A video worth a ton of text !
See the device running here:
What is inside ?
Well almost nothing excepted an ESP32 MCU.
No modification is done on DJI's side. The battery and the charger are totally unchanged and unopened.
How to hide the electronics ?
Simply with a 3D printer. You can get the parts here
The yellow connectors are XT30 (male and female). Solder them with as short wires as possible. The black tabs should prevent the connectors to slide.
The smallest ones are dupont pins (male and female). All this is epoxy glued into the 3D printed case.
It snaps into the charger and connects with the battery nicely.
The ESP32 lolin Lite board is hidden into the top box. The lid slides and snaps, so that no screws are needed !
How does it work ?
The principle is quite simple : The EPS32 snifs the 1Wire protocol between the charger and the smart battery.
All the protocol has been reversed ingeneered by @AirCruiser .
A lot of information can be found on Discord channel as well.
And finally to stop the charge at the level I want , I simply pull down the 1Wire line, this breaks the connection between the battery and the charger. The battery disconnects and the charger goes to "fault".
Here an exploded view of the device:
I have coded a simple Android Application. It connects to the "SmartSmart" charger with Bluetooth Low Energy.
The device notifies all charging parameters via BLE.
The App simply displays these parameters as dynamic curves. It allows to send back the End of Charge level you want to stop the charge automatically.
You have access to:
- voltage (V)
- current (A)
- remaining Capacity (mAh)
- state of charge (%)
- temperature (°C)
- each individual voltage of the cells (V)
This charger has been running now for more than 6 months without issue.
IYou were many to ask for the source code.
So I decided to publish a "lite" version. Don't panic this version is fully functionning and has all the features excepted the Bluetotth communication to the Android App to monitor the charge.
But it has the most important : stopping the charge at 60% to protect your battery.
I do use this version everytime as monitoring the charge id fancy but useless in a dayly usage !
You can find the source code on my github page here: https://github.com/f2knpw/DJI_Avata_Smart_Smart_charger