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Lets talk battery life

Discussion in 'Pro/Adv Discussion' started by spankybear, Jul 7, 2015.

  1. spankybear

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    I was wondering if you can post how many charges you have vs % life. My battery that came with the bird have 15 charges on it and it's at 98% life. Not to sure this is a good sign...

    At that percentage is it no good?
     
  2. silverstoned83

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    While it's still too early to know for sure, having it drop by 2% after only 15 cycles isn't a good sign. I have one with 15 cycles on it and it's still at 100%.

    Have far did you drain them during the first 5-10 cycles?

    It's common practice to take a LiPo out of service once it has lost 20% of its capacity.
     
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  3. Julius717

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    My original battery has 32 cycles. Still sees 100% my other 5 range in the 4-10 cycles area and still 100% also. I keep mine fully charged at all times also
     
  4. GordonT

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    34 cycles and still at 100% store at 50% or less and charge prior to flight, always leave at half charge or less, not relying on auto discharge
     
  5. Buckaye

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    Just FYI (and just personal experience) auto-discharge works great... I find it a really cool feature of the batteries :)
     
  6. Bratinov

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    My original battery has 21 cycles on it, after the 15th charge the battery only shows 98% after being fully charged, battery life still shows 100 %.
    (Due to misinformation I fully drained the battery the first 2 times using it... )
    After I realised my mistake I did the battery break in progress, store at 50 % and never keep it fully charged for more than a few hours. Drained it to 7% and fully recharged on my 21 cycle.

    Second battery has 11 cycles on it, everything is at 100%
     
    #6 Bratinov, Jul 7, 2015
    Last edited: Jul 7, 2015
  7. gabrieldps

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    The problem with auto discharge is that it will remain some time fully charged until it starts to discharge (10 days by default), so this period will degrade the battery a little, because this some people are changing the setting to 1 or 2 days. Other thing is when it happens you are wasting almost a half of a cycle for nothing. Other thing is that you might forget it in a non flesh place, and it can be dangerous. So I think is a pretty much better and easier just left the battery discharged when you end your flighting session.
     
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  8. Chuck Young

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    I fly just about every day. Have only 1 battery but want it ready to go at a seconds notice. Never went more than 2 days without running the battery down with spinning propellers.
     
  9. silverstoned83

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    You're keeping them fully charged, but are you flying every few days or less even? Keep in mind how this can be misinterpreted by someone who has little experience with LiPo's. It's one thing to leave it fully charged for a few days every once in awhile... It's something completely different to frequently leave it for 10 days or until the auto discharge feature kicks in. It will most certainly do damage to the LiPo's lifespan by leaving it fully charged for this long, which will most likely cut the potential cycle count in half if done frequent enough, if not worse. While DJI has implemented a self discharge feature, I think it would have been even smarter to include a manual way to force the battery to self discharge down to storage level. I can see how DJI would prefer to keep it simple, but why can't there be a button sequence to allow you to manually start this feature? I'm guessing it's because DJI would prefer users to replace their batteries more frequently, not less.

    The self discharge ability is a nice feature... But it's not something that I suggest relying on, which WILL maximize the cycle count you get out of your LiPo's.
     
    #9 silverstoned83, Jul 7, 2015
    Last edited: Jul 7, 2015
  10. bobmyers

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    watch the cell balance-- when there is a .05 discrepancy between any cell, then you may begin to see declining voltages if you cant get the cells restabilized in a few charges.
     
  11. mrfun

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    OK - I'm on my fifth battery. 1 and 2 autoland after somewhere between 50 and 65% - never sure exactly when its going to happen, so I have 'retired' those (round contact). Bought three more. One of those started autolanding at around 65% 'sometimes'. It has 42 cycles. I wrote DJI, who responded that the batteries should be good for 300 cycles, unless I am 'abusing my battery'. All batteries are out of warranty.

    Lots of questions here -
    The first two became unreliable after less than 70 cycles. I did leave one of these fully charged for a long time (my vision was in the shop completely wrecked due to 'battery communication error' on the other battery and I did not know how to discharge the fully charged battery without a phantom). That battery visibly 'puffed'. My bad - I abused that particular battery.

    Q1: The other battery was maintained as per DJI specs, not left charged more than four or five days, and not exposed to cold temperatures...but I often flew it down to around 20%. On that particular battery, I did the 8% every 20 cycles (per DJI), but would spin the props all the way to 8%. I now understand that I should just turn the battery on without load and let it drain slowly down to 8% - right?
    What killed it - 20% flight times, or 8% spinning?
    Q2: The last three (all square contacts, bought within 2 months of the first two crapping out) - I have done everything per the seeming consensus of the forums. I land between 25% and 35%. Still do the 8% (lot of conflicting opinions on this - I know) every 20 cycles - but do it without load. When I know they will be stored for more than 5 days, I store somewhere around 60% charged. Why is #3 giving me problems this early in its 300 cycle lifespan...

    q2a: I accidentally left two of the three in the truck fully charged overnight when the temp got down to mid 20's last winter. I know that's bad - but is it a battery killer? and if so - it took months before I saw the problem and so far its only in the one battery?
    q2b: I fly in South Carolina where this summer has been hellish. Is flying when temps are over 100F bad for the battery?

