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Completely Drain Batteries?
4304 28 2017-12-31
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Steve2017Newbie
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It seems I read somewhere you are supposed to run your batteries down completely once in a while.  Is this true?   If this is needed do you just leave it on until it's fully drained? I have a Spark and a Phanom 3 4K
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2017-12-31
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Mark The Droner
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Completely draining a Lipo is never a good idea that I've ever heard.

You seem to be referring to a deep discharge which would be to first fully charge, then discharge down to something like 5-8%, then fully charge.  The consensus these days is it's not a good idea except perhaps in extreme cases.  
2017-12-31
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Dirty Bird
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DJI recommends running them down to <8% once every 20 flights.  Does it make a difference?  I'm not sure as I often run my batteries down to 10-15% in normal flying.  Once in a while I will  let it hover nearby until the battery level drops below 8%.  The process is much quicker if you are flying rather than leaving it setting on a table turned on.  May also be better for the bird as air is moving around the electronics.
2017-12-31
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Labroides
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Dirty Bird Posted at 2017-12-31 15:22
DJI recommends running them down to

DIJ haven't recommended that for a long time.
2017-12-31
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Dirty Bird
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Labroides Posted at 2017-12-31 16:53
DIJ haven't recommended that for a long time.

If true I guess that's what I get for not reading the latest edition of the manual.
2017-12-31
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solentlife
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Dirty Bird Posted at 2017-12-31 17:40
If true I guess that's what I get for not reading the latest edition of the manual.

Unfortunately manuals haven't all been updated !!

But anyway ... if you are 'flying' and running your battery to 8% .............. I have to question your action.

Minimum battery level user can set for Critical Battery which automatically starts Auto Land is 10%. Interesting you say you fly to 8% .... How ?

OK ... after testing a number of DJI and non DJI  batterys - the DJI P3 battery drains to 0% and is actually about 12V .... automatically shuts off. That is 3.0V per cell. That is generally regarded as the absolute lowest you should ever go. Recc'd lowest is 3.3V per cell .... 13.2V total.

DJI batterys are what are termed Lithium HI Voltage Polymer ... (LiHV) ... which rise to 4.35V per cell max. A conventional LiPo is 4.20V per cell at full.
LiHV packs deliver higher power for the first 10% or so of use and then exponentially get to behave same as conventional LiPo ... so the 'Fuel Table' here is accurate enough from about 70% and down ...



Nigel
2018-1-1
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Dirty Bird
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solentlife Posted at 2018-1-1 02:49
Unfortunately manuals haven't all been updated !!

But anyway ... if you are 'flying' and running your battery to 8% .............. I have to question your action.

To keep the aircraft aloft below 10% battery you apply the throttle.  The bird will maintain altitude & she can even climb, though at a reduced rate.  You can hold her in the air all the way until 0% (and beyond) until the voltage drops to shut off level.
2018-1-1
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R&L Aerial
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I usually run then down a couple of times a year. They way I do this is to fly till battery tries to force auto land then I fight it till the battery gets to 5% I then land a recharge. Everything is then good to go....
2018-1-1
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solentlife
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Dirty Bird Posted at 2018-1-1 06:51
To keep the aircraft aloft below 10% battery you apply the throttle.  The bird will maintain altitude & she can even climb, though at a reduced rate.  You can hold her in the air all the way until 0% (and beyond) until the voltage drops to shut off level.

Interesting ...

I can say without question - the P3S will not even start to do that ... I know to my own cost. Once Autoland kicks in ... that's it ... you better be over good spot. That occurs before and locks in at 10%. I have video proving it. No amount of stick wielding made any difference at all. She went into the river ...  Rescued it but she's history.

I now have P3P and I will not be stupid enough to get near that situation again ... so I can only refer to page 13 of the manual which states :

The aircraft will land automatically if the current battery level can only support the aircraft long enough to descend from its current altitude. The user can still use the remote controller to alter the aircrafts orientation during the landing process.

I can only assume that your action is close in and low enough to let the AC use less than 10% to descend etc. 10% is the lowest setting for Critical battery which initiates autoland ...

Still a very dubious and risky practice to get into ... power drain in those low levels is very fast due to low voltage and high amps ... not something to play around with.

Nigel
2018-1-1
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solentlife
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R&L Aerial  Posted at 2018-1-1 06:59
I usually run then down a couple of times a year. They way I do this is to fly till battery tries to force auto land then I fight it till the battery gets to 5% I then land a recharge. Everything is then good to go....

I'm glad I'm not your batterys !!

Honest.

I have possibly over 100 LiPo's including DJI and I would never do that to any of them ... my bank balance would cry !!

