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What causes battery cell deviations?
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9284 44 2015-11-30
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RozBujnik
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I have 4 batteries. I've noticed each shows/showed deviations in Cell 1, and only Cell 1,  begining right after 1st charge. These start off within tolerable limit, but progress gradually. One is now showing major deviations long before the 200-300 charging cycles these batteries are said to last.

What causes these? Manufacturing defects? Charger? The bird?

Any thoughts, please share.

Using P3P.
2015-11-30
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IMI193
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United States
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3 batteries, all deviations only cell 1, does seem odd.
2015-11-30
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Fieldstone
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One of my batteries had major deviations in cell 1 with under 20 charges. I sent it in to DJI.  
2015-11-30
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DJI-Patrick
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Hi ,
The deviations always caused by over-charge or over-discharge . The cell 1 deviation is caused by Specs allocation defference ,  we have improved that !
2015-12-1
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RozBujnik
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Patrick, can please elaborate on the specs allocation defference and how to take advantage of the improvements? thanks!
2015-12-1
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cwongck
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Hi, I am flying P3P,this battery came together with the P3P less than 6 months old and only 10 charges. Using Healthy Drone, I have discovered the cell 1 deviation as follows. Should I be concerned about the battery or any advice?


Battery Printed Serial Number: 1151916307
Battery Internal Serial Number: 18106/599

Major Deviations ©
Major deviation is when a cell differs more than 0.07v from the other cells.
Please note that normal batteries can have a few of these.
An abnormal battery will:
    A) Have most of the major deviations in one cell
    B) There will be multiple major deviations per minute, and more than 10 total
    C) The deviations continue longer than 1 minute
If your battery shows all symptoms (example, another) then this is considered a more severe case of an inefficient battery and may impact the battery life.
If your battery has only 1-4 instances on the same cell, don't worry too much about it. If it has 5-10 instances - then continue to track and make sure it does not degrade:


Flight Time        Deviation        Cell 1        Cell 2        Cell 3        Cell 4
03m 52s        0.070v        3.751v        3.821v        3.845v        3.877v
03m 53s        0.075v        3.75v        3.825v        3.851v        3.879v
03m 54s        0.071v        3.748v        3.819v        3.842v        3.873v
03m 55s        0.071v        3.749v        3.82v        3.845v        3.874v
03m 56s        0.071v        3.747v        3.818v        3.842v        3.875v
03m 58s        0.074v        3.744v        3.818v        3.845v        3.875v
04m 01s        0.071v        3.746v        3.817v        3.841v        3.872v
04m 02s        0.071v        3.742v        3.813v        3.839v        3.871v
04m 12s        0.071v        3.738v        3.809v        3.832v        3.861v
04m 20s        0.070v        3.735v        3.805v        3.829v        3.863v
04m 27s        0.071v        3.73v        3.801v        3.827v        3.858v
04m 30s        0.073v        3.729v        3.802v        3.83v        3.86v
04m 31s        0.071v        3.73v        3.801v        3.827v        3.856v
04m 42s        0.072v        3.727v        3.799v        3.821v        3.845v
04m 51s        0.071v        3.724v        3.795v        3.813v        3.836v
05m 10s        0.070v        3.707v        3.777v        3.804v        3.836v
05m 35s        0.071v        3.702v        3.773v        3.795v        3.824v
05m 57s        0.072v        3.674v        3.746v        3.767v        3.791v
05m 58s        0.072v        3.693v        3.765v        3.787v        3.811v
06m 50s        0.072v        3.634v        3.706v        3.725v        3.742v
2015-12-1
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dobova
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DJI-Patrick Posted at 2015-12-1 09:49
Hi ,
The deviations always caused by over-charge or over-discharge . The cell 1 deviation is caused  ...

I hope you improved the software on board of the battery... DJI, the battery mcu ADC sample wrongly first cell very often ... check it please!
2015-12-1
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RC Noob
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Sometimes there can simply be a bias in the measurement itself.  I fly RC planes with LiPo cells and some voltage sensors show a deviation bias for one of the cells - this bias is different for each sensor.  A veteran RC pilot at my club literally uses 3 different sensors - he trusts numbers if they are consistent across a majority of the three
2015-12-1
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Rebel
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2015-12-1
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nrgwise
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Working as an engineer in the capacitor/battery/voltage storage industry, I can offer this and you can take it for whatever you feel it is worth:
Many of us like to use chargers designed to get the most charge to the cells as fast as possible, hence quick charging.  Yes, it is advantageous as far as time delay, but the worst thing you can do to your batteries.  With rapid chargers (and DJI's 100W charger qualifies considering how 'rapidly' it charges the battery) they are designed to detect a current level based on a minimal voltage.  It is possible to achieve this 'peak' level and shut the charger off - stop charging - when the battery is not actually fully charged.  What I mean by this is this: fully charged by one charger (a rapid charger) is not a fully charged battery (actual battery capacity).  To get the full potential of your batteries, the longest life, the longest flight times, slow charge the batteries.  Yes, it takes longer and you need to do some planning ahead, but a slow charge will give your battery much better 'charge saturation' throughout all cells.

