EV owners often experience a situation where the electric scooter stops correctly displaying the charge level or suddenly turns off on a full battery. These are classic symptoms of desynchronization of the controller software with the real state of the battery cells. For the Xiaomi M365 model and its modifications (Pro, 1S), this problem is solved by a software reset BMS (Battery Management System).
Incorrect control system operation can lead to the fact that the device will go into a deep discharge, which is critical for lithium-ion cells. That is why timely calibration or resetting of BMS is a necessary preventive measure. In some cases, users try to roll back the firmware version to the older version to return the functionality that was stripped down in new updates from the manufacturer. Below we will discuss the technical details of these processes.
It is worth noting that interference with the controller's code always carries certain risks. Mistakes can lead to device locking or, in the worst case, to failure of electronic components. So before starting any manipulations, make sure that you fully understand each step. The process of resetting the BMS irreversibly erases charge cycles and error history, which can affect the residual cost of the device when resold.
Diagnostics of the controller and battery status
Before taking drastic measures, it is necessary to accurately determine the nature of the malfunction. Often users confuse a software failure with physical wear of the battery. If your Xiaomi M365 shows 50% charge and then abruptly turns off, this is a clear sign that the controller has “forgot” the real capacity of the cells, in which case a software reset can revive the device without replacing expensive components.
Accurate diagnosis will require a Bluetooth connection to the scooter using specialized mobile applications. The standard Mi Home app often hides the detailed technical information needed for deep analysis. You will need third-party utilities such as Xiaomi Flasher or DashBoard that allow you to read raw data from a BMS. This data includes the voltage of each cell group, temperature and number of cycles.
⚠️ Note: If the voltage difference between individual cell groups (balancing) exceeds 0.3-0.5 Volta, software reset can be dangerous, so you need to balance the battery first.
Error log analysis also helps to understand whether a full reset or a simple enough calibration is required. Xiaomi controllers write down error codes that can be decrypted. For example, frequent overdischarge errors may indicate that BMS prematurely turns off power, believing the battery is empty, although there is still energy, this is treated by flashing or resetting BMS parameters.
Visual inspection of connectors and wires is also mandatory. Oxidation of contacts or broken Hall sensor wire can give symptoms similar to software failure. Make sure all connectors are tightly seated in their nests. Only after eliminating mechanical damage can you move to the software part.
To successfully perform the procedure, you will need a certain set of tools and software. Without a specialized adapter (often called a “whistle” or dongle), you will not be able to connect your computer to the scooter, since the standard charging port is not designed to transfer firmware data in DFU mode. The adapter usually has XT60 connectors or a specific 3-pin connector.
Besides hardware, it's critical to have a software environment in place. You'll need a Windows PC, because most of the firmware snails (Xiaomi Flasher, M365 Tools) are built for this platform. You'll also need to install drivers for the UART-USB converter that's used in the adapter. Without the right drivers, the computer won't see the scooter controller.
Don't forget to take safety precautions. Work is best done in a dry room at room temperature. High humidity or frost can adversely affect the process of writing data to the controller's non-volatile memory. It is also recommended to have a multimeter on hand to monitor voltage on contacts in real time.
The list of required software usually includes:
- 🔌 Drivers for UART-USB bridge (CH340, CP2102 or FTDI).
- 💻 Utility for firmware (for example, Xiaomi Flasher or analogue).
- 📄 Firmware files (.bin) of the corresponding version for your model.
- 🔋 Battery monitoring software (optional, but desirable).
BMS reset procedure and battery calibration
The very discharge process BMS (Battery Management System is a key step in restoring the battery to a correct function, which causes the controller to remeasure the capacity of each cell and reset the cycle counter. USB-If you connect correctly, the adapter should light up the indicator, and a new Windows Device Manager will display a new indicator. COM-port.
Start a program to work with BMS. In the interface, select the appropriate COM-Then press the connection button. If the connection is successful, you'll see the current battery settings: voltage, current, temperature and cell status «BMS» or "Settings" and select the Reset option BMS Or "Clear Flags." Once confirmed, the controller will rewrite its internal registers.
What happens when a BMS is dropped?
