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Intelligent Battery Power System Design
415713 415713 2016-1-19
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DJI-Tim
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In a previous post, I discussed how our intelligent batteries work and how they differ from traditional batteries. Dynamic power management is one key traits of intelligent batteries that makes them suitable for use with UAVs. As such, this post will talk about the basic design of intelligent battery’s power management system.
Below is a diagram detailing how power runs through an intelligent battery:

diagram.PNG
Power Outlet:
Alternating current (AC) house hold power has a voltage of 220V and a frequency of 50Hz in Shenzhen, China (where DJI HQ is located),though the exact numbers differ in different parts of the world. However, we cannot charge the battery by using 220V AC directly, so we need to adjust the power and then charge battery. So we need an…

Adapter:
2.jpg
You probably know the adapter  as the “big black box”on your power adapter, as pictured above. A adapter takes the AC current from your house’s power supply and converts it to an appropriate DC current.

For example, the Inspire 1’s battery needs a 26.3V DC to charge. 26.3V DC will be output by the power adapter after the AC current runs through the copper coils of the transformer. A few other parts called the rectifier, filter and regulator make sure your signal comes out polarized and evenly.

Relay:
Now that the charger outputs the correct voltage, we can charge the battery directly. But to gain intelligence, we can install a relay to control when to charge the battery and when not to charge it. Take a look at the diagram below:
Simply put, it is controls when to charge and discharge the battery.
Load Management:
   Apart from the power adapter’s relay, the battery contains a number of other “load modules” that control the flow of electricity. The most basic load is the motor. In a circuit, several load devices are employed, such as resistors, inductors, capacitors, and detection sensors.
Battery Controller Chip:
The controller chip is the brain of the intelligent battery’s power management system. The controller can detect the voltage of a lithium battery and then manage the battery’s charging and discharging by controlling a relay switch. It has several basic functions:
1. It can control the battery to charge or discharge by controlling the relay.
2. It can detect the battery voltage, current, remaining power level and other parameters in real-time when the battery is powered on.
3. It can wirelessly transmit battery information to the ground system and receive the instructions from the ground system.
3.jpg
Some intelligent batteries have other functions, such as temperature detection protection, energy calculation, battery storage data,charging algorithms and over current circuit protection. Since battery technology is always improving, more and more control chip functions will be developed and implemented.
Wireless Data Transmission Module:
When power system information is collected by the control chip, a battery data signal will be transmitted to the aircraft and then to the RC through the wireless transmission module in the aircraft
RC will also send some instructions to the controller chip and adjust the battery discharging by controlling the relay switch, which can detect and control the aircraft in real-time.
The wireless transmission module can transmit data through the antenna. Below is a picture of the Phantom 2’s antenna:
4.png
The battery is placed in the battery socket on the aircraft. The two smaller pins on the left are used to transmit data. Two flat ports on the right are positive and negative pins used to charge the battery.

We can see two yellowish brown cables in the figure,which come from the battery’s signal port and transmit data signals to the circuit board directly
5.png
Finally, data can be transmitted to the RC by the signal antenna.
6.png
In this last section, for comparison, let’s talk about atraditional lithium battery.
The battery has multiple cells, but cables are connected to the port of each cell individually. It is not intelligent!

When the battery is charging, the charger displays the charging conditions, including voltage, amperage and charging time
7.jpg

Also,the voltage meter needs to be used to prevent the battery  from over discharging.
8.jpg

Intelligent batteries have lots of powerful functionality, and I believe they will become cheaper and more powerful over time. Let’s look forward to more progress!


2016-1-19
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luigi.tarascio
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It seems to be a very good idea except that a 30 euros battery and a 5 euros electronics become a 150 euros battery.
2016-1-20
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kvamens
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luigi.tarascio Posted at 2016-1-20 12:07
It seems to be a very good idea except that a 30 euros battery and a 5 euros electronics become a 15 ...

That,s why they call it bussiness
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FlyFocal Aerial
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Very informative, thank you!

FlyFocal
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kvamens Posted at 2016-1-20 16:20
That,s why they call it bussiness

At 428% price increment. We need more competitors IMHO.
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kvamens
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luigi.tarascio Posted at 2016-1-20 17:22
At 428% price increment. We need more competitors IMHO.

