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Barely used batteries with poor life (4200mAh)?

Discussion in 'Phantom 2 Vision + Help' started by Airbiscuits, Jun 3, 2015.

  1. Airbiscuits

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    Hello!
    I bought my P2 Vision+ a few months ago and have done around a dozen flights. I never recall getting very close to the 25 minute flight time claimed in the specs. I understand that how you fly makes a difference but after some test sessions hovering I still was not reaching 20 minutes. So, looking into the batteries:
    Battery 1: All 3 cells at 4200mAh at 98% charge (charging from about 20% life to full without "overcharging") gave me a flight time of 18 minutes.
    Battery 2: Cells 1 and 3 were at 4200mAh and cell 2 at 4120mAh at 98% charge with last flight time of 12 minutes.

    Both flights were about the same conditions. I've never put the batteries in extreme heat or other conditions not good for them. Battery 1 has been cycled 8 times and Battery 2 has been cycled 5 times total. So, these aren't heavily used.

    Did I get lemons for batteries that I should return? Is anyone else having this problem? I've done some searching around and have found someone commenting that the cell difference I'm experiencing is at least a problem, but these also are not even close to the claimed capacity! Please help! Thanks in advance.
     
  2. msinger

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    18 minutes is a very good flight time. The advertised 25 minutes is the max under the most perfect conditions that you'll never see :)
     
  3. Airbiscuits

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    So what about the batteries not even meeting specification (5200mAh)? False advertising or do I have bad batteries? 18 minutes is probably the longest flight time I have had. A few weeks ago I had a 7 and 9 minute flights with these two batteries, respectively.
    Unfortunately I didn't have time or my PC with to check out what was going on as I was far from home and just tried to get what I could out of the limited time.
     
  4. RoyVa

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    I think the flight time advertised is from 100 percent charge until the battery is les than 8%. We all normally maintain a 20-30 % RTH when the battery gets low landing with a reserve still on the battery. We can afford to cut it to close as the plane will auto land where ever it's at and makes no difference what under it at 8%. So we have to be back on the ground with 5-6 minutes still in the battery'.
    If you get 18 minutes flight and still have 5 in the battery you just used 2 minutes or more getting back home. With. 1 to 1 1/2 % error rate that pretty close to the 25 minutes splitting the times up.
     
  5. yorlik

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    I bet those who get 40+ cycles out of there batteries prob typically stop flying with more than 60% or so battery reserve left.

    I bet those who get 30-40 cycles out of there batteries prob typically stop flying with more than 50% or so battery reserve left.

    I bet those who get 20-30 cycles out of there batteries prob typically stop flying with more than 30% or so battery reserve left.

    I bet those who get less than 20 cycles out of there batteries prob typically stop flying with less than 15% or so battery reserve left.

    I have never seen such a comparison made..... I would be interested in folks chiming in if these match what they have found.

    I typically have flown my 40 or so cycles for around 4-6 minutes each, ending with 60-75% battery left. Both my batteries today show HIGHER capacity than new (54xxmah)....

    I found in my EV, using only top 30-40% of lipo battery made it last basically forever for 4 years, like new, no range reduction at all; once I began using 60-70% with high current draws each day it basically went downhill in a couple months. My case too was a few cells that never charged back up fully from this with the wimpy 'balance' scheme built in. If the EV mfgr did not give me near full refund, I believe I could have charged those weak cells myself and been back to like new....
     
  6. Airbiscuits

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    I would like to see what other people are getting as well. As I stated, regardless of whether I pulled off an 18 minute flight or not, it doesn't justify having nearly new batteries with 4200mAh at 98% and one of them not matching cell levels.
    If I got 18 minute flights every time I would probably not have any complaints, but that isn't the norm. My goal was to get a sanity check from the community before pursuing getting my batteries replaced to see if mine were lemons or not.
    Driving out of town to a cool place to fly/shoot video, in my opinion, is a waste of time when you are getting 6 to 8 minute flights using 70-80% of your battery. I would be shocked if I am the only one that feels that way after buying a $1200 product that claims much more.
    From doing some more research I'm finding LiPos don't experience battery memory, but I have read that storing them at full charge for long periods of time can lead to permanent performance drop of the battery - neither of which my batteries are subject to.
     
  7. yorlik

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    airbiscuit, you need to get your units under control... you say 4200mah and 4120mah in first post per cell. nonsense stuff.

    your post #3 &6 also mix up units so they are too confusing to have meaning.

    a cell does not list mah in assistant, but rather VOLTS.

    so what you posted makes no sense. please repost stating proper units and then some comparisons can be made to your situation.
     
  8. Airbiscuits

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    That is correct. I mixed up the mAh specification with the cell voltage (in mV). I don't like to have my phantom on and hooked up to assistant for long because it drives my dog nuts with the chime so I mixed that up. However there is a friendlier way to point out my confusion.

