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Mavic Mini BatMan

aeropic

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Joined
Dec 10, 2019
Messages
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Age
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Location
France
Hello,
I designed this little gadget in order to manage the batteries without the need to place them inside the MM body.
BatMan is a simple way to manage the state of charge and different parameters of your DJI Mavic Mini Intelligent Battery.
In a future version, I may add the capability to discharge the batt for hibernation down to 60% of charge.
The battery Manager displays the following parameters:

  • Full charge capacity
  • actual capacity
  • percentage of charge
  • total voltage
  • each cell voltage
  • number of cycles (charge/discharge)
  • charge/discharge current
  • date of manufacturing
  • name of the battery
everything you need to build one : Mavic Mini BatMan by aeropic
see it in action here :
 
Hello,
I designed this little gadget in order to manage the batteries without the need to place them inside the MM body.
BatMan is a simple way to manage the state of charge and different parameters of your DJI Mavic Mini Intelligent Battery.
In a future version, I may add the capability to discharge the batt for hibernation down to 60% of charge.
The battery Manager displays the following parameters:

  • Full charge capacity
  • actual capacity
  • percentage of charge
  • total voltage
  • each cell voltage
  • number of cycles (charge/discharge)
  • charge/discharge current
  • date of manufacturing
  • name of the battery
everything you need to build one : Mavic Mini BatMan by aeropic
see it in action here :
Very very impressive. ?
 
Very very impressive. ?
Thanks, but not that complex, everything is ready to read from the BMS... The only complex part was to reverse engineer the I2C protocol and understand how the BMS chip is working !
 
The only complex part was to reverse engineer the I2C protocol

Still not clear what to reverse-engineer in the provided list of parameters ?
  • Full charge capacity
  • actual capacity
  • percentage of charge
  • total voltage
  • each cell voltage
  • number of cycles (charge/discharge)
  • charge/discharge current
  • date of manufacturing
  • name of the battery

They are standard SBS v1.01 compatible, well documented and ready-to-read over battery SMBUS port.

What is really "sweet" and most interesting things for reversing in that battery these are the firmware and proprietary DJI-specific smbus registers.
 
Still not clear what to reverse-engineer in the provided list of parameters ?


They are standard SBS v1.01 compatible, well documented and ready-to-read over battery SMBUS port.

What is really "sweet" and most interesting things for reversing in that battery these are the firmware and proprietary DJI-specific smbus registers.
Well, I did not know this SBS 1.01 protocol and I started by a spy on the I2C bus, trying to find first the slave address and trying to de commutate the logs. Then somebody put me on track with the name of a nearly compatible BMS chip (BQ30z554) which was very helpful to understand the protocol...
This is what I call reverse engineering. This being said, I'm ready to learn, any new information would be appreciated ;-)

EDIT: thanks I found a SBS spec here : http://sbs-forum.org/specs/sbdat110.pdf
 
Incredible !

An amazing gadget, but it would be wonderful if you can add the ability to put the batteries in storage mode.

R.
Thanks, adding the controlled discharge is really easy and is in my to do list! Stay tuned it will come ;-)
 
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Reactions: Capt KO
Thanks, adding the controlled discharge is really easy and is in my to do list! Stay tuned it will come ;-)
The discharge part could easily be done with a USB battery pack. The same one used for charging. Now you just need to make it smart enough to stop at approximately 50%.
Great idea, keep it up.
 
The discharge part could easily be done with a USB battery pack. The same one used for charging. Now you just need to make it smart enough to stop at approximately 50%.
Great idea, keep it up.
good idea, that would even save some energy ;-)
 
The discharge part could easily be done with a USB battery pack. The same one used for charging. Now you just need to make it smart enough to stop at approximately 50%.
Great idea, keep it up.
Thanks for this idea, it is implemented in the V2 device. It drains around 370mA at 8v to push 500mA at 5V into the smartphone.
 
This is really cool. Nice job. It would be even better if it would charge to 60%. I know that would involve more circuitry but think it would be better long term for the battery.
 
This is really cool. Nice job. It would be even better if it would charge to 60%. I know that would involve more circuitry but think it would be better long term for the battery.
Have you seen I made a V2 able to discharge the batt to a programmed value (80% or 60% if you wish) ?
 
Have you seen I made a V2 able to discharge the batt to a programmed value (80% or 60% if you wish) ?
Yes I saw that, but was thinking that charging to 60% would be better then charging to full then draining to 60%. The charge, discharge then recharge when need, would count as an extra cycle count on the battery. Where as a straight charge to 60% then full charge when need would not.

This is just a theory as I do not know what the battery uses to determine charge cycles, maybe it wouldn't make a difference. On this note, do we know if the mavic mini will still allow you to use a battery with more then 200 cycles?

Thanks for all the work you have put into this.

Ryan
 
Aeropic,
Fabulous device. Very helpful for maintaining and storing MM batteries to get optimal use from them. Once you have all the features you want to include in the BatManV2, is there a chance you'll be offering it for sale.
Sharing the list of materials and instructions on how to make it is admirable but for those of us without access to a 3-d printer and without electronic and technical skills, it doesn't help us, so could you please consider making and selling the BatManV2 to people like myself? It would be very helpful and greatly appreciated. Thanks.
 
Aeropic,
Fabulous device. Very helpful for maintaining and storing MM batteries to get optimal use from them. Once you have all the features you want to include in the BatManV2, is there a chance you'll be offering it for sale.
Sharing the list of materials and instructions on how to make it is admirable but for those of us without access to a 3-d printer and without electronic and technical skills, it doesn't help us, so could you please consider making and selling the BatManV2 to people like myself? It would be very helpful and greatly appreciated. Thanks.
thanks!
Sorry, it is not in my plans to sell them. I don't even know how much it would cost...
 

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