Agree to that
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christopherglen
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Can we have the intelligent battery force an auto landing instead of cutting off power and forcing a crash?
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Hendo
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Thanks Tim, a useful explanation. I have a question regarding power supplies. I have a P3A with 57W power supply. I also have a desktop lab power supply that I can adjust voltage and current 0-30V/0-10A. Can I set the desktop supply to 17.5V with current limited to max 6A and use this to charge the P3 battery? The objective is to get a faster charge.
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dji-p3p1
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Hendo Posted at 2016-1-21 09:29
Thanks Tim, a useful explanation. I have a question regarding power supplies. I have a P3A with 57W  ...

I believe the Black Adapter is simply a PSU that outputs 17.5V to a max 5.7 amps.
So for a P3, a Bench-top PSU adjusted to output 17.5V and limited to 5.7A* (as per spec of the 100W Charger) should work fine for a fast charge. Just make absolutly sure that polarity is observed.

* Charging/Monitoring circuitry is in the battery itself, so I suspect that the battery will just draw the number of amps (load) it requires at various stages of charging if you exceed 5.7A. The limit is just there for safety.  - However DO NOT at any time exceed 17.5Volts.
I have seen a battery happly charging with a PSU set at 17.5V and capable of supplying 12A. Full charge time is still around 1 hr - but im not sure if you'll void any warranties.

DJI-Tim, Thats a Nice article. Thanks.




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DJI-Tim
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luigi.tarascio Posted at 2016-1-20 19:07
It seems to be a very good idea except that a 30 euros battery and a 5 euros electronics become a 15 ...

they selling iPhone for 649 $, but the cost of producing is around 200 usd...
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DJI-Tim
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christopherglen Posted at 2016-1-21 05:00
Can we have the intelligent battery force an auto landing instead of cutting off power and forcing a ...

we do have this feature since 3 years ago critical low battery autolanding
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DJI-Tim
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Hendo Posted at 2016-1-21 06:29
Thanks Tim, a useful explanation. I have a question regarding power supplies. I have a P3A with 57W  ...

in theory it sounds ok, but if something happens to the battery after charging with 3rd party power supply  warranty will not cover the damage. so i'd still wait or buy 100W charger
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I would ONLY buy a 3rd party Battery, if DJI had a system like Apple and there MiFi certification. If it wasn't approved by DJI themselves, I wouldn't even look at another manufactures battery. Too many LiPo hove board batteries going up in flames  . . .
2016-1-20
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RichJ53
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Hello Tim,

Thank you for the basic explanation and flow chart diagram of the Intelligent battery.  This is a welcomed thread for us to comment some things. The technology is nice to have especially and when everything is working as designed... great information at our fingertips. But not so much when things are not working..  some of us almost to the degree of disaster will strike us down.

Suggestions for change please:
Remove Auto discharge feature
1) We have had some battery drops for various reasons. Paul and I have been requesting DJI to make the auto discharge feature and option that can be turned off on the App if not needed.
Power lead adaptor option
2) Can DJI provide us with an adaptor to connect to the battery that would allow us to override the Intelligent circuitry? Some batteries are dropping below the safe cut-off voltage and the stock battery charging system will not revive the battery back to life. I can only assume that if we could circumvent the Intelligent system enough to get the battery cells to the proper level again the battery could be saved.
Adaptor to allow users to Store or deep cycle the batteries
3) Provide us with a 50% charging option for storage, deep cycle or manage the batteries without damaging the control circuit etc.

Thanks for your attention and continued support in the forum.

Rich
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DJI-Tim
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RichJ53 Posted at 2016-1-21 13:13
Hello Tim,

Thank you for the basic explanation and flow chart diagram of the Intelligent battery.   ...

Rich
I totally understand your needs and appreciate  your valuable suggestions.
They will be passed to our engineers for future consideration
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dji-p3p1
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RichJ53 Posted at 2016-1-21 16:13
Hello Tim,

Thank you for the basic explanation and flow chart diagram of the Intelligent battery.   ...

Richj53

Good Suggestions..., heres some feedback.

> Remove Auto discharge feature
I Completly Agree with this...but not completly remove it, insted add an option to Disable Auto Discharge.

> Power lead adaptor option.
I Completly Agree with this - I suspect that the batt would require re-tooling/re-design to achieve this.

