Fitness tracker Xiaomi Mi Smart Band 4C Black (model) MGW4067RU) It has become one of the most popular gadgets for monitoring activity due to the combination of affordable prices and advanced functionality. However, many users are faced with questions about the correct charging of the device - especially if it is a question of first recharging or restoring a discharged battery, 4C-The version has unique features in the connector design and power management algorithm, which requires a separate analysis.
In this article, we will discuss how to charge the Mi Band. 4C, To avoid the typical mistakes, from choosing a charger to diagnosing battery problems, you will learn why the tracker may not turn on after connecting to the network, how to properly store the gadget without losing battery capacity, and what to do if the charging indicator does not burn. Particular attention will be paid to hidden functions that the manufacturer does not advertise - for example, forced reset of the power controller when the process "hangs.
Technical characteristics of the Mi Band battery 4C
Before you get to the instructions, it's important to understand what type of battery you're dealing with. - Xiaomi Mi Smart Band 4C Black is equipped with a lithium polymer battery capacity of 135 mAh, which is 10% more than the base model Mi Band 4. This allows the device to work for up to 14 days in standard use (with sleep monitoring and notifications enabled). However, the actual life of autonomy depends on several factors:
- 🔋 Phone sync frequency (every 5 minutes vs. 1 hour)
- 📱 Screen activity (number of hand lifts to view time)
- 🏃 Use of the GPS (When connecting to a smartphone for tracking jogs)
- 🌡️ Ambient temperature (optimum: 10-35)°C)
Power Controller in the Mi Band 4C supports fast charging to 80% post 50 minutes, but the full cycle takes about 2 Important: the device uses a proprietary magnetic connector with 2 Contacts (not compatible with Mi Band charging) 5/6). Attempting to charge a tracker from another device can damage the contacts or controller.
| Parameter | Meaning | Note |
|---|---|---|
| Type of battery | Li-Po (lithium-polymer) | No memory effect, but sensitive to deep discharge |
| Capacity | 135 mAh | 10% more than the standard version of the Mi Band 4 |
| Nominal voltage | 3.85 In | Maximum 4.35 V (controlled by built-in control) BMS) |
| Charging current | Up to 150 m. | Automatically limited by the controller |
| Term of service | 300-500 cycles | Up to 20-80% (recommended range) |
One of the little-known facts: Mi Band 4C It has built-in overcharging protection, but is not protected from a deep discharge below 2.7 V. If the tracker has been discharged for more than a month, you may need to "resuscitate" through a special adapter with increased current.
Completement and original charger
In the box with Xiaomi Mi Smart Band 4C Black you'll find:
- 📦 The fitness tracker itself (module with screen)
- 🔌 Magnetic charger with cable USB Type-A
- 📄 Short instructions (without charge details)
- 🔄 Rubber strap (already installed on the module)
The original charger has two key features:
- Magnetic fixation: The contacts are automatically attracted to the connector on the back of the tracker, and if the magnet is weakened, it is a sign of a fake.
- LED-indicator: red is charging, green is charging completed. Lack of indication may indicate problems with the cable or battery.
⚠️ Note: Many users confuse charging from Mi Band 4C accessories for the Mi Band 5/6. Visually, they're similar, but they have different polarity of contacts:
- ⚡ Short circuit (if the contacts are closed)
- 🔥 Overheating of the power controller
- 📉 Rapid wear of the battery (due to improper current)
If you lost the original charger, look for a replacement with a marking MDY-11-EM (Manufacturer's article: alternatives must be:
- 🔌 Jack USB Type-A (not Micro-USB!)
- 🧲 Magnetic attachment force of at least 0.3 N
- 🟢 Charging indicator (required!
There is a Xiaomi logo on the body|
The magnet securely fixes the tracker|
The indicator lights up red when connected|
The cable is flexible, without fractures at the base-->
Step-by-step instructions for charging Mi Band 4C
The charging process seems simple, but there are nuances that affect battery life.
- Disconnect the strap (optional): if the tracker is tightly seated in the bracelet, you can charge without removing it.
- Connect the charger to the power source: 💻 USB-port (500 Ma, slow down) 🔌 Network adapter 5V/1A (optimally) ⚡ Fast charging. 5V/2A (Acceptable but not expeditious process)
- Connect the tracker to the magnetic connector: 🔄 Contacts must match the labels on the body (see photo in spoiler) 🧲 Make sure the magnet is “clicked” – this means that the connection is reliable.
- Check the indication: 🔴 Red light - charging is coming 🟢 Green light – charging is complete (can be turned off) ⚫ No lights – check the cable or port USB
⚠️ Attention: if the tracker has been completely discharged (the screen is not turning on), it may take 10-15 minutes for the charging indication to appear. This is normal - the controller needs time to initialize!
Optimal charging time:
- 🔋 0–80%: ~40 minutes.
- 🔋 80–100%: ~40 minutes (slowed down to protect the battery)
- ⏱️ Full cycle: up to 2 hours
Do not leave the tracker on charging for more than 3 hours - despite the protection against overcharging, a long connection to the network can lead to heating of the controller.
How to properly place the tracker on charging?
Common Mistakes and How to Avoid Them
Even experienced users sometimes make mistakes that shorten battery life or make the tracker fail, and here are the most common problems and solutions:
1.The tracker is not charged (the indicator is not lit)
Causes and solutions:
- 🔌 Bad contact: clear the tracker contacts and charge with an alcohol napkin. Sometimes it helps to lightly press the module while connecting.
- 🔋 Discharged below critical level: connect to source 5V/2A and wait 15–20 If the indicator does not appear, "resuscitation" is required (see next section).