When discharged BMS The controller forgets the history of charge-discharge cycles and drops error flags (e.g. overcharging or overheating error) to wake up a battery that has gone into defense, but does not treat physically dead cells.> After the program reset, be sure to perform a calibration procedure. To do this, fully charge the scooter to 100% (until the charger indicator lights up green), and then completely discharge it during the ride until completely switched off. This cycle helps the controller to build a new discharge curve that accurately determines the percentage of charge in the future. It is important not to interrupt the charging and discharging process during calibration. If you interrupt charging by 90%, the controller can start to miscalculate again. Full cycles "to zero" and "to the end" are necessary for synchronization of voltmeter readings BMS and the actual chemical state of lithium cells. Many users prefer to return old firmware versions, as new updates from Xiaomi often limit maximum speed or turn off recovery mode at low speeds. The downgrade process is technically similar to an upgrade, but requires an old firmware file (.bin) to be found and saved on your computer in advance. New versions of the software often block the possibility of rollback, so you need to proceed carefully. DFU (Device Firmware Update. Put the scooter into this mode by holding the brake and the gas trigger, and then turning on the power (the indicators must blink in a specific way). Connect the adapter and start the firmware utility. Select the old firmware file and press "Flash" or "Update." The process takes about 1-2 minutes during which you cannot touch the scooter. Version of the firmware Features Recommendation 1.3.4 / 1.4.2 Classic versions, no regional restrictions Recommended for enthusiasts 1.5.x Added support for new accessories Stable version 1.6.x And above, Enhanced Protection, Region Locking Officials Only After a successful flashing, the scooter can beep or blink headlights. Check the version in the Mi Home app - it must match the one you filled. If the device is not turned on, it is possible that the firmware file was damaged or not suitable for auditing your controller (for example, firmware from the computer). M365 Install custom firmware and modifications for advanced users who want to unlock the hidden potential of Xiaomi M365, There are custom firmwares that allow you to change the recovery current, remove the speed limit. 25 km/h 30+ km/h) and change the logic of the headlamps. But installing this software requires a deep understanding of the risks. BMS, This is a very simple system that, if used in a careless manner, will overheat. DFU. You select a custom firmware file (often modified versions of official bin files) and upload it to the controller, and once installed, it is recommended to immediately check the operation of all systems: braking, gas, indication. Any strange behavior should be a signal for the immediate return of stock firmware. ⚠️ Attention: Installing custom software will void warranty, and improperly configured recovery can cause the controller to overheat and burn up when braked frequently on the slopes. Pay special attention to regenerative braking settings. In the drain, it's set up conservatively for safety. Increasing the recuperation current makes braking more sharp and efficient, but puts a lot of stress on the battery. If your battery is old or has high internal resistance, aggressive recovery can cause a voltage drawdown and an emergency shutdown of the scooter on the go. Frequent errors and fixes: In the process of resetting or firmware, users often encounter typical problems. One of the most common is Connection Failed, or connection timeout, which usually means that drivers are installed incorrectly, the wrong one is selected. COM-port or contact in the charging connector is oxidized. Try reconnecting the cable, using another USB-port (preferably) USB 2.0) or reinstall the drivers. Another common error is "Flash Failed" or interruption of the process in the middle. If the power of the scooter sits down or the cable departs during recording, the controller can "brick" in this case, only the reconnection of contacts on the controller board to force the bootloader mode (Bootloader), which requires dismantling the deck and the presence of a soldering iron, will help. 💡Use a Uninterruptible Power Supply (UPS) For a laptop, or make sure that the laptop is fully charged, a power surge or battery drain on the PC during firmware can fatally damage the scooter controller. BMS The scooter behaves strangely (twitches at start, mischarging), try to perform the full calibration described above. 2-3 So you can take a full charge-discharge cycle to stabilize the algorithms. You can't jump to conclusions after the first trip. In the case of persistent errors that don't go away after the reset, the problem is probably hardware. It could be a faulty Hall sensor in the motor wheel, a phase break, or degradation of one of the cells in the battery, and the software methods are powerless, requiring multimeter diagnostics and possibly replacement of components. 💡Successful resetting of firmware and BMS returns the scooter to the factory accuracy of the charge readings, but is not able to restore physically worn lithium cells. FAQ: Frequently Asked Questions Is It Safe to Reset BMS If you follow the instructions and use the equipment properly, the risk is mainly that the controller will break down when the process is interrupted, not that the user will be physically harmed if the battery is not disassembled. Will the scooter lose its run after flashing? Usually, the total mileage is stored in a separate memory cell and is not erased when you update the firmware. BMS drop-off. Some custom tools allow editing and mileage, but it requires separate manipulations. M365 Pro firmware from the regular version? categorically not recommended. BMS version M365, Pro and 1S They have differences in hardware and algorithms. Filling incompatible firmware can cause the security system to malfunction or the device to fail completely. Do you need a special adapter to reset, or will Bluetooth be enough? For a conventional air upgrade (OTA) It's not enough Bluetooth, but it's for deep reset. BMS, Reading logs and rollback versions are required special UART-USB Adapter ("whistle") connected to the charging port, as these functions are hidden from the standard wireless protocol.