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Battery life
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JackCarter
Croatia
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I have a question about the battery life and maintenance.

I was advised to run battery down to 8 % before every 20th charge, in order to recalibrate it. Before I did it I tested it for battery life ( press battery button and hold it for 5 sec. ), and it showed 90 - 100 % health.

After the mentioned discharge and full charge cycle it showed me 80 - 90 % of battery life. Any thoughts ?  




2018-5-30
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DJI Natalia
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2018-5-30
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JackCarter
Croatia
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Thanks for advice...
I was just wondering could I have damaged the battery by discharging it to recommended 8 % ?
That was the recommended procedure, but it looks that after that discharge ( and full charge since that ) battery life dropped to 80 - 90 %.
2018-5-30
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DJI Natalia
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JackCarter Posted at 2018-5-30 12:46
Thanks for advice...
I was just wondering could I have damaged the battery by discharging it to recommended 8 % ?
That was the recommended procedure, but it looks that after that discharge ( and full charge since that ) battery life dropped to 80 - 90 %.


That could be one of the reasons why the battery life dropped to 80-90%. The recommended discharging rate is 10%. Moving forward, just simply the battery maintenance and storage that I provided in order for you to keep the battery life.
2018-5-30
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Mark The Droner
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United States
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DJI Natalia -

is this for all DJI Lipos?  Or is this for the P3 lipos?  

This is a new recommendation, correct?  Because this is different than what we've been hearing and reading both in the past and recently.  

Thank you
2018-5-30
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DJI Natalia
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Mark The Droner Posted at 2018-5-30 13:34
DJI Natalia -

is this for all DJI Lipos?  Or is this for the P3 lipos?  

This is for Phantom 3 and 4 Series.

https://dl.djicdn.com/downloads/ ... y+Guidelines+En.pdf
2018-5-30
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KedDK
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Denmark
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DJI Natalia Posted at 2018-5-30 13:15
That could be one of the reasons why the battery life dropped to 80-90%. The recommended discharging rate is 10%. Moving forward, just simply the battery maintenance and storage that I provided in order for you to keep the battery life.

"The recommended discharging rate is 10%."
Sorry to correct you but no that is not the case, please look on the the very last line of your own reply in #2 and then hold that against this instruction that is to be found in the manual of both P4P and P3P.



Strange enough, i just can't find the "every 20th cycle discharge" instruction anywhere, i know it was there recently somewhere.
2018-5-30
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RedHotPoker
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Canada
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DJI recommended deep cycling intelligent flight packs for several years.
Now you say it may reduce battery life.

Is that why Battery Life was removed from iOS Go app battery info?

I presume since DJI joined forces with APPLE, that the predominant number of drone pilots here are using iOS devices.

Go figure. Now, Does it add up?


RedHotPoker
2018-5-30
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JackCarter
Croatia
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Just chacked battery levels after this ( first ) deep cycle I've done - around 4300 mAh and 17 V. Original specs were 4480 mAh and 15.2 V. Does thal look normal after some 20 cycles ?
2018-5-31
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solentlife
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This subject does the rounds and still gets the prize for confusion.

1. Deep discharge of any LiPo based battery cell is BAD NEWS.
2. The higher the discharge rate used to get to that deep discharge increases the potential damage that could be inflicted.
3. Damage to LiPo cell is irreparable, it is permanent.

So why the DJI text in manuals to deep discharge after 20 cycles ? This is an old instruction that DJI have failed to modify or re-write manual to be more current.
The Deep Discharge does NOT recover or repair LiPo cells ... that's impossible. BUT what it can do is reset the board counter. Successive discharges in flight of the battery and recharging can lead to the boards chip getting out of step with battery actual condition.
Deep discharge / recharge fully can then  recalibrate the chips reading of battery level.

If you look at any other LiPo use such as normal RC models - you will not see Deep Discharge used ... but of course there is no control board on front of the battery as with DJI. It still does not change this fact though.

To the OP ... I would suggest doing a few cycles like this :

Before connecting charger - switch on battery. Then connect charger. Let it charge up fully (lights stop flashing and go out).

Fly the battery as usual ... (note the votage / % levels displayed in GO).

Again switch on battery - connect charger - charge fully ...

Fly the battery as usual ... (note the votage / % levels displayed in GO).

