Battery mod thread

[Justinswidebody]

Some people reported they did it successfully after battery firmware being updated, there is even video on youtube where Mavic Mini user replaced stock cells with Sony 3000mAh ones and did then hover testing.
In comments he confirmed Drone and battery both were updated just upon unboxing (otherwise it was not possible to take-off).

It is not possible to take off without the mini being updated this is true.

I'm just telling you my experience. I sacrificed 6 batteries. I tried live swaps and everything without success. Just be warned before you try. Maybe when doing the live swap all batteries need to be the same volt. I don't know.

 

[mavicn00b]

Only if you never did the initial battery update from the initial launched mavic mini.

How does it know the cells have been replaced?

 

[Justinswidebody]

Only thing I can think of to make the live swap definitely work would be to have almost identical voltage, and to also splice into the balance wire. This way there is no way for the bms to know anything is happening.

When I tried a hot swap, I tried by keeping just the positive and negative hooked up with another battery pack.

Best way to tap into the balance lead would be to use a wire tap connector. Therefore you can easily remove it after the swap has happened.

 

[Marcuchinonis]

Only thing I can think of to make the live swap definitely work would be to have almost identical voltage, and to also splice into the balance wire. This way there is no way for the bms to know anything is happening.

When I tried a hot swap, I tried by keeping just the positive and negative hooked up with another battery pack.

Best way to tap into the balance lead would be to use a wire tap connector. Therefore you can easily remove it after the swap has happened.

Today, I own two new batterys. The first I've checked says "battery firmware update avalaible" on Dji fly. Like you know, to check that you have to switch on the drone with battery inside, and to do this, you have to activate the battery with charger or drone itself with the mini-usb cable before. I asume the second battery is the same like the one I've checked yet. The question is what should you do? Take apart the first or the second one? The first sows ""battery firmware update avalaible", but is activated. The second also has the "battery firmware update avalaible", but is not activated yet. The battery, just activated, shows 3,51V. I think is a good idea to make a hot swap with a valance connector and another 3,51V battery. How should you do to sold on balance borne?

 

[everBit]

When I tried a hot swap, I tried by keeping just the positive and negative hooked up with another battery pack.

Now it's clear why all your 6 attempts were failed. You violated the main rule while working with smart flash-based batteries to "NEVER DISCONNECT SENSING/BALANCING WIRES FIRST".
It does not matter it's cold or hot-swap in that case. Leaving activated uC without measuring cells voltages in multi-sequential configuration (i.e. 2S, 3S etc) even for short period will cause error flag (voltage imbalance) being set in uC integrated EEPROM.

Correct way for Cold-Swap:
1. Disconnect 2S (7.4V) wire first.
2. Disconnect 1S (3.7V) wire second.
3. Disconnect Ground wires at last.
4. Prepare new cells (cells voltages to be equalized)
5. Connect Ground wires first.
6. Connect 1S (3.7V) wire second.
7. Connect 2S (7.4V) wire at last.
8. Activate battery bms in the charger.

For hot-swap as you mentioned you should equalize new cells voltages and never disconnect middle wire.

 

[everBit]

Me strongly beleive all bms remains "magic" untill activated in the charger.
While it sleeps you could do with it what you want.

 

[Marcuchinonis]

I strongly beleive all bms remains "magic" until activated in the charger.
Until it sleeps you could do with it what you want.

I think so too. But when activated with a new cells, what can I do? Could we swap cells again like if was "magic"?

 

[Justinswidebody]

Today, I own two new batterys. The first I've checked says "battery firmware update avalaible" on Dji fly. Like you know, to check that you have to switch on the drone with battery inside, and to do this, you have to activate the battery with charger or drone itself with the mini-usb cable before. I asume the second battery is the same like the one I've checked yet. The question is what should you do? Take apart the first or the second one? The first sows ""battery firmware update avalaible", but is activated. The second also has the "battery firmware update avalaible", but is not activated yet. The battery, just activated, shows 3,51V. I think is a good idea to make a hot swap with a valance connector and another 3,51V battery. How should you do to sold on balance borne?