I have a P2V+ and two P3P's, (I am not a commercial so I will not give a free plug) and I have a dedicated charger for both types of batteries.  I admit, these were not exactly cheap (and in fact, the P2 version is on closeout sale right now) but they provide an excellent fully saturated charge of the battery and also offer a 'deep cycle' discharge function that works great.  I posted a long, detailed post on the P2 forums a while ago, but it can be boiled down to this:  I have 5 batteries for the P2 and 5 for the P3.  The chargers I am referring to will charge 4 batteries at a time (and the RC/RC-extender at the same time).  So with the P2 I had one battery that had NEVER been charged on anything other than the standard DJI charger for the P2+ (not technically a rapid charger IMO).  I log every flight - time, location, battery used, weather info, among other things.  What I noticed very quickly was that the batteries that were charged in the slow charger consistently gave 3 to 6 minutes LONGER flight time than the one that was not in the slow charger.  But I knew this was already going to be the case.  This does not mean that the DJI charger is not good.  It just means that it does not offer the optimal charge for the batteries and is exactly what I expected.

Now for the P3 batteries...I do not have as many flights on them as I do with the P2, but the data I am recording seems to show the same trend as I would expect:  the slower the charge, the better the saturation.  And saturation is what you want for the best performance.  This is not from a quad pilot's point of view, this is from an engineer's point of view.  It just happens that as  quad pilot I can benefit from this knowledge.

So even if the charger costs, let us say 500.00, and you have 4 batteries that cost on average 130.00 each, you are talking more for batteries than for charger.  Now let us say that due to using the charger your batteries last twice as long as your friend's batteries who did not use the charger so in X amount of time your friend has spent 130 x 8 (1040.00) for batteries while you have spent 130 x 4 + 500 (1020.00) so for the first battery cycle you got twice as much time at a savings of 20.00 with half the batteries.  However, the second battery cycle you will save the entire cost of the charger.

My original P2V+ batteries, all bought at the same time, each with over 100 flights, ALL report over 95% health.  EXCEPT for the one not 'slow charged.'  It reports 79% health.


2015-12-1
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Rebel
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2015-12-1
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aburkefl
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Rebel Posted at 2015-12-1 17:30
How do you over-charge a battery?  I have never overcharged or over discharged my battery and it h ...

With the type of charger used for the Phantom 3 Pro or Advanced, the only way to overcharge the battery is by something going haywire in the charger itself (or the supply).

In the types of chargers used for "standard" R/C LiPo batteries, it isn't that difficult to overcharge a battery.

Art - N4PJ
Leesburg, FL
2015-12-1
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nrgwise
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Rebel Posted at 2015-12-1 18:46
I have always felt that slow charging was best on other types of batteries, but i was unsure about ...

The link, for me, goes to nothing - page not found.
2015-12-1
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Rebel
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2015-12-1
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Rebel
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2015-12-1
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DJI-Patrick
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RozBujnik Posted at 2015-12-2 00:24
Patrick, can please elaborate on the specs allocation defference and how to take advantage of the im ...

Sorry , It's confidencial . But please don't worry about that . If you've used  it  correcly  , it will be working fine !
2015-12-2
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DJI-Patrick
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cwongck Posted at 2015-12-2 00:31
Hi, I am flying P3P,this battery came together with the P3P less than 6 months old and only 10 char ...

Please don't worry about that . According to that data  you battery is in a good status .
2015-12-2
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DJI-Patrick
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dobova Posted at 2015-12-2 00:51
I hope you improved the software on board of the battery... DJI, the battery mcu ADC sample wrongl ...

Thank you for your warning !
2015-12-2
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cwongck
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DJI-Patrick Posted at 2015-12-2 18:19
Please don't worry about that . According to that data  you battery is in a good status .

Hello Patrick,thank you for your reply.
2015-12-2
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bill
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nrgwise Posted at 2015-12-1 18:22
Working as an engineer in the capacitor/battery/voltage storage industry, I can offer this and you c ...

I for one would be really interested in the charger you are using for the P3 batteries.  Please share.
2015-12-2
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nrgwise
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bill@northwoods Posted at 2015-12-2 07:07
I for one would be really interested in the charger you are using for the P3 batteries.  Please sh ...

this one
2015-12-2
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bill
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Excellent.  I wondered if that was it.  Thank you
2015-12-2
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nrgwise
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bill@northwoods Posted at 2015-12-2 10:20
Excellent.  I wondered if that was it.  Thank you

No problem, you are welcome.
2015-12-2
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jackamick
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DJI-Patrick Posted at 2015-12-2 05:17
Sorry , It's confidencial . But please don't worry about that . If you've used  it  correcly  , it ...

