Xiaomi Redmi 4X, released in 2017, is still popular due to its reliability and autonomy. However, standard internal storage of 16 or 32 gigabytes for a modern user is often not enough to install applications, music and high-resolution photos, which is why the issue of expanding memory with external drives is especially acute for owners of this model.
Choosing the right memory card is critical to the performance of the Android system installed on board the device. Using an inappropriate or poor-quality drive can lead to interface freezes, slow loading of the gallery and even loss of important data. In this article, we will discuss in detail the technical specifications of the slot, supported formats and give recommendations for choosing the optimal solution.
Developers from Xiaomi have laid in this model quite flexible opportunities for upgrades, but with certain limitations, typical for Qualcomm Snapdragon processors of that period. Understanding these nuances will help you avoid buying unnecessary equipment and ensure stable operation of the gadget for a long time.
Technical characteristics of the microSD slot in Redmi 4X
The smartphone’s hardware platform is based on the Qualcomm Snapdragon 435 chipset, which determines the logic of the memory controller. The memory card slot is microSD and located on the left side of the case, hidden under a plug. Structurally, this is a separate connector, not combined with a slot for SIM-cards, which is a great advantage over many modern models, where you have to choose between the second SIM and flash drive.
Official documentation and specifications indicate support for cards up to 128 gigabytes. However, practice shows that the device can work correctly with more capacious drives, if they are formatted into the correct file system.
⚠️ Attention: The physical size of the card must strictly conform to the microSD format. SD through an adapter without a special adapter-extender can damage the contacts inside the slot.
The speed of reading and writing data is limited by the capabilities of the interface, which in this model complies with the UHS-I standard. This means that buying ultra-high-speed professional-grade cards (for example, the V90 series) will not give performance gains, since the smartphone controller simply will not be able to use their potential.
Supported volumes and file systems
Although the box and instructions often feature the number 128 GB, this limitation is due to the fact that at the time of the release of the smartphone, larger cards simply did not exist in mass production. Tests enthusiasts confirm that Redmi 4X successfully recognizes and works with cards with a volume of 200 GB and even 256 GB. The key point here is not the physical volume, but the file system.
Android defaults to external drives in FAT32 format. This file system has a limit on the size of a single file — it can not exceed 4 gigabytes. If you plan to store high-resolution movies or heavy archives on a flash drive, you will need formatting in exFAT.
- ⚙️ NTFS — natively not supported without root rights and installing special drivers, not recommended for normal use.
The formatting procedure in exFAT is usually performed automatically by the system when you first connect if the card is new, or through the settings menu. → Warehouse → SD-map → Format. The system will then suggest that you choose the format you want if the current format is not suitable for the planned operations.
Why does the system write"SD-map damaged"?
UHS Speed Classes and Standards
For a comfortable interface and running applications from a memory card (Adoptable Storage function), not only capacity is important, but also write speed. The Snapdragon 435 processor does not have high performance, so a slow card can significantly "hang" the system. The minimum required standard is the Class 10 speed class.
More modern designations, such as the U1 and U3, indicate minimum guaranteed recording speeds. U1 (10MB/s) is enough to record video in Full HD, but if you plan to shoot 4K video (although the Redmi 4X camera shoots a maximum of 1080p) or run heavy games from a flash drive, it is better to focus on the U3 class (30MB/s).
Also, look for A1 or A2 (Application Performance Class) tags, which are optimized for application use, providing faster access to random data blocks. For external storage, an A1 icon is desirable, although not strictly mandatory.
💡
When buying a memory card, pay attention to the availability of protection against counterfeiting. Buy products only in official stores or from trusted partners of the brands SanDisk, Samsung, Kingston, as the market is full of fakes with an understated real speed.
Using cards without a speed class (often labeled as Class 4 or no labeling at all) will cause the camera to interrupt recording and the photo gallery to load the preview of images for a long time.
Installation and formatting instructions
The process of installing the memory card in Xiaomi Redmi 4X is as simple as possible. You will need only the card itself and perhaps a clip to extract the tray, although in this model the slot does not require a key. Place the smartphone with the screen down, find an elongated stub on the left side. Carefully tuck it with a nail or a thin tool in a specially designated recess.
Put the memory card down to the typical click. Put the plug in place. Once turned on, the device should automatically notify you of a new drive. If that doesn't happen, check the density of the contacts.
☑️ Verification of the installation of a memory card
For initial settings go to the Settings menu → Storage, press the point. SD-Here you'll see the current status and the actions available, and if the map is new, the system will prompt you to format it. Select “Use as portable storage” if you want to store photos and music there, or “Use as internal storage” to expand the memory for installing applications.
⚠️ Note: When you select the internal storage mode, the card will be formatted and encrypted, and then it will not be read on other devices (PCs, other phones) without completely resetting and losing data.
Comparison of popular memory card models
To make it easier to choose, we have compiled a table comparing popular models that have performed well in tandem with mid-range Qualcomm processors, which will ensure stable operation without overheating or crashing.
| Model map | Class speed | Max, reading speed. | Optimal for |
|---|---|---|---|
| SanDisk Ultra | Class 10 / U1 | up to 100 Mb/s | Photos, music, documents |
| Samsung EVO Plus | Class 10 / U3 | up to 100 Mb/s | Full HD video recording, games |
| Kingston Canvas Select | Class 10 | up to 80 Mb/s | Basic file storage |
| SanDisk Extreme | Class 10 / U3 / A2 | up to 160 Mb/s | Heavy apps, 4K video |
As you can see from the table, there is no point in overpaying for the top Extreme models for the Redmi 4X unless you plan to record video from an action camera. The best choice for price-performance ratio will be SanDisk Ultra or Samsung EVO cards of the usual level.
Note that card speed can be reduced by more than 80-90% when filled, and it is recommended to leave free space for the correct operation of the file system and mechanisms for aligning the wear of memory cells.
Typical problems and ways to solve them
Despite the reliability of the model, users may encounter a number of problems when using external drives, often when the phone stops seeing the card after a system update or prolonged downtime, in most cases this is solved by software.
One common cause of failure is the use of cards recovered after a breakdown (so-called “fake” with a flashed controller), such cards can show full volume, but when writing data above a certain limit, old files begin to be overwritten, which leads to their corruption.
- 📉 Slow work – check if the card is full and try defragmenting it on your computer.
- 🔌 Reading errors - wipe the contacts of the card with a wipe or an alcohol napkin, check the density of the fit in the slot.
- 📂 Files are not copied – check the file system, possibly a file larger than 4GB, and the card is in format FAT32.
If the smartphone is cyclically rebooted with the card inserted, the file table may be damaged, in which case you will need full formatting via PC using the SD Formatter utility, which conducts deep cleaning and testing sectors.
💡
The most common cause of memory problems in Redmi 4X is file system incompatibility or physical wear of the card contacts, not the breakdown of the smartphone itself.