About reviving a Mavic Pro battery

[cachi1915]

I’ve searched and I haven’t found anything so I suppose there’s not topic talking about this, but I suppose that this is something common, so I need to try it.

I’ve a Mavic Pro with two batteries, I use to take a lot of care of all my equipment, but I didn’t follow everyone recommendations and I didn’t identified the batteries. Due that I didn’t noticed that I wasn’t charging one of them for a long time and now is not possible to charge it.

I have searched the web and I’ve already tried all standard recommendations, so I’ve started my project.

I need to say that I’m doing this for learning, probably I won’t use this battery for flying if I get it recovered. I will use it for testing for firmware updates, and any other landed operations.

First of all I’ve disassembled the battery.

Using a voltmeter I’ve identified the cell that is below the minimum voltage.

Now I need recommendations about how to charge it and what charger, time and voltage do you recommend me.

Thanks! Regards!

 

[Deleted member 103366]

If the method of operation of the controller board is the same as with Phantom 3's there is a chip that controls the connection to the main current terminals, if the battery's voltage gets too low the chip goes open circuit and you need specialised equipment to reset it. This prevents charging and discharging, I am not sure if it is possible to by pass it. If I can find the relevant page I will post the link. Mean time you could try googles for resetting phantom 3 battery.
I think it was on github and I did find this.

Battery firmware · Issue #17 · o-gs/dji-firmware-tools

i notice the battery firmware is not encrypted. i wonder what could be done to the battery controller so aftermarket batteries could be connected

github.com

which seems in the same vein, I also saw a couple of dismantled mavic batteries in amongst the images stemming from a google for reset phantom 3 battery

 

[cachi1915]

I’ve found this post https://www.electricrcaircraftguy.com/2014/10/restoring-over-discharged-LiPos.html

This guys seems to have a lot of info about the procedure for LiPo reviving, I’m trying to find a nice charger.

I’ll keep the thread updated

Thanks!! Regards

 

[DanMan32]

If the chip hasn't disabled itself, then you only need to get the weak cell kickstarted. I'd say 3.2v would be a good place to start. You'll want to limit the current.

 

[cachi1915]

I've openned this thread in the Mavic Pro Discussion forum. It should be moved to the Mavic Hardware Mods? Where are supposed to be placed this type of topics?

 

[cachi1915]

Seems that DJI use to glue the connector so I’ve broke it while disassembly the connections.

As far as I’ve read cables are one for each cell and tone last one for the negative.

I found two similars connectors in an old laptop, one Pentium III.

One is too small, it won’t never work.

The other one has the right size, but not the correct shape

The next step is to adapt this second connector to the correct shape.

 

[cachi1915]

I've managed to start charging the cells very slowly and it seems it's working. I'm describing the process in the Mavic Hardware Mods forum

 

[cachi1915]

Just tested the battery cells few minutes ago. Now all cells are 2,0v or above and the complete battery is near 3,0v. You can see it here: https://youtube.com/shorts/QBI4lnjcAqw

I’m waiting for a better charger to increase the voltage to try to increase the charge to 3v

 

[quaddamage]

Have you seem the video with needles?:

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[quaddamage]

And here you can find something about free software with GUI:

Mavic 2 Pro-Zoom Battery · Issue #196 · o-gs/dji-firmware-tools

I have a Mavic 2 Battery that was in storage too long and a cell went under voltage too far and the BMS Chip locked it out. Opened it up hoping to use the tools to open and clear the PF flag but th...

github.com

Note: I didn't tried that myself, you may want to be careful with executing programs from unknown source.

 

[PyroSk]

This is probably an old thread, but I recently had a Mavic pro battery that had been unused for a long time and the cells went below the threshold of the battery management chip to throw a permanent pf flag to disable the output or charging of the battery even once opened and cells manually charged to a good 3.2 volts.

I know about connecting to the chip via IC2 with an USB to IC2 bridge adaptor and using python to remove the flags, but with all my computer gear in storage I was able to do it another way without programming only using DJI assistant and refreshing or upgrading the firmware by jump stating it connected to the drone.


Is this still relevant? I think the same technique could be used with all DJI battery controller.

Is anyone interested? And I'll keep explaining how too.

 

[quintesse]

Is anyone interested? And I'll keep explaining how too.

I'm indeed interested. I've got 3 batteries that have been in long storage (after moving house) and they're all completely dead. So far nothing I read that could fix this (without opening them) has worked.

 

[Helo Nugget]

This is probably an old thread, but I recently had a Mavic pro battery that had been unused for a long time and the cells went below the threshold of the battery management chip to throw a permanent pf flag to disable the output or charging of the battery even once opened and cells manually charged to a good 3.2 volts.

I know about connecting to the chip via IC2 with an USB to IC2 bridge adaptor and using python to remove the flags, but with all my computer gear in storage I was able to do it another way without programming only using DJI assistant and refreshing or upgrading the firmware by jump stating it connected to the drone.


Is this still relevant? I think the same technique could be used with all DJI battery controller.

Is anyone interested? And I'll keep explaining how too.

I'm absolutely interested!

 

[Glennyboy]

This is probably an old thread, but I recently had a Mavic pro battery that had been unused for a long time and the cells went below the threshold of the battery management chip to throw a permanent pf flag to disable the output or charging of the battery even once opened and cells manually charged to a good 3.2 volts.

I know about connecting to the chip via IC2 with an USB to IC2 bridge adaptor and using python to remove the flags, but with all my computer gear in storage I was able to do it another way without programming only using DJI assistant and refreshing or upgrading the firmware by jump stating it connected to the drone.


Is this still relevant? I think the same technique could be used with all DJI battery controller.

Is anyone interested? And I'll keep explaining how too.

Yes very interested as I have 2 batteries that have died and won’t take any charge.

 

[davo1]

Yes, please I'm also interested in this.

 

[caryflyboy]

That would be interesting

 

[mobilehomer]

You guys should try contacting DJI directly. You migh be pleasantly surprised.

 

[caryflyboy]

I only have one that won’t charge, the one that came with it when I bought it from the church rummage sale, got 2 new ones from flea bay, but would be nice to have that one charge enough to use for compass calibrations unless it would charge completely and be ok. Then would have 3 batteries for it.

 

[arw]

Have you seem the video with needles?:

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Awesome, that did the trick. Brought my 3 batteries back to life. What I did (charge + unlock):

- Opened the battery up
- Disconnected balancer plug and V+
- jump-started the battery with a PSU by slowly increasing voltage to 7,7 V until current flow stopped
- Then my balanced LiPo charger could take over (custom balance plug)
- Re-connected everything
- Now the battery was full (all 4 LEDs solid) but still useless ("DJI lock")

- Followed the steps in the video above:
- As I already had the batteries open, I permanently soldered a cable to SDA and SCL
- I used my Raspberry to remove the permanent failure flag
Additional info:
- The battery has to be powered on to be detected
- I had to install smbus2 and needed to add "--bus smbus:1" to the commands
- This is the repo
dji-firmware-tools.git