- 🔌 Cable damaged: check the integrity of the wire, especially at the base of the connector.
- 📱 The port problem USB: Try another port or charger.
2.The tracker is charging too long
If the process takes more than 3 hours, the probable causes are:
- 🐢 Weak power source: USB-The computer port can only give you 100-300 mA. Use a network adapter.
- 🔥 Overheating: if the tracker is hot, turn it off for 10 minutes. Charge at temperatures above 40°C automatically slows down.
- 🔋 Worn-out battery: if capacity falls below 60% of face value, charging time increases.Check battery status in the Mi Fit app.
3.The tracker discharges quickly after charging
This may be related to:
- 📲 Background: Turn off unnecessary notifications in Mi Fit (such as weather or social media messages).
- 🔄 Frequent synchronization: set the data update interval no more than 1 time per hour.
- 🏃 Permanently GPS-Tracking: If you are not running, turn off this feature in the settings.
- 🔋 Battery defect: if the tracker holds the charge for less than a day, a battery replacement is required.
⚠️ Warning: if the tracker is 100% after full charging, but suddenly drops to 20% after an hour, this is a sign of a malfunction of the power controller.
💡
If the tracker doesn't respond to charging, try resetting it to factory settings. To do this, plug it into charging, then press and hold the touch button for 10 seconds until the Xiaomi logo appears.This will reset the settings, but will not affect the activity data (they are stored in the app).
How to “resuscitate” a completely discharged tracker
If you're a Mi Band 4C It was uncharged for more than a month, and its battery could run out to a level where the controller would block charging. USB It won’t help, we need an alternative method.
You'll need:
- 🔌 Charger from Mi Band 4C (original)
- 📱 power supply 5V/2A (for example, charging from a smartphone)
- ⏱️ Patience (the process can take up to 1 hour)
Algorithm of action:
- Connect the charger to the power source.
- Attach the tracker to the magnetic connector and hold it with your hand for 30 minutes, even if the indicator is not on.
- After 30 minutes, turn off and reconnect the charger. Repeat step 2.
- If the indicator does not catch fire after 1 hour, try using another cable or adapter.
If this method does not work, there are two options:
- Use a universal charger with adjustable voltage (for example, iFixit Mako Drive), setting the parameters: Voltage: 4.2 In Current: 100 mA Polarity: plus top, minus bottom
Contact the service center
800 to 1500 rubles
⚠️ Warning: Don't try to disassemble the tracker yourself! - Mi Band body 4C It's glued with ultrasonic welding, and you're at risk of damaging the screen or the board if you're still in the warranty (12 months), the repairs will be free.
💡
If the tracker doesn't show signs of life after all the manipulations, check it on another charger. In 30% of cases, the problem lies in the faulty cable, not in the gadget itself.
Tips for extending battery life
Lithium polymer batteries in fitness trackers degrade over time, but proper use can increase their lifespan by 30-50%.
Optimal charge level
Avoid extremes:
- 🔋 Don’t discharge below 20%: Deep discharges shorten lifespan.
- 🔌 Don’t hold 100% longer than 2 hours: High voltage accelerates degradation.
- ⚡ Ideal range: 30-80% (unless you need maximum autonomy).
Temperature conditions
Extreme temperatures are harmful to the battery:
- ❄️ Cold (below 0)°C: temporarily reduces capacity, but recovers when heated.
- 🔥 Heat (over 40)°C: irreversibly damages the chemical composition of the battery.
- 🌡️ Optimal: 10-35°C (room temperature).
3. Regular use
If you don’t wear a tracker all the time:
- 🔄 Charge up to 50% before storage.
- 📅 Turn on once a month and discharge/charge to 40-60%.
- 🏠 Store in a dry place, avoiding direct sunlight.
4.Settings for energy savings
Turn off unnecessary features in the Mi Fit app:
- 📱 Notifications from unnecessary applications.
- 🌙 Automatic sleep monitoring (if not required).
- 🏃 Continuous pulsemeter (replace by manual start).
- 🔍 Phone search if you rarely use it).
Following these tips, you can extend the life of the battery to 3-4 years instead of the standard 1.5-2 years. Remember: even if the battery capacity has decreased, the tracker remains usable - you just have to charge it more often.
Alternative ways of charging (in extreme cases)
If the original charger is lost or broken and it takes time to buy a new one, alternative methods may be used, but they do come with risks – use them only in emergency cases!
1. Charging from Power Bank with magnetic adapter
Some external batteries (e.g. Xiaomi Power Bank 3) have an output. USB Type-A, you can:
- Connect charging from Mi Band 4C Power Bank.
- Make sure the output current does not exceed 2A.
- Control the process – not leave unattended.
2.Use of a universal charging station
Devices like the Nillkin Magic Disk have interchangeable magnetic attachments. 4C adapter:
- 🔌 Connector. 2-pin (two-way).
- 🧲 Magnetic fixation.
- 📏 Distance between contacts 4.5 mm.
⚠️ Attention: universal charging may not comply with the original current and voltage parameters:
- 🔥 Overheating of the power controller.
- 📉 Rapid battery degradation.
- ⚡ Short circuit with incorrect polarity.
Homemade adapter (for power users)
If you are familiar with electronics, you can weld an adapter from:
- 🔌 Connector USB Type-A (donor).
- 🕒 Two magnets 3 mm in diameter.
- 🔋 Resistor 100 ohms (to limit current).
Connection diagram:
USB 5V+ ---[Resistor 100 Ohms]--- Upper Contact (plus)
USB GND -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------⚠️ Warning: This method requires soldering skills and an understanding of electrical circuits.A mistake in polarity or current will cause permanent damage to the tracker!