You may observe a better % figure basically because :

1. Switching on battery before connecting charger bypasses part of the charge controller and I have observed 100% charge results instead of the 99% when charged without switching on first.
2. The Control board Chip my benefit from this and show better results overall.

BUT with regard to Life Display ... that is a matter that basically cannot be altered and will be whatever the board interprets from its recordings.

Last point ...... The battery LED's are 25% increment as full steady on. 12.5% increment when flashing. They are really only a rough indicator - reference should be made to telemetry indications in GO ..

Nigel
2018-5-31
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JackCarter
Croatia
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Thank you, Nigel :-)
I can only hope DJI designed and made their batteries foolproof enought to be able to withstand one deep discharge. Be as it may, from now on I will charge them as usual - fly to some 30 %, and charge to 100 if I plan to fly within next 24 hours. If not, charge up to 60 %, and store it.
I read about switching on the battery before charging when battery is some 95 % full ( so, before the top up ). I will switch it on before charging in any case, it may help.
Have you got any info about life expectancy ? Battery i mentioned was charged 20 times only so far, I would expect at least some 100 cycles...


2018-5-31
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KedDK
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Denmark
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Don't trust the %, keep an eye on the cell voltages, the % is what the board think and can differ from the actual cell state.
2018-5-31
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Mark The Droner
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KedDK Posted at 2018-5-30 22:46
...
Sorry to correct you but no that is not the case, please look on the the very last line of your own reply in #2 and then hold that against this instruction that is to be found in the manual of both P4P and P3P. ...

Thanks for posting this.  I actually wasn't aware that the phrase "below 8%" was added to the manual.

It's hard to keep all this straight.  

Re the P3 manual, I downloaded a copy last winter and it's the same as the one there now.  It supposedly hasn't been revised since July 2017.

Some history:

The P2 batteries deep discharge was to be "below 8%" as specifically written in the manual.  Below 8%, of course, means not 8%.  It means 7% or 6% or 5%, etc.

When the P3 came out, the deep discharge language changed to say "8%."  The word "below" was gone.  There was some discussion on this in the forums.  Was it supposed to be "below 8%" or "to 8%?"  Maybe they left "below" out by mistake?  Nobody was sure.  

Then, one day, the whole percentage thing disappeared.  In fact, its removal seemed to be implying that the P3 battery should not be deep discharged at all.  This jived with many who had claimed this all along - saying a deep discharge can damage the battery.  

Now the "8%" thing is back.  Except they added the word "below" which wasn't there in the original P3 manual.  

Except, the admin is now telling us it actually "is 10%."  Which is not below 10% or 9% or 8%.  

Confused yet?  Read on.  

There is also language in the battery safety guide warning us NOT to "over-discharge" the battery because it can lead to permanent damage.  But it doesn't explain what an over-discharge is.

And yet, the manual states that the battery has an "over-discharge" safety function where the battery will shut off if the voltage reaches 12V.   It's obvious to the veterans on this site that this is due to the fact that the battery will shut itself off if any individual cell drops below 3.0v.  And that is any time, including the time while the aircraft is airborne.  This is all for the good of the battery, because it's very important not to allow the battery to become damaged (the well-being of the aircraft is secondary, apparently).

So if this is true, then how is it possible for us to over-discharge a battery?  

Should we be concerned about over discharging a battery?

Should we deep-discharge to no lower than 10%?

Should we deep-discharge to below 8%?

Should we deep-discharge until the battery shuts off?  

It's all very confusing, and the fact that they keep changing the specifics and also reiterating facts that are contrary to both the aircraft manual and the battery safety guide makes it even more confusing.  And the fact that they periodically change the language of both the manual and the battery safety guidelines doesn't help either.

So what do we do?  

Personally I feel I have no choice but to rely on my own experience, and that is, not to deliberately discharge at all unless there is a solid reason (such as badly unbalanced cells).


2018-5-31
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JackCarter
Croatia
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@ Mark
I tend to agree... perhaps the whole thing about the battries it gone overcomplicated.
If I was writing manual I'd state something like - In usual circumstances one can expect battery to last some xx hours of flying. If one decides to land at 30 % that means some 15 min in the air per flight, ergo you get yy flights, given the battery life expectancy which is xy number of charges. Do not leave battery fully charged, nor empty. Simple as that...