Does DJI manufacture the batteries? Just curious, but I guess the supplier might be confidential too .
2015-12-2
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DJI-Patrick
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cwongck Posted at 2015-12-2 19:17
Hello Patrick,thank you for your reply.

Glad if I helped !
2015-12-2
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Sinisalo
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I am also getting major cell deviations on a brand new battery with cell #1
Battery Error.jpg
Battery Error 3.jpg
2015-12-2
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dobova
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Sinisalo Posted at 2015-12-3 08:53
I am also getting major cell deviations on a brand new battery with cell #1

Yes, many new (and not) batteries are showing this issue.
2015-12-3
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RozBujnik
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DJI-Patrick Posted at 2015-12-2 05:17
Sorry , It's confidencial . But please don't worry about that . If you've used  it  correcly  , it ...

Thanks for replying, but it doesn't boost my confidence,  since my newly purchased battery is showing cell 1 deviation after 1 charge, despite the mysterious improvements you speak of, and I'm afraid it's going down the path of my first battery with its cell 1 reading all in the red. I hope you can understand my concern after seeing no evidence of improvements and / or not knowing where to expect them to come from (aircraft firmware being the only thing affecting hardware).
2015-12-3
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RozBujnik
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nrgwise Posted at 2015-12-1 18:22
Working as an engineer in the capacitor/battery/voltage storage industry, I can offer this and you c ...

I'll try slow charging too.
2015-12-3
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Sinisalo
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It would be nice to have the option to charge at regular speed or to slow charge included in the original charger.
2015-12-3
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RozBujnik
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Sinisalo Posted at 2015-12-3 02:53
I am also getting major cell deviations on a brand new battery with cell #1

I finally received a reply from dji support regarding major cell deviations in cell 1: rma and postage paid.

Since I couldn't get any straight answers here about the meaning of these readings I suggest you contact dji, or better still - the dealer as they seem to deal more quickly with dji.
2015-12-3
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DJI-Patrick
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RozBujnik Posted at 2015-12-3 20:06
Thanks for replying, but it doesn't boost my confidence,  since my newly purchased battery is show ...

Totally understand ! If you still doubt that , please take it to the dealers or repair center for a test .
2015-12-4
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CaveDrone
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I have had deviations on my oldest battery, but once I ran it down until the battery shut itself off.  They went away.  I am using DJI standard Charger.
2015-12-4
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gchatzisavvidis
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Today my best battery with 11 cycles in a very cold place -2 degrees celcious . I warm my battery to 25c inside my car .take off and the battery start for the first time an erratic behavior . cell #1 start major deviation for the entire flight and flight time significantly drop. I land with battery in 40% I recharge went out start again and the same thing happen... The question is. Is my battery start diying or is the cold that makes this behavior????
2015-12-21
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gchatzisavvidis
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Also do I have to update this battery to the latest firm?
2015-12-21
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quanthonytrang
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CaveDrone Posted at 2015-12-5 11:29
I have had deviations on my oldest battery, but once I ran it down until the battery shut itself off ...

I had the same problem with my oldest battery. 16 cycles and cell 1 was reporting reds on healthy drones. Took it to the dealer and was sent back to DJI. Report came back and all they did was a discharge to 8% and then full recharge and it 'seems' the problem has gone away. The discharge to 8% @ 20 cycles is designed to re-align the battery status.

I am against the 8% discharge rule with the P2 batteries as they were in a 3S2P config. Some argue the config mask errors and causes the auto land when under load. Maybe its different with a proper 'true' P3 4S batteries.
2015-12-21
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CaveDrone
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gchatzisavvidis Posted at 2015-12-21 16:28
Today my best battery with 11 cycles in a very cold place -2 degrees celcious . I warm my battery to ...

Did you charge your Battery the same day before your flight and when you started the motors did you hover at a low level for several minutes before flying?  From what I have read here,  in very cold weather, the battery resistance is much higher so when you draw a large amount of current,  the voltage output of the battery will drop very quickly, maybe below the critical shut off level.   (ohm's law)

I believe DJI does not recommend flying below 0 degrees C  (32f) for that reason.     
2015-12-21
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RozBujnik
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quanthonytrang Posted at 2015-12-21 18:13
I had the same problem with my oldest battery. 16 cycles and cell 1 was reporting reds on healthy  ...

No luck in my case with deep discharge. Did it twice, and still had major deviations through entire flight. DJI replaced battery without explanation.
2015-12-25
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AG0N-Gary
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nrgwise Posted at 2015-12-1 17:22
Working as an engineer in the capacitor/battery/voltage storage industry, I can offer this and you c ...

nrgwise - Thank you for backing up what I had learned years ago about maximum life and batteries.  Charging less than 1C will extend the life considerably, as will lighter discharging.
2015-12-26
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thelittledrone
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Hi folks,

Is 0.125V should be consider as a strong cell deviation? ( M2P battery, only 15 charging cycle)

Thanks
2020-5-26
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