    So let me narrow the focus of my concern with my battery life so maybe some of the non-unit based observations I've made can result in feedback.

    1) Is there any concern in having unequal cell voltage (i.e. cell voltages differing by around 80 mV at full charge)?

    2) What do you typically see from your DJI Vision app upon initial take-off as time remaining on your flight? I know this measurement is a rough indication, but I would like to compare with others. I had 12min and 14min today once immediately airborne on full charge (considering boot-up, wifi connection, and calibration taking place first).

    My goal in this thread is to determine if my batteries are typical or not. If anyone has any friendly advice as to numbers I can check to post by means of troubleshooting, I would be happy to provide more info. I am no expert with the engineering behind these. I just know that I am having inconsistent and abnormal flight times under consistent charging and battery handling conditions. Thank you
     
  9. yorlik

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    Airbiscuit, sorry for my reply coming across too harsh; that was not my intent at all.

    I think my 2 batteries stay within more like 10-20mv on each cell....

    But I think my flight time with 100% battery also say 12-14min typically!

    I doubt many folks can get the magic 25-30min flight time advertised anymore than they can get the 300 life cycles.

    I typically just fly 6-9minutes so no issue for me. I also believe this is why my batteries at 20 cycles each both show well over new capacity (54xx mah)..... I think flying over 10 minutes causes these batteries to begin "dying" after only 10-15 cycles...... although I do not believe they actually die but rather get so out of sync in cell charges that they become near useless and must be thrown away by most. Although yet to be proved (no one has taken me up on sending me 'bad' batteries to confirm it), I truly believe this is fixable, but not by John Doe without further testing first.
     
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  10. Airbiscuits

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    Ok thank you. Mine show over new capacity as well. I'll see what happens with them as I continue to fly full cycles on them and post up what I'm seeing.
    One factor I didn't consider (which may not be huge) is that I'm at around 6500ft base altitude so my motors are working a little harder than most P2s. I plan to document spots much much higher in the mountains so maybe that will yield worse flight times.
     
  11. justin00

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    Im on about 160 cycles of each battery (got 2)..i get same flyinh time... approx 15-18 mins as I did from cycle #1...
    I stop/land at around 20-25%.

    I suspect others who get abit longer fly even longer....kinda silly tho when it wants to come down hard at 17ish%

    But I guess stopping at 0 mins (25%) and 17% could be 3-5 extra mins....

    Also depends if your going full speed whole time or just hovering.... probs get 20+ mins just hovering...specialy in a wind free day in ATTI.... nvr really tried.
     
  12. justin00

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    Fyi i do intend to get new battieries soon...been getyting a few battery discharge errors lately I suspect due to 2312 motor uograde. Get it even just going horizontal and not ascending. No errors with friends fresh battery...so batteries getting little old. I think V3 owners will run into same error when there batteries get abit used like mine..... time shall tell
     
  13. justin00

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    always happens like this!!!!!!!!!!!
    so I post up 'yip generally good after 160 cycles'

    the other day after posting that I went to my local park...Since changing photo mode to RAW I now suddenly get issues were the video doesn't come back after the 10 seconds the "shutter" closes (don't think its my wifi module, as its 100% fine on JPG) problem only intermittantly happens on RAW.

    Anywho so battery is 40% and I'm bringing it in to land to reboot phantom as thats the fix for above issue... LUCKILY its at 2 ft off the ground and the battery indicator went red to 0% and she auto landed pretty hard... would of actually been no problem but 2 of the props hit my case and cause a tip off so immediatly did CSC.

    Again luckily :] no damage, not to props (went over them with a torch/magnifying glass) as I know splits/hairline cracks can occur. Took the lid off and no burnt mosfets...... Put another battery in and flies perfect.

    When I put the original battery back in it was at 17% which is the auto-land percentage... but yeah it dropped from 40% to 17% (reported 0%) in a split second... no message/error in the DJI App.

    Drained both batteries down to 0% as DJI manual states to do every every X flights (20? can't remem) I have only ever done it maybe 5 times in my 160ish cycles...

    DJI Assistant showed all cells fine... tempted to do more testing of the 'faulty battery'... maybe run it down on the ground and see what happens.. after each fligth I lose more and more confidence in the batteries..... I don't see many people reporting there batteries are lasting 300 cycles... but you would hope 300 is conversative, not like its just gonna catch fire at 300 hehe... well I hope not :p auto-self-desctruct.

    my bday is coming up soon, but soooo many other mods I've rather spend some money on than a new battery... but if I don't take this battery stuff seriously I'll have nice shiny mods, but nothing to stick them to... well besides the pile of broken plastic :/