Nigel
2018-1-1
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Mark The Droner
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My understanding from reading a couple thousand battery threads is that 0% is not really 0% in the newer Phantoms.  It may have been closer to 0% in the older Phantoms, but not in the newer ones.  I believe it was a post by Gadgetguy in the other site fairly recently.  IIRC, he was saying 0% is actually 3.6 v per cell which we know means the battery still has juice.  And this might begin to explain why the so-called deep discharge percentage has seemingly dropped from 8% in the older Phantoms to 5% in more modern Phantoms, even as DJI doesn't clearly recommend a deep discharge in these modern times... and yet we keep seeing somewhat vague references to a deep discharge in various DJI links...
2018-1-1
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Aardvark
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And DJIs notes say no more than to fully charge and discharge at least once every three months to maintain battery health. I never allow my batteries to go below 10% if discharging.

https://dl.djicdn.com/downloads/ ... y+Guidelines-EN.pdf


2018-1-1
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solentlife
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Complete discharge of DJI battery manually (with latest battery FW) shuts off just before 3.0V .... I did it only a short while ago to see if I could force board to charge at higher rate by having battery as low as possible.

Its actually not easy to see how far down the battery gets unless you have a connector already fitted to register for this split second the voltage. Because its so low - the board shuts off power almost immediately causing contacts to be disconnected.
As you can see from the table I posted earlier ... 10% equates to about 3.6V ....

The reason the table quotes 3.2V as zero - is to tell users not to go that low !! because LiPo's will continue to 0.0V if given opportunity - that's regular LiPo's

Nigel
2018-1-1
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Mark The Droner
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What battery are we talking about?  

What you state contradicts what Gadget Guy posted, but it may be a difference in batteries such as p3 vs p4...
2018-1-1
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solentlife
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I did my tests with P3 batterys .... and I thought this was a P3 section ?
I would not expect P4 to be different cell by cell than P3 ... as a LiPo is a LiPo ...

What GG found I don't know - but what I do know is what I found when doing the test only a few weeks back.

I manually discharged the P3's (I did it with 3 different batterys ... 2 were non DJI with one a DJI) ... all 3 did exactly same. They have latest FW on them as well.

I cannoty confirm what level the AC would take them to as I am not willing to go that route. Manually separate - yes - but not by plugging in to AC.

Nigel
2018-1-1
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Mark The Droner
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Aardvark Posted at 2018-1-1 07:49
And DJIs notes say no more than to fully charge and discharge at least once every three months to maintain battery health. I never allow my batteries to go below 10% if discharging.

https://dl.djicdn.com/downloads/phantom_3_se/20170810/Phantom+3+Intelligent+Flight+Battery+Safety+Guidelines-EN.pdf

Yes - the last page is the relevant bit.  In another thread, this was brought up and DJI Susan stated that the magic number to aim for on the deep discharge is no more than (I believe she meant no less than) 5%.  When I questioned her, she further went on to state that this was only regarding storage ...
2018-1-1
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solentlife
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Mark The Droner Posted at 2018-1-1 08:17
Yes - the last page is the relevant bit.  In another thread, this was brought up and DJI Susan stated that the magic number to aim for on the deep discharge is no more than (I believe she meant no less than) 5%.  When I questioned her, she further went on to state that this was only regarding storage ...

Storage ????

Oh dear !

I hope she was not suggesting storing at 5% ............ can you elaborate more Mark ... as that needs to be qualified before a newbie ends up having to buy a new battery !

Nigel
2018-1-1
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Aardvark
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Mark The Droner Posted at 2018-1-1 08:17
Yes - the last page is the relevant bit.  In another thread, this was brought up and DJI Susan stated that the magic number to aim for on the deep discharge is no more than (I believe she meant no less than) 5%.  When I questioned her, she further went on to state that this was only regarding storage ...

I wonder if it's down to interpretation really, it says to fully charge (normal and expected) then 'discharge' them, to keep them maintained in good working order.

I just make sure my batteries are all used regularly, I've had them 20 months now and as yet have had no problems at all with any of them.

2018-1-1
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solentlife
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Aardvark Posted at 2018-1-1 08:33
I wonder if it's down to interpretation really, it says to fully charge (normal and expected) then 'discharge' them, to keep them maintained in good working order.

I just make sure my batteries are all used regularly, I've had them 20 months now and as yet have had no problems at all with any of them.

That is my PoV as well ... its regular use that keeps them tidy. With a decent flight run amongst that.

I usually fly to about 30 - 35% ... and that is generally regarded as a healthy level for LiPo's ... Occasionally I will fly to lower but I avoid it from being too often.

Nigel
2018-1-1
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Mark The Droner
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A deep discharge is by definition -

Full charge, discharge, full charge

... as stated in post #2

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solentlife
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Mark The Droner Posted at 2018-1-1 08:45
A deep discharge is by definition -

Full charge, discharge, full charge

Don't you mean

Full Cycle is Full Charge ... Full Discharge

Deep discharge just means a discharge to very low level - nothing else ... unless the English Language has been modified ?

