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Closer Look at the DJI Charge Hub & Mods

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A closer look at the DJI Inspire 2 Charge Hub.


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I decided I wanted to make some ‘improvements’ to the stock DJI “Coke” can hub and thought I would share some info on it as while this may seem a very standard part of the Inspire 2 package there is a lot of interesting engineering going on here.


To get starting you need to remove the top of the hub, this is held on with 4 clips, a good hard pull will release it


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Once removed you can see the light guide and clips for the plate, looking inside the hun its self removing the lid reveals some of its secrets


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You can see a metal ring that surrounds a PCB than does down the middle with the power connector attached, surrounding this you can see some more boards on each side, next you need to lift out the four release buttons, note these have a small spring attached


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Next you need to do the same with the bottom plate, this is also held with clips and some persuasion will release this the same way as the top


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Once removed it exposes the bottom, just like the top you have another metal ring attached to the PCB, it also now becomes clear that the hub consists of 4 quarters that lock to gather and are held in place by there top and bottom via 4 tubes.


Here you can also see the buzzer, USB port and switch



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Next you need to remove one of the four quarters that hold it together, where they meet there is a strip with the light guide attached, you will need to remove two of these, they are held on with a clip top and bottom and some adhesive along its length, warm this with a hair drier will help remove it with out damage, gently prise out from the top and pull out to remove


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Once removed you can now lift off one of the 4 segments to reveal the battery power connect that is mounted on a PCB attached to the ring at the top and bottom


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Looking at this closely its an interesting setup with the PCB being soldered either side to the ring with a screw in place to told it secure


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Now the one side is off you can simply spread the housing open and remove the whole centre charing module


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Looking at it a lot more closely you can now see how its setup, there is a centre PCB that runs the full length with a metal ring either side, then there are four identical boards that mount to that ring and are soldered top and bottom, behind each board there is a ribbon cable that goes from each to the main PCB.


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To remove of of the outer PCB’s you need to remove the solder and screw, this revels the internal ribbon cables that go between each one


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Removing the other boards shows the other parts of the internal PCB


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End of Pt 1
 
Pt 2

Looking at the battery connector board its self on the back there is the ribbon input and a number of control FET’s


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After investing how the hub works its very similar in design to the smart battery its self, Voltage enters via the main connector and is sent directly eo each battery board via the top and bottom ring, top being positive and bottom being negative, its then routed to the 2 FET’s on the back of each board that control supply to the pack its self, these are controlled by the main PCB via the ribbon cable, there is no direct cell balancing in this hub its purely got the Voltage and data pins.



Looking closely at the board the pin out is as follows


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Green = RX and TX

Purple = BAT 0 AND BAT 0 IN

Blue = Negetive (Note its 2 pins one one side and just the single on the other)

Red = Positive (4 Centre Pins)


Now I was at this point I wanted to take a input to be able to supply battery voltage directly to each pack, to do this I have soldered a wire to the 4 centre pins the battery side of the FET’s


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This was done to each board, it also meant removing some aplastic and putting some holes in the centre structure to get cables to the top


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Once complete the unit is re assembled, I now have four wires coming out the top of the centre module each attached to the battery terminals directly, for the negative I soldered a single wire to the bottom ring that joins to each board


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Once reassembled I attached four XT60 to test it was all working correctly



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While not pretty it worked as intended, the Hub still worked as it should via the DJI input but I now also have a direct battery input via XT 60 to allow me to use it with my custom Inspire 1 charger I built.


Final Job after testing was to tidy up and 3d print a ring for the top to hold the XT60 connector and make it look more like what it should be





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Next job is to work out how the battery control is done and how to turn on the packs.
 
Finally got around to modifying my home built Inspire 1 Charger to be used with the hub.

All working as expected, man glad I’m able to charge back to storage level again and more than one pair at once.

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On reflection a single multi Pin plug would be nice and much cleaner but in reality this gives much more options.
 
How did you get the batteries to turn on and accept incoming power? Also can you charge all 4 simultaneous or does the board still limit that?

Thanks, and great work
Jason
 
The batteries will begin to charge when voltage is applied by them selves.

I can charge all packs simultaneously via the XT60 to each or just like before via the power connector.

So to charge each pack at the same time I just have to supply each XT60.

Also a small note is each XT60 points at the port it’s supplying.
 
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Do I understand that the stock charger does NOT balance the batteries? That would not surprise me. Does your mod add that feature?
 
Correct cell balancing is handled in the battery it’s self, there is no external access to individual cell taps so no charger can balance with out massive modification to the battery it’s self.
 
Correct cell balancing is handled in the battery it’s self, there is no external access to individual cell taps so no charger can balance with out massive modification to the battery it’s self.
Hmm. It must do a pretty poor job of doing so then. I've had two batteries with "Broken Cell" errors, which means a cell deviation of 0.1 or greater, much like the photo above. I've been looking for a 3rd party charger that will actually maintain the batteries better than the Hub charger sees to do. You know, like getting them on a safe storage charge and the like. Thanks for the feedback.
 
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Hmm. It must do a pretty poor job of doing so then. I've had two batteries with "Broken Cell" errors, which means a cell deviation of 0.1 or greater, much like the photo above. I've been looking for a 3rd party charger that will actually maintain the batteries better than the Hub charger sees to do. You know, like getting them on a safe storage charge and the like. Thanks for the feedback.

The cell balancing is a tricky one as tbh it’s not common and the DJI battery setup for the Inspire was 2P6S so one cell being out is actually a pair, DJI have gone for the safer approach and lock the pack down if they deviate over a certain level, in the passed while some have been able to recover packs with large imbalance more often than not it’s a true sign of something being bad tbh.

We assume the TB50 is of the same setup but it’s not confirmed.
 
Perhaps. I've never had a battery die an early death in normal use, and now have two of these go bad in less than 15 cycles. I feel I have to question their process.
 
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