Mini 2 battery disassembly

[mucek]

New owner of Mini 2 ... Plenty of experiences with electronics design of battery management systems and offcourse I needed to open it the second day I got the drone
Electronics is simple, but very well built! the core is BMS/FuelGauge chip (not sure which brand, I did not remove epoxy coating, but it could be Maxim's), charge and discharge enable FETs are AP3N1R8MT (165 A peak, 30 V) and fuse is 30 A. Whole battery is ultrasonic sealed + additional hooks, which was quite a pain in the *** to open ). Nice blue coating is some sort of epoxy, I did not try to remove it to prevent damaging my (only ) battery ... (****, I know I should have bought a fly more pack ...)

Regards,
Gregor

 

[old man mavic]

@mucel while doing what you did make have satisfied your desire to see whats inside the battery case, its not something that should be undertaken, unless you have some knowledge of how to do it safely, i am not sure what it achieved at the end of the day ,this is just my opinion ,sorry in advance if it offends you

 

[mucek]

Hehe, you are completely right! I am way too much down into engineering spheres, so I forget to warn, that this could be dangerous if doing improperly ... And a screwdriver, pushed into charged lipo battery is definitely such scenario!

However, I am quite an expert on batteries and BMS systems, so no problem here Attached my current project from the desk I am working on ... 3S battery managment with accurate fuel gauge, programmable BMS with secondary protection, USB PD buck-boost quickcharger (6 A).

Regards,
G

 

[Kilrah]

i am not sure what it achieved at the end of the day

Just wanting to know how it's done?

(not sure which brand, I did not remove epoxy coating, but it could be Maxim's)

Probably TI since that's what they use on their other aircraft.

 

[mmdrevo]

looks interesting.

 

[mucek]

Probably TI since that's what they use on their other aircraft.

Now I'm getting worried!

TI is high on my hatelist ... Had an unpleasant experience with quite some of their chips, although I must admit, they are among the cheapest ...

Worst experience was 1S LiIon charger, which charged batteries up to 4,5 V due to missing capacitor in their datasheet ... After several lost hours (and batteries) and being in contact with their team we found the difference (one 1 uF capacitor!) in their documentation and their working devboard ... After adding this, charger worked fine. (and they made new revision of the datasheet within a week! )

 

[Piranha]

Great post, thanks for the info,Man

 

[Skybuyer]

You're a better man than I, Gunga Din.

 

[Sanch7a]

Nuevo propietario de Mini 2 ... Muchas experiencias con el diseño electrónico de sistemas de gestión de baterías y, por supuesto, necesitaba abrirlo el segundo día que compré el dron.
¡La electrónica es simple, pero muy bien construida! el núcleo es el chip BMS / FuelGauge (no estoy seguro de qué marca, no quité el recubrimiento epóxico, pero podría ser Maxim), los FET habilitados para carga y descarga son AP3N1R8MT (165 A pico, 30 V) y el fusible es 30 A. Batería completa es sellado ultrasónico + ganchos adicionales, que fue bastante doloroso para abrir ). El bonito revestimiento azul es una especie de epoxi, no intenté quitarlo para evitar dañar mi (única ) batería ... (****, sé que debería haber comprado un paquete de mosca más ...)

Saludos,
Gregor

¡Hola! viendo como está por dentro, ¿habría posibilidad de quitar la carcasa de la batería del mavic 2 y poder meterla en el mavic 1? Sería interesante tener esos V extra, los conectores son los mismos.

 

[mucek]

Hi, please write in English - or at least paste from google translate!

No, it wouldn't be possible, I guess that battery is too big (mechanically) as it is square-shaped (mini 1 has 2 round 18650 cells).

 

[cstout]

I’m actually really surprised by this. I thought the mini two batteries were still 18650’s!

 

[André Di Urechia]

New owner of Mini 2 ... Plenty of experiences with electronics design of battery management systems and offcourse I needed to open it the second day I got the drone
Electronics is simple, but very well built! the core is BMS/FuelGauge chip (not sure which brand, I did not remove epoxy coating, but it could be Maxim's), charge and discharge enable FETs are AP3N1R8MT (165 A peak, 30 V) and fuse is 30 A. Whole battery is ultrasonic sealed + additional hooks, which was quite a pain in the *** to open ). Nice blue coating is some sort of epoxy, I did not try to remove it to prevent damaging my (only ) battery ... (****, I know I should have bought a fly more pack ...)

Regards,
Gregor

Hello Gregor, do you have a photo where the connection from the cell terminals to the PCB can be seen? Thanks in advance.

 

[DanMan32]

I’m actually really surprised by this. I thought the mini two batteries were still 18650’s!

Nope, LiPo. Voltage is even different, comparable to the other Mavics.

 

[izometric]

Do you have any idea if there is (or could be) any electric heater (nikel foil) on that battery?

It would be interesting to learn how the battery reaches so fast 25C in freezing temperatures.

 

[mucek]

No need Internal battery resistance does the job well enough, when flying. Currents are quite strong and cool battery has a much higher internal resistance, which is the reason for initial heating.

 

[izometric]

What is the internal battery resistance?

How much current would you need to draw from the battery so that internal resistance generates enough heat to raise the temperature from 10C to 25C? I mean on the ground when the temperature raises abruptly as soon as you power the drone.

What is going to draw that much current? The camera? The processor? Doing what computations?

 

[mucek]

Aaah, this is probably another issue: it is heating from the drone's CPU unit, which gets pretty hot and probably heats the battery casing. I guess at least!

Will check this on mine, seems interesting question, especially because temperature sensor inside the battery should be on BMS PCB, which faces drone's back and therefore shouldn't be affected by the drone's CPU internal heating too much.

Regards,
Gregor

 

[Skynet5]

Top work man. Love this stuff and was thinking of doing it myself. Now I don't need to.

 

[Deleted member 103366]

@mucek
Just as a matter of interest do you have the equipment and software to switch whatever it is on the control board (gas gauge?) that switches something ( the FETs? ) to open circuit when the voltage gets too low and 'permanently' disconnects the output terminals from the cells.
I have just lost a Phantom battery to this, my fault, and no I am not considering trying to revive it, the cell voltage was way too low for that to be safe, I check the cell pack with a voltmeter.
Also does this 'whatever' need to have the batteries attached to the control board when this thing is reset?
I envisage a time when complete batteries for the Phantom 3 are not available and cells will have to be replaced, I am wondering if this thing will trip if the old cells are connected BEFORE the new cells are connected or jumpered to the control board.

 

[d0ugparker]

Can you give an accurate pinout? Which of the six connections is its ground?

Thanks