Nigel
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Mark The Droner
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Do you have a link?  
2018-1-1
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solentlife
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C'mon Mark .... English Language may have been dessimated by the USA and Bill Gates ... but really ...

Nigel
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Dirty Bird
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solentlife Posted at 2018-1-1 07:15
Interesting ...

I can say without question - the P3S will not even start to do that ... I know to my own cost. Once Autoland kicks in ... that's it ... you better be over good spot. That occurs before and locks in at 10%. I have video proving it. No amount of stick wielding made any difference at all. She went into the river ...  Rescued it but she's history.

I run older firmware but unless there has been a major change all you need to do is apply & maintain throttle & you can hold a P3S in the air until the battery literally shuts down or is unable to spin the motors fast enough to produce lift.  That's how all of my birds work whether they be P3, P4, or Mavic.  This is how I d8scharge down below 8%.  After a flight I just hover nearby until the level drops.
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Mark The Droner
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solentlife Posted at 2018-1-1 09:36
C'mon Mark .... English Language may have been dessimated by the USA and Bill Gates ... but really ...

Nigel

You don't have a link because there is no link.  
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Rstrachan
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(I hate losing my carefully crafted reply when I switch tabs to get quotes & links)

Read your Intelligent Flight Battery info in your User Manual and Safety Guide. Page 21 of the P3A User Manual v1.8 (2017-07-06) explains how to discharge to 8% but, doesn’t explain why or how often. (See below)

fwiw, links to updated User Guides are on the same page you download your aircraft firmware. The 1.8v is the most current for the P3A

As a R/C stadium truck enthusiast, I’ve read lots of forum threads regarding lipo batteries and their maintenance, usage and storage.

One thing to remember about that info? Verified information and thread rot. Verify to the best of your abilities. Thread rot should be self explanatory.

Generally, lithium-polymer batteries should not be discharged below 3v per cell. Most, if not all, newer devices, like the Phantom’s Intelligent Batteries, have a failsafe built in to prevent this. (As confirmed by Solentlife, this is the 10% Critical Battery warning).

Generally, regularly discharging P3 batteries, really any lipo, to the bare minimum can reduce its lifetime. It’s been my experience, in my other devices, that lipos have a longer lifetime if I don’t run them completely down. As an example, my wife’s cell phone is two years old and the battery only lasts 12hrs. She runs her phone dead at least a couple times a week. My cell, same phone, same age, lasts 24hrs. I rarely let my phone get below 50% charge. Extreme example but, it’s a real life one.

Here is a great non biased article for lipo battery health [url= http://batteryuniversity.com/lea ... ium_based_batteries]Prolong Lipo Batteries[/url]

This may explain why DJI says it’s ok to ‘completely’ discharge the P3 batteries every so often: “There is no memory and the battery does not need periodic full discharge cycles to prolong life. The exception may be a periodic calibration of the fuel gauge on a smart battery or intelligent device.” Battery Calibration


@solentlife, I’d like a copy of that spreadsheet or web form you calculated voltage based on percentage. Please and thank you.
2018-1-1
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Rstrachan
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Link got messsed up

Prolong lipo battery health
2018-1-1
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Steve2017Newbie
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Rstrachan Posted at 2018-1-1 13:11
(I hate losing my carefully crafted reply when I switch tabs to get quotes & links)

Read your Intelligent Flight Battery info in your User Manual and Safety Guide. Page 21 of the P3A User Manual v1.8 (2017-07-06) explains how to discharge to 8% but, doesn’t explain why or how often. (See below)

wow thank you very much
2018-1-2
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solentlife
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Rstrachan Posted at 2018-1-1 13:11
(I hate losing my carefully crafted reply when I switch tabs to get quotes & links)

Read your Intelligent Flight Battery info in your User Manual and Safety Guide. Page 21 of the P3A User Manual v1.8 (2017-07-06) explains how to discharge to 8% but, doesn’t explain why or how often. (See below)

Many thanks ....

I will see if I can drag it out of archive ... I have changed PC about 5x over last year !!

Mark has been dogging me as part of his 'fun' about links ... the jokes just wearing thin.

One of the biggest problems here - is that people get hooked into this idea that DJI look after their batterys totally ... that there's nothing else in the world.

As a dedicated user of LiPo's / LiIons / LiFe / LiFePo ... as example in many forms and models - I try to pass on info about them. I have bench gear to test them ... I have set-ups to discharge / charge ... to even individualise cells in multi-packs ...
I own now and ran laboratories for many  years for Multi-National Companys so I am well aware of lab grade gear ...
A close friend who went to school with me became a senior tech with Mallory - THE Battery people !!

Nigel
2018-1-2
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