DJI battery sleep mode

got a CP2112 board and to “wake up” battery, by clearing the BMS failure flags(there are plenty information on how to do this on the web – this linkexample). Managed to connect to the batteries using the CP2112 board(had to give the battery external 9v power to do it), but was unable to clear the flags. It looks like the BMS was unhappy with one of the cells on each battery – they had drained below 2V.

Since the bad cells on both batteries were around 1.7V-1.9V, witch is not good for a LiPo cell, but is also not necessarily a dead cell, so I decided to try and save some money and try to restore them.

The next issue was that these are Intelligent Batteries – they have BMS that controls the charging and balancing the cells, unlike other dumb LiPo batteries I have used, where the charger is the responsible for the cell balance.

So I opened up one of the “dead” batteries and checked the cells. Good news – no swelling.

DO NOT MESS SWOLEN LIPOS – dispose of them safely. You dont want to burn your place down or injure yourself.

Measured the voltage on on the terminals of each cell and confirmed that one was around 1.7V.

Now I had to bypass the BMS and use a balance charger in “dumb” LiPo charge mode(not balanced) to give it some juice.

Used alligator clips to connect to the the end terminals for the LiPo pack and set the charger to a LiPo 3 cell – 11.1V. I set the power at 0.5A.

I had to pry the back plate a bit to get to the negative terminal

My charger didnt like that the battery voltage was below 8V and didnt want to charge it.

Changed the setting to a 2S battery and this did work – the batter charged for couple minutes before the charger turned off, but that was enough for it to be detected as a 3S battery. Ten I charged the battery for about 20 minutes on the 3S setting and disconnected it.

Put the battery back together and connected it to the CP2112 board again. Gave it 9V from an external source and it read the info from the BMS – cells were looking good and pretty balanced compared to before and this time I was successful at unsealing the battery, cleaning up failure flags and resetting the chip.

And best of all it started charging on the DJI charger.

Did the same with the second battery and it worked too, so that was pretty nice.

What is left to do:

  1. Leave the batteries alone for couple days after charging and check the cell balance after that.
  2. If the cells are still balanced, wait for the weather to clear up and fixed batteries and compare them to the known good one, having in mind that they might need few cycles to fully stabilize the bad cells.

Another way

How to Fix Dead DJI Drone Batteries Using Battery Killer and CP2112

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If you’re facing problems like your  batterynot charging, overheating, or needing firmware updates, we’ve got you covered. From  Mavic Mini to Inspire 1 and Phantom, we’ll provide practical solutions and DIY tips. Learn about battery storage, maintenance, and specific fixes for different  dronemodels

In this post, we’ll discuss a software solution for dealing with BMS (Battery Management System) issues by resetting power failure flags, also known as flags. When a power failure is detected, the BMS shuts down to protect the battery. This can happen if the power drops below a specific limit or if you disconnect the cells.

We will walk you through an easy and effective drone repair method using the DJI Battery Killer and CP2112 Adaptor that can save you from purchasing expensive replacement batteries.

Say goodbye to battery charging problems, overheating, and more. Get your drone back in the air with this simple and effective repair method. Let’s get started on getting your drone back in the sky🛠️🔋🚀

Understanding DJI Intelligent Batteries

DJI drone batteries are considered Intelligent Batteries because they have advanced features like a Battery Management System (BMS) that monitors key parameters like voltage, temperature, battery health, communication with the drone, safety mechanisms, hibernation mode, and optimized design.

Required Tools and Materials

Before starting the repair process, make sure you have all the necessary tools and materials:

  1. CP2112 USB-to-I2C adapter (Amazon.com / Aliexpress)
  2. Jumper wires (Amazon.com / Aliexpress)
  3. Adjustable power supply ( up to 16V) (Aliexpress)
  4. Dead DJI battery
  5. Micro USB cable (Aliexpress.com)
  6. Small screwdriver set (only needed for Mavic Pro batteries)

Common DJI Battery Problems and Symptoms

Before attempting repairs, it’s important to identify the symptoms your battery is experiencing:

  1. Battery Not Charging – The battery won’t accept a charge, or the charger shows error lights
  2. Battery Not Recognized – Drone doesn’t recognize the battery when inserted
  3. Rapid Discharge – Battery drains much faster than normal
  4. LED Indicators Flashing Abnormally – Error patterns on the battery LEDs
  5. Overheating – The battery becomes unusually hot during charging or use
  6. Sudden Power Loss – Drone suddenly loses power during flight
  7. Battery Swelling – Physical swelling or deformation of the battery (requires immediate attention)

This guide primarily addresses software-related issues with the BMS. If your battery shows physical damage or swelling, do not attempt repair and dispose of it properly.

