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Battery Pinout -> Solution for Possible Better Battery Alternative

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Hi all, I have been digging into the battery for the Anafi and wanted to share some of my results. My goal is to build a replacement battery for under $20 that is higher capacity but similar in weight. Also a battery you can hook up to a balance LiPo battery charger such as the B6 charger so you can get increased speed in charging.

First the battery. The Anafi has a 2 cell LiPo rated at 2700mA @ 7.4v. There are several internal circuits within the battery that allow charge from USB, discharge after a period of time, and logic when connected to the drone. These circuits add weight and which can be better suited for a higher capacity battery (if you charge and balance with a 3rd party charger).

Below is the beginning diagram of the connections of the circuity of the Anafi. In an active but unconnected state, the main terminals are active with the left being negative and right being positive. In the center of the battery are 8 additional pins. None have any measurable voltage while in the active & unconnected state (except Cell 1 Voltage). This holds true for when the battery is charging. Cell 1 Voltage is measured to be half of the total voltage of the battery.

On the drone side, all pins and terminals are independent of each other EXCEPT what I call the Drone Detect pin. It matches with the Voltage (Positive) terminal. My belief is when a battery is plugged in the drone, this pin becomes high, and the battery now knows it is connected to the drone.

My next step is to dissemble a battery fully and wire the pins to a logic analyzer to see what signals are being output. Unfortunately, I currently only have one battery and am not ready to dissemble it. My question then is if anyone has a dead, bad, or donate-able battery for me to do the research with? If so please PM me. I will post the results of my finds once I am done.

1514
 

Dronographer

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Thanks for the info, keep us posted and good luck! I have seen "graphene" LiPO HV cells, not sure if they offer more energy density or is merely an advertising gimmick. Would blow your $20 budget but....
 

tuxfool

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Two of those pins will be for the differential data line of USB 2, which I assume is passed through (as opposed to being processed in the battery circuits)
 
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AaronB

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I think you will be hard pressed to get a smaller / lighter battery with the same capacity for $20.
 
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MustangPhil

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Hello,

That’s a nice idea, I’ll post the link about the battery components of the Anafi made by Pablo Sotes.

This French guy (but obviously with Spanish origins), wanted to fly in certain town durings his vacations in Spain with the Anafi. He is a champion in drone races and aerobatics freestyle here in France.

As the Anafi is 320g and the Spanish laws allow to fly in towns even at night and over people if the drone is lower than 250g he decided to exchange the original Anafi batteries with drone racers batteries. The purpose is to have a flyable Anafi under 250g to fly legaly there.

He explains that instead of 25 minutes, he expects 5 to 8 minutes. He describes all internal components of the Anafi battery.
He also says that hopefully, his experiment was supported by friends at Parrot, and he could have some spare batteries to deal with.
He burnt 2 original working batteries before to succeed... he says the internal component sets are very fragile and not intended to be welded or exchanged.

Here is the link (just ask if you need some translations at a certain duration/time) :

 

Dirk_ANAFI

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I know this video.
Obvious is, that there is no way to simulate an original battery without using the original battery PCB.
 

MustangPhil

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Yes, and in the comments of this video, there’s an other guy that seems to be a specialist of one of the Texas Instrument chipset that is embedded in the Anafi Smart Battery PCB. He says that if this component does not detect a +voltage under usual circumstances and at one of its ‘leg’ it will damage the thing.
That leads Pablo Sotes to weld the new battery while the other is still connected to avoid problems (I think I understood that).

I am not a specialist in electronics, but just wanted to warn the original poster of the thread of the risks.
 
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mike_kelly

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Just remember that this is a dangerous project. LiPo cells are in a vacuum because lithium burns when exposed to air. So if you take apart the case and nick one of the cells you can cause a fire or at least a LOT of smoke.

That said I have succesfully, using Pablos work, added a LION that significanly increases capacity and does not weigh any more than the original battery. I actaully think it is more valuable to make a 70g lighter battery to make the Anafi a universally legal 250g drone. I can't fathom why Parrot would not make one as an option.