You are good to do whatever you want with any of the batteries. Can I ask why you only want to swap the cells? I'm assuming you don't want batteries on top of the mini? In my opinion it's best to make it where you can swap batteries at all times like I have done.

 

[Marcuchinonis]

You are good to do whatever you want with any of the batteries. Can I ask why you only want to swap the cells? I'm assuming you don't want batteries on top of the mini? In my opinion it's best to make it where you can swap batteries at all times like I have done.

I want to do like you. I'd like to make a "magic board" to try several batterys (lipo, Lihv, Lion, etc..) on top, sides, etc...
What sould you take apart? The activated or unactivated one? Two are un-updated.

 

[everBit]

But when activated with a new cells, what can I do?

One should deactivate bms first.
Exact procedure usually differs across type of embedded uC used.

 

[Justinswidebody]

I want to do like you. I'd like to make a "magic board" to try several batterys (lipo, Lihv, Lion, etc..) on top, sides, etc...
What sould you take apart? The activated or unactivated one? Two are un-updated.

I think both are fine to do whatever you want with. There are a few YouTube videos on how to take apart, but if you don't plan on reusing the plastic sleeve then it's a little easier.

 

[Justinswidebody]

Now it's clear why all your 6 attempts were failed. You violated the main rule while working with smart flash-based batteries to "NEVER DISCONNECT SENSING/BALANCING WIRES FIRST".
It does not matter it's cold or hot-swap in that case. Leaving activated uC without measuring cells voltages in multi-sequential configuration (i.e. 2S, 3S etc) even for short period will cause error flag (voltage imbalance) being set in uC integrated EEPROM.

Correct way for Cold-Swap:
1. Disconnect 2S (7.4V) wire first.
2. Disconnect 1S (3.7V) wire second.
3. Disconnect Ground wires at last.
4. Prepare new cells (cells voltages to be equalized)
5. Connect Ground wires first.
6. Connect 1S (3.7V) wire second.
7. Connect 2S (7.4V) wire at last.
8. Activate battery bms in the charger.

For hot-swap as you mentioned you should equalize new cells voltages and never disconnect middle wire.

Thanks for the guide. Are you positive this works with updated battery?

It doesn't matter how you do it with a battery that hasn't been updated which is strange.

 

[everBit]

Not have enough statistic for Correct Cold-Swapping on Updated Batteries.
Successfull recelling (on youtube) was done by Correct Hot-Swap method.
Still not have these new generation batteries for experiments to check the methods which many times confirmed on the older generation DJI Mavic Pro, Phantom's and Inspire's ones.

 

[Justinswidebody]

Not have enough statistic for Correct Cold-Swapping on Updated Batteries.
Successfull recelling (on youtube) was done by Correct Hot-Swap method.
Still not have these new generation batteries for experiments to check the methods which many times confirmed on the older generation DJI Mavic Pro, Phantom's and Inspire's ones.

Do you have a link to the video?

 

[everBit]

it's here (sorry in Russian). There is no focus on the swapping method but in comments author confirmed it was done by duplicating the power of both cells.

 

[Liamjason123]

This wod be worth a pretty penny if you could produce this to sell

You are good to do whatever you want with any of the batteries. Can I ask why you only want to swap the cells? I'm assuming you don't want batteries on top of the mini? In my opinion it's best to make it where you can swap batteries at all times like I have done.

 

[Justinswidebody]

This wod be worth a pretty penny if you could produce this to sell

I agree, I wish I could. But it would cost the price of a dji battery and then labor and shipping.... And that's if non updated dji batteries are able to find.

 

[exceptional]

IC marked as BQ9003. You can try to read eeprom contents with several apps as UBRT, BE2Works etc.

 

[Marcuchinonis]

Good news
Finally, I own a magic board. I’ve done a cold swap on a un-updated and activated battery. For swap, I’ve followed the instructions by Everbit and Justinwidebody. Thanks a lot

 

[Justinswidebody]

Good news
Finally, I own a magic board. I’ve done a cold swap on a un-updated and activated battery. For swap, I’ve followed the instructions by Everbit and Justinwidebody. Thanks a lot View attachment 89123

Congrats!!! How do you plan on incorporating it into the mini?