Battery Specifications

DJI Mavic Air Battery Specs and Pinout

DJI Mavic Air Battery Specifications

  • Capacity: 3500 mAh
  • Voltage: 11.55V
  • Energy: 40.42 Wh (typical value)
  • Battery Type: LiPo 3S
  • Charging Voltage Limit: 13.2 V
  • Discharge Temperature: -10° to 60 °C (14° to 140° F)
  • Charge Temperature: 5° to 40 °C (23° to 113° F)
  • Charging Time: Approximately 55 minutes (using a DJI charger)
  • Weight: 140 grams
  • Compatibility: Designed specifically for DJI Mavic Air drone

DJI Mavic Air Battery Pinout

  1. Positive Terminal (+)
  2. Negative Terminal (-)
  3. SDA (Serial Data)
  4. SCL (Serial Clock)

Buy DJI Mavic Air Battery From Aliexpress.com

DJI Mavic Mini Battery Specs and Pinout

DJI Mavic Mini Battery Specifications:

  • Model: BWX161-2250-7.7
  • Nominal Capacity: 2250 mAh
  • Battery Type: LiPo 2S
  • Nominal Voltage: 7.7 V
  • Charging Voltage Limit: 8.8 V
  • Charging Temperature: 5 °C to 40 °C (41 °F to 104 °F)
  • Maximum Charging Power: 29 W
  • Applicable Model: DJI Mini 2S Drones

DJI Mavic Mini Battery Pinout

Buy DJI Mavic Mini Battery from Aliexpress.com

CP2112 Adaptor – USB to I2C Debug Board

The CP2112 Adaptor is a USB-to-I2C (Inter-Integrated Circuit) debugging board that serves as an interface between a USB-enabled computer and I2C devices. It acts as a bridge, allowing the USB host to communicate with I2C devices using a USB-to-I2C data protocol.

CP2112 configures communication and host control between the computer and the target device, such as the DJI drone battery. Connecting the CP2112 Adaptor to a computer’s USB port allows users to access and communicate with I2C devices, read and write data, and send commands.

CP2112 Adaptor Pinout

  1. VCC: Power supply voltage.
  2. GND: Ground.
  3. SDA: Serial Data Line
  4. SCL: Serial Clock Line
  5. WAK: Wake-up pin
  6. INT: Interrupt pin
  7. RESET: Reset Pin.

The CP2112 acts as an interface between your  computer and the  battery’s BMS. It communicates with the BMS via SDA and SCL connections. The BMS is designed as a safety feature to safeguard both the user and the battery in case of power failures, disconnections, or short circuits.

 Battery Repair Process

Connection Setup

To connect the interface to the battery, connect the ground pin of the interface chip to any negative terminal of the battery. Connect the SDA and SCL pins to their respective points on the battery terminal.

Step-by-Step Connection Process:

  1. Identify the battery’s pinout (refer to the pinout diagrams above).
  2. Connect the GND pin of the CP2112 Adapter to the battery’s negative terminal.
  3. Connect the SDA pin of the CP2112 Adapter to the SDA pin on the battery.
  4. Connect the SCL pin of the CP2112 Adapter to the SCL pin on the battery.
  5. Double-check all connections before proceeding.

Software Setup and Battery Unlocking

This program has been developed to unlock DJI Mavic batteries with bq9003 (bq40z307) chips using the reliable CP2112 HID USB to SMBus/I2C adapter.

Download DJI_Battery_Killer

Step-by-Step Software Process:

  1. Connect the CP2112 adapter to your Windows computer using a micro USB cable.
  2. Open the Battery Killer software.
  3. Click on “Connect” to establish a connection with the battery.
  1. If the connection is successful, the software will communicate with the BMS.
  2. Click on the “Read Info” button to retrieve the battery information. You should see detailed battery data like this:
12345678910Device successfully openedDevice successfully configured(00) Manufacturer Access = 0x300(01) Remaining Capacity Alarm = 44 mAh(02) Remaining Time Alarm = 10 min(03) Battery Mode = 0x6001(04) At Rate = 0 mA…(D8) DJI Battery S/N : 0P2AFB553408ER
  1. Now, follow these specific steps to unlock the battery:
    • Click on the “Unseal” option to remove the seal on the battery.
    • Click on “Clear PF” to clear any power failure flags.
    • Click on “Clear PF2” to clear additional power failure flags.
    • Finally, click on “Reset Chip” to reset the battery’s BMS.
  1. After completing these steps, disconnect the CP2112 adapter and test your battery with a charger.

Troubleshooting Common Issues

Connection Problems

  • CP2112 Not Detected: Ensure proper USB connection and driver installation
  • Communication Failure: Double-check the SDA and SCL connections
  • Read Info Failure: Make sure the battery has some charge (at least 10%)

Software Issues

  • Unable to Unseal: Try reconnecting and repeating the process
  • Clear PF Failure: Ensure the CP2112 adapter is connected correctly
  • Battery Not Responding After Reset: Wait 5 minutes and try again

Post-Repair Issues

  • Battery Still Not Charging: Verify cell voltages are within acceptable ranges.
  • Battery Not Recognized by Drone: Try a firmware update on the drone
  • Rapid Discharge: Battery cells may be damaged and need replacement

Battery Maintenance Tips

To prevent future battery issues and extend the life of your DJI batteries:

  1. Store at 40-60% charge when not in use for extended periods
  2. Store in cool, dry places (10-25°C/50-77°F)
  3. Avoid full discharges whenever possible
  4. Use only official DJI chargers
  5. Check for firmware updates regularly
  6. Allow batteries to cool after flights before charging
  7. Perform regular discharge/recharge cycles (once every 20 cycles)
  8. Inspect for physical damage before each use

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