #3 msinger, Aug 23, 2015
    Last edited: Oct 27, 2015
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  4. Jbundy63

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    Sorry to hear that, I have done that a few times and have over 50 flights on each battery. I have also taken them down to 8% but have somewhat gotten away from going that low, I know they say to do that every 20 cycles or so. Mine have been fine, could be due to that or possibly a battery just for some reason gone bad.
     
  5. Jbundy63

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    Agreed I would be pretty nervous to keep trying to change. My luck it would blow up!
     
  6. kdrak

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    Well some cell went bad and I am not sure it it went bad due to low voltage. Anyway you never drain a lipo below 25% flying or hovering. You should drain lipo by consuming the minimum voltage so you will avoid over heating and swelling issues. So you can drain the lipo with a charger or just with stand by in your aircraft , not with hovering or flying
     
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  7. jryser

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    This is very good to know.


    Sent from my PT beating heart
     
  8. iquadtography

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    So never take your flts past 25% Batt?
     
  9. Allclear

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    I've revived dead batteries by throwing them in the freezer for a couple of days, then trying it. Haven't had to try it with my phantom though.
     
  10. hidaven

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    Forget about percentages. These lips are NO different than any other lipo on the market. You don't want the RESTING voltage to go below 3.75 per cell. With a load that equates to 3.35 to 3.40. Watch the voltage number on the top of the screen.
     
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  11. Joao Carlos

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    So what is the verdict? I have 2 batteries approaching 20 cycles soon... should I drain to 8%: yes, no, doesn't matter? After that can I routinely use the craft until 8%? I have read many different versions around, again feeling very insecure with DJI stuff.
     
  12. Chris Vedeler

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    Here is an interesting read:

    http://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries

    Not sure it the same information applies to the LIPoly batteries. If so, then deep discharges and heat are the two biggest killers of battery life.

    I don't cycle my batteries intentionally. My batteries are there to fly my P3 and as long as they give me a reasonable number of charges then I'm happy. If I happen to make a long flight then I drain them lower. Usually I bring the bird home around 30%.
     
  13. Cacc

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    My longest running Phantom 3 battery is at over 75 charges and I have never brought her below 20% and she still remains at 100% health. Deep cycle MIGHT be just a myth or something you had to do with LiPo batteries that didn't have their own built in controller. If it is getting that hot on charging, it seems like you just have a defective battery and would contact DJI about it.
     
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  14. Norm Walker

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    Hi Guys
    I am a new soon to be owner.Delivery in a couple of days hopefully.
    Have been doing lots of training on sim.
    Ordered a spare batt with the P3 and was wondering how long they take to charge???
    I have purchased the Advanced model and believe they are a bit slower than the pro..
    Any info much appreciated.
     
  15. Mako79

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    I did the 8% at 20 cycles on my P2 OEM batteries. 4/5 was sent back because they puffed up or went into early auto land. I sold all the replacement P2 batteries and used aftermarket Venoms and avoided going below the 25-30% and no more 8% discharge. The 8% discharge is to simply re-align/recalibrate the readings on your app and this will kill your battery. I will do the same on my P3 batts and never let it go below 25% EVER!.

    Also, has anyone done an autopsy on the P3 batts? I'm really intrigued if they are really 4 cells or are they 8x2 configuration in parrallel. Why am I intrigued?? Because the P2 batts were never true 3 cells. They were 6 batteries running at 3x2 parallel in series. What does this mean?? When charging, there is higher chance that the balancing between the parallels are NOT even.

    An analogy... lets say you have a dog sled team. Is it easier to feed 3 large dogs in 3 separate cages? Or is it easier to feed 6 small dogs, 2 in each of the 3 cages and hope they are all the same weight and all pull the same power?. Now the problem is that if 1 LARGE dog fails, you can spot it immediately.. if 1 in the 6 SMALL dogs fail, you cant see because the other small dog is pulling harder and covering up for the weak dog. This is why auto landing occurs mid flight and never at ground level. You don't see the "dog" cark it until you start whipping.
     
    #15 Mako79, Aug 23, 2015
    Last edited: Aug 24, 2015
  16. Chris Vedeler

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    I wonder if DJI recommends the 8% discharge because they know they will sell more batteries that way? My understanding is that Lithium batteries don't have a memory and deep discharge kills the longevity of the battery. So what is the point of cycling them?
     
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  17. Phantom751874

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    I took all 4 of my batteries to 8% on their 11th cycle, cycles 1-10 from 100% to 50% (break in). Only one battery is past 20 cycles now at 24, the other 3 are close. I didn't plan on going back down to 8% again, maybe 20% but not 8%. I can't remember what DJi says as far as what percent to go to but the only reason to go lower every 20 cycles is to ensure the displayed battery percentage stays accurate. Other companies that make products that use LiPo batteries tell you the same thing (Apple etc.).
     
  18. bobmyers

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    IMHO-- 8% is too low-- 10 to 15% is all that mine will get after 20 cycles
     
  19. Zerone

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    Yup! This is the inside of a P2 battery. I cut this image from a YouTube video which I now can't find.:rolleyes:

    P2-LiPo.jpg
     
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  20. Johnny Chow

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    When you do the deep cycle of your other batteries, land it at 15 - 20% and let it cool down, switch it on and sit on the table let the % drop to 8% then switch it off. cool down and then charge it back to 100%. Never let each cell drop lower than 3.5v, it will damage the battery cells.