Adaptor to allow users to Store or deep cycle the batteries
I normally hover the P3 a foot or so above the ground and then land and leave it switched on (props stopped) as the voltage approaches 3.85 volts per cell, which normally corresponds to storage voltage. - so less of a priority to have this functionality. - I really dont like Deep cycling LiPo's as ive always had problems with packs that ive deep cycled in the past.(even when ive been careful)...,id rather stick to regular charging and discharging (never under 3.3V) + storage when required, to maintain a longer cell life and forgo the 2-3 extra minutes provided by deep cycling. (maybe Smart Packs are different?)
2016-1-21
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luigi.tarascio Posted at 2016-1-20 11:22
At 428% price increment. We need more competitors IMHO.

It will come - maybe not quickly, but it will come. Go back about 5 years and price HD flat-screen televisions.

I personally don't think we really need it - at least not at home - but the 4K TV market is slowly taking off. Walmart is already selling 4K televisions in the $500 area. Granted, the quality of the picture produced leaves something to be desired, but it's not just a start - it's a big start.

In some ways, I would like to see "dumber" technology. Particularly in the quad-copters, the name of the game seems to be a single magic board that contains everything. But if you have perhaps even a minor crash, most of us don't begin to possess the necessary tools to effect repairs.

By contrast, if the flight board, ESCs, GPS receiver, etc., were all separate components one could accumulate the necessary parts and keep your bird flying for quite some time. Imagine if the blinkers on your car stopped functioning properly and you discovered you had to replace a computer that controls *all* the lights on the car!

Of course, on the other end of the spectrum, if everything can be put on one board and zillions of them are sold, they can be sold pretty cheaply.

I had my first computer (PC) back in the 70s. They've come an incredibly long way since then.

Art - N4PJ
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2016-1-21
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aburkefl
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DJI-Tim Posted at 2016-1-20 21:47
they selling iPhone for 649 $, but the cost of producing is around 200 usd...

This is not an original idea - the original idea (from my perspective) comes from a guy named Clark Howard. Clark is a "syndicated" show host here in the U.S. He offers tips on finance, tax, electronics and a host of other ideas designed to help people save money and avoid making purchasing mistakes, otherwise known as getting ripped off!

Clark's advice - don't pay $800 for the latest iPhone. Buy a refurbed one from last year for $250. You great the great majority of the technology without the expense of having to own the latest-greatest.

Kind of like someone buying a P2V instead of the P3Pro. You still get a big bang for your buck with the older model.

Regardless, the article Tim produced was very informative and very interesting.

Art - N4PJ
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2016-1-21
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aburkefl
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RichJ53 Posted at 2016-1-21 00:13
Hello Tim,

Thank you for the basic explanation and flow chart diagram of the Intelligent battery.   ...

Hi Rich. Some very good ideas, but I'm lost on option number three. What are you suggesting as a replacement for the semi-automated discharge system that the P3 battery is already using?

I find I can leave my batteries on the shelf in "storage" level for a number of weeks and then bring them back up to full charge when I'm ready to fly.

Could you please elaborate on your Option 3?

Thanks

Art - N4PJ
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2016-1-21
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sotiris.boutsis
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DJI-Tim Posted at 2016-1-21 04:47
they selling iPhone for 649 $, but the cost of producing is around 200 usd...

Still it's about 200% profit against 400% + you are going for. On top of that there are endless alternatives for someone that cannot afford or simply don't want to spend $649 for an iPhone. With the P3 batteries it's a total rip off and monopoly.
2016-1-21
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sotiris.boutsis Posted at 2016-1-22 08:46
Still it's about 200% profit against 400% + you are going for. On top of that there are endless alt ...

> On top of that there are endless alternatives for someone that cannot afford or simply don't want to spend $649 for an iPhone.


Really???.... Put your Money where your mouth is and Please show me ONE Non-Apple alternative that I can Load any App from The Apple App store and Run IOS, has the hardware reliability and the support structure/framework that Apple has in place!

....And its NOT Rip-off!

DJI Have spent possibly Millions of Dollers on Design, Development and Marketing of the P3... So each P3 that you bought should cost a lot more (maybe more then Double) then what you paid for it

But...,  Only DJI, in the current market, have a machine that is capable of what the P3 does in its price-point!
They can reduce the price of the Quad itself, below what other manufacturers can price similar spec of Quads, so they Have to make money on the accessories.

So the price of the Batteries is Not Rip-off... You just pay less for the quad to Balance the price of accessories!

Its called, Being Smart and Staying in Business!...., Whilst still giving the consumer what they want for the price they can afford to pay for it as a basic package.