    Q3: Aftermarket batteries - eh? 12 month warranty. I don't want to - but the 'abusing my battery' remark from DJI kind of ticked me off. Limefuel - looking pretty good to me....if anybody has crash caused by a Limefuel battery not communicating during flight - please let me know?
    I had that with a DJI battery and do not want to see the 100ft. plummet to earth again.

    In case it matters - I fly at least three to five batteries a week. Mostly in the heat and humidity but still probably two a week in the winters. I don't typically 'fly hard', but rarely do push it full throttle. I don't carry any kind of additional payload. Flying a phantom vision and a vision plus at present, mostly the plus - although the autolands happen on both machines. No puffing noticeable on four of the five batteries I own.

    Lastly (long post) - I've read the forums and everybody has an opinion. I understand opinions, but I'm looking for some kind of lithium chemo-physics genius to tell me what I'm doing wrong. I'm not trashing DJI batteries - I just can't figure out what I'm doing wrong.
     
  12. silverstoned83

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    I notice you mentioned nothing about a break in process. Did you properly break in the LiPo during the first 10 cycles? Discharging down to 20% during the first 5-10 cycles will have significant effects to the potential cycle count that you can expect, IMO.

    Same answer as Q1.

    To answer Q2A, this will not be a problem. It would be different if it were warm temperatures as this would cause the cell voltage to rise above the limit where cell damage occurs.

    To answer Q2B, flying in hot temperatures is never going to be good for a LiPo. They do not like heat. It should be considered a LiPo's worst enemy. Only a short amount of time is required for a hot LiPo to be damaged irreperably. This is the reason why I always take the LiPo out of the Phantom as soon as I land, so it can cool. As soon as I get to the car, I turn the AC on and cool it down in front of a vent.

    I think this can happen with any battery, especially if it is one of those that require a more firm push to fully seat. Having said that, if they were available for the P3, I would have a go at them... And compare how they look while under load and whether the cells stay balance in order to determine how well matched their cells are. DJI does not do a good job matching cells when they put a battery together... Which makes the break in process even more important, IMO..
     
    #12 silverstoned83, Jul 7, 2015
    Last edited: Jul 7, 2015
  13. bobmyers

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    sorry you are having those issues-- you have a lot of experience with lipos--
    I am not a chemist-- but I do own and use a lot of lipos in rc flying and I would not ever intentionally drain one to eight percent-- in my experience, when they get that low, they will never regain their original cell balance and will start to degrade, some more rapidly than others. 20 percent is the lowest I try to ever discharge to and after the battery is broken in, always between 20 and 30 percent.
    IMHO :):)
    Hopefully, the lithium chemo-physics genius will show up--- I will be watching and listening.
     
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  14. silverstoned83

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    I follow this method too.. I have also found out the hard way that LiPo's do not like to be discharged below 20%. This should be considered reserve capacity and should not be used unless you have no choice.
     
  15. DaveN

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    I came across a site that might interest all. Battery University is site that describes all sorts of batteries.

    http://batteryuniversity.com/

    There’s a great section on extending a batteries life. Although the main intent is laptop or cell phone batteries, the overall principals are the same.

    Some of the sections include:
    Crash Course on Batteries
    How to Prolong Battery Life
    "Smart" Battery

    Here’s the breakdown on the Lithium section:
    • Lithium-ion
    BU-808: How to Prolong Lithium-based Batteries

    BU-808a: How to Awaken Sleeping Li-ion

    BU-808b: What causes Li-ion to die?

    BU-808c: What the User Can Do

    BU-809: How to Maximize Runtime

    BU-809a: What Everyone Should Know about Aftermarket Batteries

    Overall it’s good reading. It's best to read about lithium batteries and temperature. I always let my batteries cool to room temp before charging, even if they have internal protection.
     
  16. mrfun

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    OK - I'm with you on the 8% - been reading that all over the place...20% is my new low end.
    but
    Break-in period? what break-in period....I must have missed that chapter completely!
    What should I do for the first 10 cycles - land at 50% ?

    As for heat - I can't avoid flying in the heat. Should I keep the batteries in a cooler or something to maintain the temperature around 75F before I have to fly in hot weather - would that help?
     
  17. mrfun

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    i knew the smart people would be over here with the phantom 3's.
     
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  18. silverstoned83

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    I was surprised not to see it in the manual myself. No manufacturer wants to make it sound like you have to baby these things in order to prevent a premature failure, they would rather make it sound effortless.

    Don't put the LiPo's in a cooler, that could cause condensation build up and cause a short. I would simply minimize the amount of time your LiPo's are warm to the touch. Using the car's AC before and after the flight will significantly alleviate heat stress on the LiPo.
     
  19. bobmyers

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    There is another line of thought -- proven-- I don't know-- but I used it to be on the safe side. On the Phantom-- 10 minute flights for 10 flights-- which actually equate to running the voltage no lower than 50% for the first ten flights. They call it "conditioning" -- I have no issue with it, so I practice that with every battery-- and to date-- no battery issues-- :):)
     
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  20. silverstoned83

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    On top of that, I suggest using the battery temp as another way to know when to land. I've noticed that my batteries never exceed 47-49°C in the pilot app after a break in flight that brings it down to 50%, in 85°F weather. In warmer climates, it may be necessary to stop the flight if the temp gets to 50°C, which could be as early as 60-65%. I wouldn't want it to be any warmer than that during the break in period.
     
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