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Battery Mod Info

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Actually the smart board (or BMS as they are referred to) is a VERY complex and complete piece of engineering that has the ability to calibrate for battery characteristics and for the ability to determine, based on programmed parameters, when and if a cell will fail, BEFORE it fails. It tracks dozens of parameters, knows the offsets between batteries for balancing, knows tons of stuff about how the cells react and even trends tha data over the lifecycle of the pack to keep it useable long after most packs would be considered "damaged". Ie, the DJI packs "age" very well.

There is a lot of stuff that happens during manufacturing and there is some stuff you can do "after the fact", but one does not equal the other in regards to being able to "repurpose" packs (ie, load new cells in an already existing pack). On assembly they tell the pack to self-calibrate for the cells installed. That way it knows what is installed and can know exactly how they need to operate based upon formulation.

I am still working with a number of smart boards and getting a handle on the technical side of things (I have all the specs for all the chips used, their protocols and I am mapping out the I2C protocol as well as the chip-level configurations and capabilities), so it may be anywhere between a week or a month before I am able to get to a point where I can say EXACTLY what can be repurposed and what cannot.

But, if anyone thinks it is just a battery meter and balance system that keeps the voltages the same, they are way off... It is a very complex system that affords for variances within cells as well as tracking discharge and charge characteristics to keep everything in "balance". Quite frankly, almost all of the DJI drone battery systems use just as a complex system. Most other higher-end drones do as well. Then you have failures, like Parrot Anafi that won't show the voltages of their batteries and constantly run them into the "damage zone" on the low end. They "fixed" it in their USA offerings by increasing the size of the cell packs and changing the parameters, but they did not backward engineer it into their previous offerings thus if you aren't aware you are killing your batteries by not bringing the drone back before voltages get too low. This is all well documented and known on the other forums.

So, to sum up, if you just put a new set of cells into an existing DJI battery, it is not calibrated for those cells. It could be WAY OFF, and you won't know until you get a power fail out of the blue. Also if the proper formulation is not configured on the smart board it will not be monitoring the configured cells properly. If it is a DJI pack to DJI pack transplant it is pretty safe to say they are the same, but ALL of the alternative cell transplants are running a risk without knowing EXACTLY the characteristics of the cells being used (which is why you have to go to the manufacturer of the cells like I did to get all of that information to program the system appropriately).

Also, for those that are still looking at the addition of extra external packs, the issue there is you change the entire characteristics of how the smart board monitors power usage and end up messing with its ability to allow the pack to provide proper voltage and current. Unless certain electrical things are taken care of (that require changes to the TB47/TB48 packs themselves) you will always run the risk of tripping the charge mode and having the aircraft fall from the sky.
As far as the recalibrate with new cells, is it true that if you run the newly re-celled batt down to 3% you can induce a new recalibration? (both tb48 and tb47)
 
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As far as the recalibrate with new cells, is it true that if you run the newly re-celled batt down to 3% you can induce a new recalibration? (both tb48 and tb47)
That's to be investigated, but a good friend of mine swear that it works. He did that by very slow discharge and balancing first, bypassing the "smart" board and using high quality charger/discharger with custom balancing harness. I have this harness and I'm about to perform calibration ASAP. Stay tuned ...
 
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That's to be investigated, but a good friend of mine swear that it works. He did that by very slow discharge and balancing first, bypassing the "smart" board and using high quality charger/discharger with custom balancing harness. I have this harness and I'm about to perform calibration ASAP. Stay tuned ...
Please do update. I have been exploring the idea of a making for myself an easily swapped battery pack with the brainboard installed on the craft. My thought is to mount one original/OEM TB48 or 47 brain on the craft and then swap after market/diy packs (with properly configured cells and sensors). It would involve using a 3d printed mount/mechanism to hold the swappable OEM board in place for flight on the craft and an easily bridged connection/connectors for power and data from the battery pack(s). I don't know enough about the board's rubric/design to take this beyond just the idea phase, I do know that on other DJI batteries of the Inspire era, it is possible to short a few of the board terminals to reset.

Also, terribly interested in your mentioned harness. If you have any specs/diagrams, it would make my day. Cheers.
 
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Please do update. I have been exploring the idea of a making for myself an easily swapped battery pack with the brainboard installed on the craft. My thought is to mount one original/OEM TB48 or 47 brain on the craft and then swap after market/diy packs (with properly configured cells and sensors). It would involve using a 3d printed mount/mechanism to hold the swappable OEM board in place for flight on the craft and an easily bridged connection/connectors for power and data from the battery pack(s). I don't know enough about the board's rubric/design to take this beyond just the idea phase, I do know that on other DJI batteries of the Inspire era, it is possible to short a few of the board terminals to reset.

Also, terribly interested in your mentioned harness. If you have any specs/diagrams, it would make my day. Cheers.
The harness is actually a standard 6S balancing cable with one end modified for proprietary DJI multi-pin plug, that's all. It allows to perform a detailed maintenance of DJI TB battery pack, assuming availability of adequately sophisticated charger (i.e. iCharger NZ - Shipping Worlwide!https://www.icharger.co.nz. ). Here's a video DJI Inspire 1 TB 47 battery repair broken cell . Richard Josephson ([email protected]) may be able to make this harness for you.

As for your project ... Yes, that's basically the idea we're all after at this moment ... The TB 47/48 board's sophistication and raw LiPo cells sourcing seems to be the obstacles no one was able to overcome by far. Sooner or later somebody smart enough will dissect this board and find the way to program it for a given battery pack, I hope ...
 
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The harness is actually a standard 6S balancing cable with one end modified for proprietary DJI multi-pin plug, that's all. It allows to perform a detailed maintenance of DJI TB battery pack, assuming availability of adequately sophisticated charger (i.e. iCharger NZ - Shipping Worlwide!https://www.icharger.co.nz. ). Here's a video DJI Inspire 1 TB 47 battery repair broken cell . Richard Josephson ([email protected]) may be able to make this harness for you.

As for your project ... Yes, that's basically the idea we're all after at this moment ... The TB 47/48 board's sophistication and raw LiPo cells sourcing seems to be the obstacles no one was able to overcome by far. Sooner or later somebody smart enough will dissect this board and find the way to program it for a given battery pack, I hope ...
I'll follow up on those leads, thanks. The cells seem to be a problem due to size BUT any cell that can supply the same power specs (or better) should be workable, but the flight/batt cage may need to be modded. Is all that would be needed is a reset/reflash of the board I believe or a way to trick it to lose count of cycles etc
 

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