And....., That's why Ordinary Everyday Earning People like you and me can afford to buy a fantastic machine like the P3.



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aburkefl@gmail. Posted at 2016-1-21 15:09
It will come - maybe not quickly, but it will come. Go back about 5 years and price HD flat-screen ...

you just described a Phantom 2 vision plus..  lol


As far as battery cost I kinda compare it to the home printer market.

sell you a printer for 49 bucks and ink for 25 a pop for years...
p3p at 500 and batteries at 150 a pop for years.

where is the money at?
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DJI-Tim
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Right, a lot of products are like this, i believe this is normal market behavior
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DJI-Tim Posted at 2016-1-20 22:44
Rich
I totally understand your needs and appreciate  your valuable suggestions.
They will be passe ...

Thanks Tim,

who knows we may finally have something that people agree on.  

Rich
2016-1-21
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dji-p3p1 Posted at 2016-1-21 00:18
Richj53

Good Suggestions..., heres some feedback.

I did not explain this very well and I am not sure I am going to do any better this time either.

Because the battery does not give us access to the individual battery cells, if we had an adaptor that could give us the ability to check and measure our batteries... say for proper storage without having to connect to the App or aircraft that would be nice.  I do not want to plug my battery into the aircraft and start up the iPad and remote every time I would like to check the battery condition. Plus this information is not always accurate

When I say deep cycle... this means a way to discharge the battery safely bringing it down to say a storage level (50%) without needing to put the battery inside your aircraft and go fly. Many of us have plenty of batteries that are charged and ready to go. Sometimes we may need to just discharge them for storage and I do not have the time to install and fly all 8 batteries.... We need way to bypass the Intelligent circuit.

Rich

2016-1-21
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DJI-Tim Posted at 2016-1-22 13:51
Right, a lot of products are like this, i believe this is normal market behavior

Correct DJI-Tim,

I agree with you.!  Many Products are priced in this way. There is nothing wrong with that. In fact both the consumer and Manufacturer benefit.

Consumers get Base Products at a Good Price-point that we can afford and Manufacturers can do good business on accessories. - That is Normal Business practise.


Getting Back to Topic - Your Explanation on Smart Battery's is very informative.

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aburkefl@gmail. Posted at 2016-1-21 12:16
Hi Rich. Some very good ideas, but I'm lost on option number three. What are you suggesting as a r ...


You are right, I didn't do a very good job.       I promise I have not been drinking  

check my other explanation above and see if that is better

Simple, we need a way to access the battery information without connecting up to the iPad etc. Or if we want to check the cells by connecting it to a VU meter etc.


Rich
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dji-p3p1 Posted at 2016-1-22 01:41
> On top of that there are endless alternatives for someone that cannot afford or simply don't want ...

It is called Android idiot and is doing exactly the same things if not more.
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sotiris.boutsis Posted at 2016-1-22 19:36
It is called Android idiot and is doing exactly the same things if not more.

Easy Tiger! - Calling other people insults just reflects poorly on your own intelligence!


> It is called Android.

Really? - I thought you were talking about the price of an iPhone - Contradicting ourself now, are we?

Please Don't Compare Apples to Lemons!

....So how many times in the last month has your Android Lemon decided to reboot/hang without notice? (Do us a favour, be smart & dont answer that, Its rhetorical - I think we all know the answer).  Besides your antiphon is expected to be deficit in the relevant perspicacity to perpetuate this colloquium.

Let me put this in plain simple English so that you can understand:
    - Apples are priced at around $3 per kg because thay are Apples.
    - Lemons are Priced at around $1 per kg because they are Lemons.
One cannot walk into an Apple Store and pick up an Apple and expect to pay a Lemons price.

So Like you said, they "is doing exactly the same things"....., I think Not!

Based on my current platform base and requirement for reliability, I wouldn't yet get an Android phone if they were giving them away for Free!
Besides I dont have the appitite for Lemons anyway!

Anyway, as they say.., Never argue with a.............,  Getting back to topic - Where were we?....., Ah!, Yes..,  Intelligent Batteries.. At least they are smart enough not to insult anybody!  




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DJI-Tim Posted at 2016-1-21 10:51
we do have this feature since 3 years ago critical low battery autolanding

I am referring to the cold battery - drones falling out of the sky that the firmware from last month was to address.  The battery should never shut off - no matter what - if the drone is in flight.  Everyone is better off destroying a $150 battery, then randomly dropping a $1000+ drone out of the sky.  
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christopherglen Posted at 2016-1-22 09:15
I am referring to the cold battery - drones falling out of the sky that the firmware from last mon ...