It amazes me it's so hard to get relieble info re. life expectancy. I am sure DJI does some serious testing and they know typical values, they must have flown thousands of drones and have milions of flighthours on the clock. Let's put it this way - when you buy a car they tell you that engine should work fine up to 150000 km, it's not a rocket sciance.
2018-5-31
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KedDK
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Flight distance : 1133038 ft
Denmark
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JackCarter Posted at 2018-5-31 04:19
@ Mark
I tend to agree... perhaps the whole thing about the battries it gone overcomplicated.
If I was writing manual I'd state something like - In usual circumstances one can expect battery to last some xx hours of flying. If one decides to land at 30 % that means some 15 min in the air per flight, ergo you get yy flights, given the battery life expectancy which is xy number of charges. Do not leave battery fully charged, nor empty. Simple as that...

"sure DJI does some serious testing and they know typical values,"
I think you're right, that is why they only offer a 6 months or 200 times charge what ever comes first warranty on the batteries.
2018-5-31
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JackCarter
Croatia
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KedDK Posted at 2018-5-31 08:50
"sure DJI does some serious testing and they know typical values,"
I think you're right, that is why they only offer a 6 months or 200 times charge what ever comes first warranty on the batteries.

It is common for batteries to come with 6 months warranty ( I gues it's same with mobile phone batteries ).
That aside, I would expect a bit more info from manufacturer. I know that life expectancy differ from case to case, but am still waiting for someone to say something along the lines of - I've used the battery for a year, did x number of flights and now it is in that condition.
2018-5-31
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solentlife
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I had a long series of communications with DJI Tech about battery life.

I have LiPo's for many different uses and have a reasonable understanding of their use and maintenance. I certainly do not claim to be expert at it, but I seem to be able to keep batterys useable for significant time - longer than manufacturers claim !

My biggest query was on the old claim of 200 cycles and then battery is ZERO life and some claimed it would shut down. This is absurd as a LiPo should give you 2 - 3x that unless abused. A good battery should even run to 1000 cycles is treated well.

DJI could not agree .. I had 3 different Techs reply to me .. passed one to another as my questioning got deeper and more detailed. First of all I was told that the battery control board would basically quit at 200 cycles and regardless of cell condition - that was it. Next guy said that was rubbish and that the battery will continue to work past the 200 cycles but he ruined his reply by then saying the board cycle count is not incremental. Final guy then threw both previous to the wind and said Cycle determination  is incremental (which is what I observed .. only a deep to full charge give a 1 advance in cycle, a 50% charge gives a partial increment only) ... and he said that the 200 cycle was only an indicator.

There were questions they never even attempted to answer ... Does the battery control board actually balance the cells ? My observations indicate no, the board shuts off before balancing can be completed. When does the balancing supposed to action ? Observation again shows that no balancing at all at lower levels (which would be strange if it did as no LiPo charger does that - only dedicated balancer units can do it as user selects balance only function at whatever point cells are at - and at full charge level where balance chargers change to balancing mode - the battery board shuts off because it detects full voltage total !

Very poor show by DJI Tech ... not even they could agree 'inhouse' ... so not much chance of us the users agreeing !!

I know my observations do not agree with some others claims. Fine - I'm happy with what I observed, I'm happy to base my use and maintenance on that. Same as others base on theirs.

There is one item I do not agree with as I see it as a waste of time :

If you are not going to use your battery for some time ... charge to 50 - 60%.

Why ? If you are talking a week before you use again ... then of you land at 30% or above - that's fine to store. No need to top up anything. Storage level of LiPo runs from 3.7V up to 3.85V. Multiply by 4 ... that's 14.8V up to 15.4V ...

If you are expecting battery to stand for weeks or months ... then FULLY charge and store .. because after x days - the auto discharge routine will kick in and bring battery down to DJI set level for storage ... BUT note that discharge does NOT stop there .. it just slows down and continues until it hits rock bottom 12V and then goes into Hibernation mode.

Nigel
2018-5-31
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JackCarter
Croatia
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Thank you for in-depth answer, and sharing your experience.
I did one flight after doing deep discharge ( to 8 % ), and at the start of the flight it gave me some 19 - 20 min. Flew it for 15 min, and got it down to 30 % - which is within typical values.
So, it seems - so far so good.
2018-6-1
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