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Battery Interpretation
350 12 2017-3-19 17:59:54
tvl
Student Pilot
Flight distance : 60283
United States
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I'm now learning to utilize Healthy Drones. I took a snapshot of one of my battery logs (Battery cells minor & major deviations)

Minor deviations on cell 4 was almost in the yellow. This is a new battery I purchased about 4 weeks back and has been charged only 4 times. Does this indicate anything I should be concerned about or is this completely normal as long as all pointers remain in the green.

Battery.jpg
2017-3-19 17:59:54
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Lb650
Beginner
Flight distance : 371174
Canada
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Ive been wondering the same thing as both my batteries read the same on cell 4.  Tho I have 25 charges on them and only just started using healthy drones I have wondered if this normal
2017-3-19 18:44:33
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Mobilcams
Intern Pilot
Flight distance : 533021
Canada
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I'm gonna get a lot of flack for saying this but run the battery in the phantom until it turns off automatically then charge it. I resolved this inbalances in my battery by doing this. It's not suggested to do this always but it will work.
2017-3-19 18:54:02
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Mark The Droner
Intern Pilot
United States
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The battery is fine.  49 mv (.049 volts) deviation is within acceptable range.  
2017-3-20 02:16:56
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Quamera
Hobbyist
Australia
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Lb650 Posted at 2017-3-19 18:44
Ive been wondering the same thing as both my batteries read the same on cell 4.  Tho I have 25 charges on them and only just started using healthy drones I have wondered if this normal


It is strange that it is almost always cell 4 that is lagging the rest, I don't expect anyone will have an answer including DJI but it is still very curious.

I would be very cautious of any new battery with a fully charged cell deviation of 0.05V or 50mV. Watch it carefully when flying because the deviation will usually increase under load and can then easily exceed the major deviation. That throws up a critical warning in the Go app which can subsequently reduce the available power to the Phantom. Not what you really want from a newish battery.
2017-3-20 02:45:12
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Mobilcams
Intern Pilot
Flight distance : 533021
Canada
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Here is a graph from Healthydrones in the trends section of my batteries.. This battery was giving me readings like yours until I did a deep discharge.. It stopped having constant deviations afterwards as confirmed by the chart you see here.

Deviation

Deviation
2017-3-20 11:59:24
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Quamera
Hobbyist
Australia
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Mobilcams Posted at 2017-3-20 11:59
Here is a graph from Healthydrones in the trends section of my batteries.. This battery was giving me readings like yours until I did a deep discharge.. It stopped having constant deviations afterwards as confirmed by the chart you see here.


That is a great result MC and your graph is impossible to dispute. You obviously jolted the slightly recalcitrant cell into line with the deep discharge That says there would definitely be little to loose and plenty to gain by trying the same thing with larger deviations as well. I assume you did discharge below 20% and fully recharge a couple of times to (attempt to) rebalance the cells first with minimal effect.

It will be interesting to follow that battery to see how it compares with its mates in later life. It is very likely that it won't holdup quite as well but meanwhile the battery is performing well. It could be likened to a major childhood deformity or injury, an operation can improve the problem and give the child quality of life as a young adult but as they age arthritis and other problems will often emerge.

Despite your results and some other opinions on the matter I would never do a deep discharge on a regular basis on a healthy battery.
2017-3-20 13:41:02
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tvl
Student Pilot
Flight distance : 60283
United States
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OK, I have another question or two:

What is the proper or best method for doing a deep discharge?   ...............  power up the drone and let it run at idle until the battery is drained????  Hopefully there is a better method than this!
2017-3-20 15:28:43
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Mobilcams
Intern Pilot
Flight distance : 533021
Canada
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Quamera Posted at 2017-3-20 13:41
That is a great result MC and your graph is impossible to dispute. You obviously jolted the slightly recalcitrant cell into line with the deep discharge That says there would definitely be little to loose and plenty to gain by trying the same thing with larger deviations as well. I assume you did discharge below 20% and fully recharge a couple of times to (attempt to) rebalance the cells first with minimal effect.

It will be interesting to follow that battery to see how it compares with its mates in later life. It is very likely that it won't holdup quite as well but meanwhile the battery is performing well. It could be likened to a major childhood deformity or injury, an operation can improve the problem and give the child quality of life as a young adult but as they age arthritis and other problems will often emerge.

Definatitaly wouldn't recommend doing a deep discharge regularly. Every 20 cycles though you should (even according to DJI) discharge to at least 8 percent.. I have had little problems with it since then..
2017-3-20 15:33:31
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Mobilcams
Intern Pilot
Flight distance : 533021
Canada
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tvl Posted at 2017-3-20 15:28
OK, I have another question or two:

What is the proper or best method for doing a deep discharge?   ...............  power up the drone and let it run at idle until the battery is drained????  Hopefully there is a better method than this!

There are a few that you can do.. When I did mine, I flew it till it reached 10 percent, then let it idle with motors off for a little while until it was at 8 percent.  The batteries ARE smart batteries.. They will cut out when the voltage becomes to low.. The real danger lies in leaving them at that discharged level too long.. Let the batteries cool down then IMMEDIATELY charge them up.. The damage can come from when you do not charge them immediately and the normal discharge of the batteries takes them to a point you will not be able to recover from.
2017-3-20 15:35:57
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Richafell
Beginner
Flight distance : 2185
United Kingdom
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i recently notice my No 4 cell was was lower and checked on healthy drones and found No 4 cell to be 0,108 lower than the other which they say is a major deviation. i talked to DJI and have now returned the battery to them for investigation . the battery is only a couple of months old with 11 charges
2017-3-23 03:29:35
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Dutch799
Intern Pilot
Flight distance : 17119
United States
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I connect a PAR36 Halogen 24Volt 35 Watt lamp to the P4 battery to perform a deep discharge.
2017-3-23 06:29:20
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TPVAerials
Hobbyist
United States
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Great research & in-depth info here. I'll be utilizing healthy drones with my batteries as well now!
Thanks OP & those who responded with info, this helps a ton!
2017-3-23 10:13:55
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