This, this exactly.  I would much rather land and find out the battery is toast then the aircraft fall out of sky due to discharging battery.
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Tim, this is really cool.  Thank you!
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RichJ53 Posted at 2016-1-22 15:29
I did not explain this very well and I am not sure I am going to do any better this time either.

...

Rich,

I got it... I think you mean like the JST connector on a Normal Lipo Pack where you have direct electrical access to every individual cell.

If so, then I agree that this would be immensely useful. - In fact when I got my new P3 one of the first things I did was to look for that type of adapter on the Battery Pack. (but obviously didn't find it).

Ok - Now I understand what you mean by Cycle. - Yes with 8 packs, one would probably be spending the best part of >80 Minutes to properly bring all full packs to Storage by flying the quad.

One problem I can foresee by bi-passing the intelligent circuitry, the "brain"in the pack will not be aware of the state of the pack if a charge/discharge cycle has occurred through a direct adapter.
i.e. Initial pack storage level is say 98%. We then discharge it directly to say 60% for storage purposes. When the pack is used on the P3 and "intelligence" is  switched on, the Smart Circuit (Not smart any-more) thinks that the pack is still at 98% giving an erroneous reading to the Go App - The obvious way around this is to fully charge a pack before use so the Smarts will know when the battery is full - But then all that is dependent on very careful battery management and accurate battery state judgement by the end user. - And as we may have noticed, there can be some here that find a little better judgement a big challenge.
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kirk2579@aol.co Posted at 2016-1-21 20:47
you just described a Phantom 2 vision plus..  lol

Apparently the same place as those stinkin' razor blades!
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RichJ53 Posted at 2016-1-21 23:29
I did not explain this very well and I am not sure I am going to do any better this time either.

...

Okay. I got it. That makes perfect sense - at least to me!

One of my other quads is a Chroma.  They have a "cartridge" style battery somewhat like the IFB in the Phantom - but it certainly isn't "smart!" Initially, they sold the battery with no capability to self-discharge or hook to a charger that provided "storage" settings.

Fortunately, not long after they hit the market, they came out with an adapter that lets you fit their battery to a "standard" LiPo charger and select "storage" settings.

That *would* be truly handy if you could also do that with the Phantom battery. Instead of constantly having to futz with the self-discharge settings.

Art - N4PJ
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Well I HAVE HAD MY PHANTOM 3 Standard for 4 days and it is unusable. The reason is a good battery can not be used because the intelligent system. Is not working properly. This really is technical progress! I worked in automated industrial systems for 50 years and all are designs could allow for safe manual overrides which apparently has not been considered.
Dave
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dji-p3p1 Posted at 2016-1-22 16:56
Rich,

I got it... I think you mean like the JST connector on a Normal Lipo Pack where you have dir ...

Yes I think we are all on the same page now.

I hope DJI can come up with something to help us out.

For me the first thing that would be great (IMO) is to have the DJI Go App, add the ability to disable the auto discharge feature!

Rich
2016-1-22
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aburkefl@gmail. Posted at 2016-1-22 17:31
Okay. I got it. That makes perfect sense - at least to me!

One of my other quads is a Chroma.  Th ...

HI Art,

I hope they can come up with something to help. This is exactly what I was talking about. Even if you cant connect it to a standard LiPo charger (because of the Intelligent circuit), just be able to access the battery with VO meter or to discharge.

Rich
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RichJ53 Posted at 2016-1-23 12:16
Yes I think we are all on the same page now.

I hope DJI can come up with something to  ...

My understanding is pushing the power button on the battery resets the day counter.  So at 10 days, that is 3 presses a month.  Personally I would rather them fix the shutting off in mid flight when cold.
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christopherglen Posted at 2016-1-22 22:10
My understanding is pushing the power button on the battery resets the day counter.  So at 10 days ...

I am not so sure about hitting the power button resetting the discharge clock... But they have reduced the problem for cold weather in the last firmware update. Personnelly the problem is not with cold weather, we had the battery drop issue well before the cold weather started this year.

Anyway, let's see what DJI has in store for us and maybe they will provide us with the auto discharge shut off feature

Rich
2016-1-23
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