???Question About Phantom 3 LiPo Battery Balance Charging/Discharging???

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Greetings everyone. I'm new to drones, having been an electric RC airplane pilot for some time. This weekend I picked up a Phantom 3 Standard and several battery packs, and I'm puzzled by the seeming lack of concern regarding balancing the charge in the individual cells in the intelligent battery pack. I own two balancing chargers/dischargers for my RC plane battery packs, but I don't see any online discussions regarding the need to balance the charge in the cells for the Phantom battery packs. Nor do I see anything (cables, etc.) domestically which would allow me to charge the intelligent battery packs with my balancing chargers (a few cable sets from China that are meant to work with a B6/B6AC charger). Am I missing something? Is that what makes these batteries "intelligent"? They don't need a separate balance charger?
 

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The battery cells will balance themselves when you charge the batteries with the included battery charger. By default, the batteries will start to auto discharge down to 65% after 10 days. It can take an additional 2-3 days to complete that discharge process. If you press the button on the battery, that 10-day counter will be reset. If you'd like to reduce the 10-day wait, you can change that setting in the "Aircraft Battery" section of DJI GO. You'll need to update that setting for each battery while your Phantom is connected to DJI GO.
 
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You got it- the battery contains a balance charger. There are bleed resistors on the cell taps and it works the same as your balance charges. Less fiddling and foolproof.

Discharge is automatic with time to commence adjustable from 1 to 10 days (setting in DJI GO app).
 
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Hi San Diego .... welcome to the world of DJI batterys ... and some of the myths surrounding them.

The DJI Phantom battery is a 4S High Voltage LiPo pack which has been set-up with a charge controller board. The 'Intelligent' bit.
It has basically three jobs to do :

1. To convert the dumb brick 17.4V power supply they give you as 'charger' into charge to the LiPo.
2. To action auto-storage discharge at time set by you or the default 10 days.
3. To provide the telemetry data feedback to your App about voltage etc.

The point about balance is a controversial one in fact as myself and a number of others have tried to determine when the balancing takes place but so far have not succeeded in identifying it.
The problem comes because the LiPo is only providing the two main total voltage points to us and the balance tap is hidden away inside. Even the smaller data points are only two contacts.
The charging actually cuts of based on total voltage as far as we can tell. This has resulted as we found with still unbalanced cells on termination. Luckily it does appear that max voltage as per HV is observed at 4.35V per cell. But not all cells will reach that unless pack is in VG condition.
It has been claimed that deep discharge balances out cells - but that has been disproved by us repeatedly and again unfortunately the control board seems to act on total voltage not individual cells. It has been observed for a cell to dip below what we would consider a safe voltage while another has stayed high. The total voltage then bing seen as correct.

Basically at end of day - charging of the DJI battery is a DJI controlled matter having removed User control of cells.

Charger to use : In fact there are adaptor leads on eBay and various that will allow you to use a standard LiPO charger on LiHV setting ... 4S ... charge mode only. Basically being a two lead connection and no need for balance lead. I prefer this to the DJI charger because I have on screen display of everything going on ... volts, amps, mAh in etc. No matter what you do with any charger - you will not be able to force balance of cells.

As to discharge - you can buy Transfer dischargers on eBay that plug into the battery main contacts and then provide power through USB socket to charge mobile phones, LED lamps etc. They are switchable either storage level or deep discharge. The other discharge is of course auto-setting when battery is idle.
DJI talk about flying or powering the model to do it - but finally even DJI are not promoting the deep discharge myth any more.

There are some reports that the batterys reach 200 cycles and then may stop working. Even DJI Tech will not answer this ... I have 3 different answers from them. What has been found is that the cycle count is not just 1 for each time you charge. It appears incremental and we expect you could see 400 - 500 charges before battery replacement. But as we found - this seems to only apply if you use DJi Go App.

At present there is contention about use of 3rd party batterys ... some work ... some apparently don't. It is suggested that DJI even have included code in FW to block use of some 3rd party batterys. The best advice here IN MY OPINION is to find another owner and what brand / supply of batterys he uses ... because there are good 3rd party batterys despite people trying to report otherwise.

Finally - myself and a number of others are investigating the use of 3rd party replacement cells in the DJI case to reduce the high costs of these units. Initial test indicated that the board basically shut down on replacing the battery pack - but resetting of board is possible as long as it does not shut down. This is ongoing. The second problem here is the physical dimension of the pack itself. It is shorter than a typical HV LiPo and so trying to identify source of cells.

Personally I would have preferred if the control board could have been part of the model and we left to use over counter LiPo's .... but DJI decided to go another route.

There are others will take ,my post above and argue with it .. that's their PoV ... I am only passing on what has been found by my and others investigation and dismantling of DJI packs.

Welcome to the world of Phantoms ...

Nigel
 
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Hi Nigel (or others), do you know if the battery would self-protect from over-discharge? From what I read, it seems it would not: people are saying that the battery would sacrifice itself and drain beyond safe levels in order to keep the AC up in the air, rather than shutting down and making the AC fall from the sky.
I personally use a home-made discharger (two 24V 50W halogen bulbs in series) in those situations where I fully charge a pack but end up not using it, and I do it monitoring everything carefully, with a Voltage/Amp meter in-line, but I'm curious to know if the battery would eventually shut down to protect itself, or if it would continue to go until irreparably damaged (although I have resuscitated over-discharged LiPos in the past, so in some cases they can still be brought back to life).
 