The battery I used is from Titan and it costs $18. IT was an interesting project but not too practical given the lack of a molded case to protect the exposed circuit and battery during a crash.

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Dronographer

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Waht is the maH rating of the lighter battery and what is the flight time with the leighter airframe/smaller battery rating?
 

AaronB

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That said I have succesfully, using Pablos work, added a LION that significanly increases capacity and does not weigh any more than the original battery.
...
The battery I used is from Titan and it costs $18.

How long was the flight time and how hot did the battery get?
 

tuxfool

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The battery I used is from Titan and it costs $18. IT was an interesting project but not too practical given the lack of a molded case to protect the exposed circuit and battery during a crash.
How much more flight time did you get out of that battery? A basic calculation of 29% extra capacity puts it at ~30 minutes.

Also the lack of a milder case could be rectified by 3d printing some kind of custom enclosure, obviously not as good as moulded plastic but it should prevent issues with exposed electronics.

As a more general point of note, I'm not particularly impressed with prevalence of "smart" batteries in medium-high end drones. There is no reason power management circuits can't be integrated into the main hull, it would make battery packs more cheap.
 
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Kilrah

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There is no reason power management circuits can't be integrated into the main hull, it would make battery packs more cheap.
Sure there is, without built-in circuitry you can't keep precise track of battery level, and that's the main reason. Also you need a more complex charger becasue it has to balance, so you also need a balancing connection...

And from a safety point of view for a consumer product it's much better to have built-in, permanent protection against overcharge/overdischarge, imbalance, overcurrent, short circuits, overtemp etc, then the self-discharge function is good for longevity...
 
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Agustine

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As was posted by a user in the Yuneec forum talking about smart batteries.

"As for “smart” batteries, when they do more than just provide a user an excuse to be lazy or to allow idiots a means to function in an environment requiring intelligence they will serve better purpose. They don’t need to triple or more the cost of a standard battery to accomplish that. The components used to construct a smart battery amount to no more than a few dollars in parts and labor, leaving current pricing without any justification. It puts a lot more money in the manufacturer’s pocket. "
 

RemE

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Sure there is, without built-in circuitry you can't keep precise track of battery level, and that's the main reason. Also you need a more complex charger becasue it has to balance, so you also need a balancing connection...

And from a safety point of view for a consumer product it's much better to have built-in, permanent protection against overcharge/overdischarge, imbalance, overcurrent, short circuits, overtemp etc, then the self-discharge function is good for longevity...
Considering the use by the general public, who don't have the knowledge, tools, and discipline to properly manage and maintain lithium packs, it was probably a good decision to introduce smart packs in the consumer drone space. But it's more annoying and expensive for those of us who are experienced modelers, and we are a minority to these big guys.
 
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NortyNinja

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I myself like many others have briefly looked into this, I have a workshop for repairs to laptops, tablets and general smd electronics, I came by a couple of anafi main boards that were water damaged and repaired them, I still have them of which I think it's about time I played with one and a battery, my initial thought was to look into making it easy to switch the internal batteries in & out of the original battery casing,
My thinking without yet opening a battery was 2nr 18650's 3500mah upto 35amp are 65grams without jacket/case on 84grams with case on. A good make e.g. Eset £17 for 2. At the time I was not looking at reducing weight to account for the 250g limit, but for more fly time and less cost
Now this has been brought up I must go and play.
A couple of photos to show I'm not talking rubbish IMG_0991.JPG IMG_0993.JPG
 
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tuxfool

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Considering the use by the general public, who don't have the knowledge, tools, and discipline to properly manage and maintain lithium packs, it was probably a good decision to introduce smart packs in the consumer drone space. But it's more annoying and expensive for those of us who are experienced modelers, and we are a minority to these big guys.
I wasn't suggesting just plain battery packs, there are plenty of devices that have proprietary battery packs, with management ICs for charging, but not the extensive PCB that is found in the anafi batteries.

But as explained above, the PCB on the anafi only adds a few dollars to the BOM, but it allows them to justify the exorbitant margins they get on battery packs.
 

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