Owners of the popular fitness tracker often face a situation where the device stops responding to connections or the charging indicator does not light up. Xiaomi Mi Band 4 is equipped with a built-in 135 mAh battery, which provides up to 20 days of battery life, but over time, energy saving efficiency can decrease due to improper operation. Understanding the principles of the lithium polymer battery and the design of the tracker will help extend the life of the gadget.
The specificity of charging the Mi Band 4 is that there is no familiar Micro-USB or USB-C connector on the body itself. All electronics are hidden inside the capsule, and a special connector located on the back of the tracker is used to transfer power. Inductive charging is not used in this model, so physical contact between the contacts of the capsule and the charger is critical for successful replenishment of energy.
In this article, we will discuss in detail the connection algorithm, possible causes of system failure and methods of resuscitation of the device at home. You do not need complex equipment or soldering skills, since most problems are solved by simply cleaning or replacing the cable. The correct approach to maintaining electronic contacts ensures stable operation of the tracker throughout its life.
Design of charger and capsule
To start charging, you need to remove the tracker from the silicone strap. Xiaomi Mi Band 4 consists of a main capsule and a removable bracelet that are connected by a tight fit. On the bottom of the capsule are two golden contacts that should perfectly match the response pins of the charging cable. The design is designed in such a way as to minimize the risk of moisture entering the interior when accidentally wet.
The charging cable is a USB-This holder has a shape that repeats the bend of the capsule, which allows you to securely lock the tracker during the procedure. There is no magnetic attachment in this model, so the fixation is solely due to a tight fit into the slots of the charging dock. Any shift may result in interruption of the process.
⚠️ Warning: Do not put excessive effort into inserting or removing the capsule from the charger.Mechanical pressure can damage the delicate contacts or lead to the formation of microcracks in the body.
There are several types of chargers for this model, including original cables and third-party counterparts. The build quality of cheap copies often leaves much to be desired, which leads to poor contact. The original accessory has strictly calibrated dimensions, ensuring perfect fit to the surface of the tracker.
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When buying a third-party cable, pay attention to the height of the pins – if they are too short, charging may not start due to lack of contact.
Step-by-step instructions for connecting to the network
The charging process of the Mi Band 4 is simple, but requires attention to the details of the connection. First, remove the tracker from the strap, gently pushing it out with your thumb on the inside. Then insert the capsule into the charger so that the contacts match. The battery icon should appear on the tracker screen, and the display will light up the current level of charge.
☑️ Connection check
Connect. USB-You can use a computer port, a laptop port, or a smartphone adapter, and it's important that the source delivers a standard 5 volt voltage. The use of powerful fast charging units from modern flagships is theoretically possible, since the power controller will limit current, but it is safer to use older adapters with current 1A or 2A.
Once connected, the indicator on the screen should be constantly on or flashing, signaling the process. Full charging takes about 2 hours. If the screen does not catch fire, try to slightly move the capsule in the holder or wipe the contacts. The contact group should be clean and dry for the electric current to pass.
- 🔌 Use only the correct ones. USB-cables without visible damage to insulation.
- 💧 Make sure the contacts on the capsule and cable are completely dry before connecting.
- 📱 For fast charging, it is better to use a smartphone adapter, not a weak PC port.
Why the bracelet is not charged: The main reasons
If you're connected to the grid, the screen is black and there's no vibration, it's not going to work. The most common reason is oxidation of the contacts. When you wear the gold pens, sweat, skin fat and moisture get on the gold pens, forming a non-conductive film, and this oxide film blocks the transfer of energy from the charger to the battery.
The second reason could be a deep battery drain, where if the tracker was off for several months, the voltage on the battery dropped below the start threshold of the controller, in which case the protection system blocks charging to prevent damage to the battery chemistry, and it takes time to rock the battery with low currents.
⚠️ Warning: If the bracelet has been in the cold for a long time, do not connect it to charging immediately.Let the device warm up to room temperature, otherwise the condensation inside can cause a short circuit.
It's also worth checking the integrity of the charging cable itself, and frequent bends cause the inner veins to break, especially at the junction point. USB-The wire may look whole visually, but there will be no electrical contact. Check the cable on another device or replace it with a known serviceable one.
How do you check the charging current?
Methods of cleaning and restoring contacts
To fix oxidation problems, you need to mechanically clean the contact group, take a cotton swab lightly soaked in alcohol or a special contact cleaner, carefully but with a little pressure, wipe the golden patches on the back of the capsule, the alcohol solution effectively dissolves fat deposits and removes oxides.
If a simple wipe didn't work, you can use a stationery eraser, you have to use a dry eraser to run the contacts several times, erasing the top oxidized layer, after this treatment, be sure to remove the residue of the rubber crumb with dry cloth, which often helps restore conductivity even on older devices.
| Cleaning method | Efficiency | Risk of damage | Recommended remedy |
|---|---|---|---|
| Dry fabric | Low. | Minimum | Microfiber |
| Alcohol wiping | Tall. | Low. | Isopropyl alcohol |
| Lasser | Medium | Medium (scratches) | White stationery eraser |
| Toothbrush | Medium | Low. | Dry brush |
After cleaning, let the contacts dry for 1-2 minutes. Don't connect the wet device to the network. If after all the charging procedures have not started, perhaps the problem lies deeper - in the battery itself or the power controller, in which case hardware diagnostics is required at the service center.
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90% of charging problems are solved by cleaning the contacts thoroughly with alcohol and eraser.
Recovery after deep discharge
When the Mi Band 4 was idle for a long time, the battery could go into “sleep mode,” in which the charge controller blocks the input current. To “wake up” the battery, you sometimes need to leave the device on charge for a long time — from 30 minutes to several hours. The screen may not light up immediately, but inside will be a slow process of energy storage.
There is a shock charging technique that helps start the process: connect the tracker to a powerful power source (for example, a USB 3.0 port of a computer or a 2A adapter) for only 5-10 seconds, then turn off and reconnect. Repeat the cycle 3-4 times, which can help raise the voltage at the battery terminals to the level necessary to activate the controller.
- ⏳ Leave the device on charge on 2-3 Even if the indicator is not on.
- 🔄 Try to reconnect the cable several times. USB-port.
- 🌡️ Warm the back of the capsule (not above 40)°C) to improve the chemical reaction in the battery.
If none of these methods worked, it's likely that the battery is exhausted or out of order. Lithium polymer batteries degrade over time, even without use. Replacing the battery is possible, but requires soldering iron skills and accuracy, because the battery is glued to the board.
Technical specifications and working time
Xiaomi Mi Band 4 is equipped with a Li-Po battery with a rated voltage of 3.7 V. The capacity is 135 mAh, which is the optimal balance between size and autonomy. In moderate use, when notifications come infrequently, and sleep and heart rate monitoring is on, the device lasts up to 20 days. Active use of GPS (via phone) and constant illumination reduce this time.
The charge rate is relatively low. A full cycle of 0 to 100% takes about 1.5-2 hours. The charge controller automatically reduces current in the final stage (recharging mode) to prevent overcharging and swelling of the battery. Therefore, leaving the tracker on charging overnight is not recommended, although modern controllers have protection.
⚠️ Warning: Do not use homemade chargers or connect contacts directly to batteries, this will cause the electronics to fail and possible fire.
To extend the battery life, try not to discharge the device to zero regularly. The optimal range of lithium batteries is from 20% to 80%. If you plan not to wear the tracker for a long time, charge it to about 60% and turn it off. You absolutely can not store a fully discharged device.