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Hi 120CCPM :

The system has a series of Battery levels that initiate commands.

If you look at the power line below the main title bar on your screen ... you see the green line ... yellow ... red. There are also small letters on the line ... the H one moves dependent on distance from HOME.

OK - you take off ... the Go app monitors the battery level. You have set via Go the warning level and Critical levels of battery ... ie 30% and 10% or whatever.

When the voltage gets to the H figure - it will initiate RTH as it is the calculated power required to get back home and land. Note it does not account for wind. Do not use it as a standard RTH !!
If you cancel this RTH and continue to fly you then pass to critical and then the model will automatically land at the location it is. You cannot fly home.

The model DOES NOT stay in the air infinitum ... it lands out before complete depletion of battery.

Nigel
 
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Hi Nigel, there's actually two parts of my question.
The first was a bit silly, I reckon, as the AC is designed to land itself, and I assume that even if you set the Critically Low Battery Warning to its minimum in DJI GO, it will not drain the battery beyond safe levels (and the AC will definitely not fall from the sky).
The second part still stand, un-answered: does the intelligent battery itself has built-in low-voltage protection, that would eventually cut the power to protect the cells? Say you manually discharge it by connecting it straight to a load, will it shut-down at some point? As I said, I manually discharge only when strictly necessary, and under close supervision, so my question was more of a curiosity than anything else... no real need to know (and hopefully I will never find out the hard way).
 
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Thanks a million Nigel for the in-depth discussion on the intelligent battery, charging, discharging, etc. It does seem that in the interest of simplification for the average user, the "intelligent" battery may be a compromise between simplicity and best practices.
 
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I believe the controller has a limit at approx 8 - 10% and shuts off. The board has been now shown to be a Charge controller and Telemetry board only ... some of the supposed functions have turned out to be myths ...

The manual talks about this level and deep discharging ... which is actually misleading because DJI no longer in their Battery Manual advise deep discharge. But it remains in the Owners General manual ... probably because no-ones bothered to update it.

As you well know deep discharge of LiPo unless you can control EACH individual cell is a risk to damage one or more cells by over-discharge. Plus of course it does nothing for recovery or health of a pack.

Nigel
 
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For anyone interested - myself and another have discussed testing of plain power input to the P3 without the board and with board separately installed.

The interesting fact is that it is actually not even necessary to use HV LiPo - standard 4S could be used as the HV only results in power advantage in approx first 10% of use - then it literally performs same as a standard LiPo ...

You can prove this yourself by having Voltage displayed ... the AC is still flying at well below standard LiPo voltage. and uses same range. Expect maybe 19 - 20mins instead of 23 - 25mins flight.

Nigel
 
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For anyone interested - myself and another have discussed testing of plain power input to the P3 without the board and with board separately installed.

The interesting fact is that it is actually not even necessary to use HV LiPo - standard 4S could be used as the HV only results in power advantage in approx first 10% of use - then it literally performs same as a standard LiPo ...

You can prove this yourself by having Voltage displayed ... the AC is still flying at well below standard LiPo voltage. and uses same range. Expect maybe 19 - 20mins instead of 23 - 25mins flight.

Nigel
If you use standard V LiPO packs will you charge them with a traditional charger? The DJI charge board would attempt to charge the cells to HV LiPO terminal voltage. This might be where your external smart charger as the supply approach might prove very effective, potentially limiting the terminal charge voltage if used in standard LiPO setting.
 
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Of course there is no way you could use the DJI charge method. The DJI Charge board sets the HV LiPo max at 4.35V ... where standard LiPo is 4.20V ...

(4.35V is the industry noted maximum voltage level any LiPo can achieve before serious damage or 'event' may occur. Yes you can push a standard LiPo to 4.35V - but you better be prepared for shortened life, possible swelling and even flames. But a standard LiPo is capable of greater than 4.20V. BUT PLEASE DONT DO IT !!)

If its possible to connect standard LiPo - then we get advantages :

a) Use of common and reliable LiPo chargers
b) Higher charge rates shortening charge times
c) True balancing and interrogation of packs during charge / discharge etc.
d) User controlled individual cell and storage control

and finally a budget price of LiPo that beats DJI packs by a very large margin.

For one single disadvantage - slightly reduced flight time.

I for one can accept that because I rarely fly longer than 19mins anyway. I only do that length when testing FW / Go / Litchi.

I am always open to suggestions of test or maybe ideas that could work with our systems.
If someone has already tried connecting plain LiPo for example - the info from that would be monumental. But I do ask that information be actually observed.
I do not believe I am alone in wanting solutions. Even some who 'pour scorn' on my work - surely even they would 'secretly' use what is found...

Nigel
 
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4 years later... i can confirm that the battery does not self balance. I have one pack and 1 cell is lower voltage than the others. After charging, 3 cells are at 4.35V and last Cell is 4.17V. For me this seems very strange, why does it not balance the cells? Do you know any way I could charge externally the forth cell in order to bring it to the same level as the others?Will this fix the pack?
 

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