The Mi Power Bank’s 10,400mAh external batteries have become legendary for their metal body and reliability. However, over time, even the highest quality lithium-ion cells lose their capacity and the power controller can fail. Disassembling the device is the only way to replace a worn battery or restore contacts that have oxidized after moisture.
Before you start dismantling, it’s important to understand that you’re dealing with an energy source that, if mishandled, can be dangerous. Unlike plastic counterparts, Xiaomi’s aluminum case hides a complex mounting system that requires precision and special tools. Inside the case, there are two standard 18650 cells that can be replaced with new batteries of the same capacity.
This article will be a detailed guide for those who want to extend the life of their gadget or save money on buying a new device.We will look not only at the autopsy process, but also at the nuances of working with electronics, as well as the possible risks that you may face in the process.
Essential tools and precautions
For a high-quality and safe disassembly, you will need a minimal but specific set of tools. Using improvised tools such as knives or screwdrivers from a screw kit can damage the body or, worse, short circuit, the main tool will be a dryer to heat the adhesive base and a thin plastic card to bend the plugs.
Safety should be the first priority, as we work with lithium cells, any damage to the battery shell can lead to fire or chemical burns, before starting work, make sure that the device is completely discharged or, conversely, not more than 30-40% charged to minimize the power in the circuit.
⚠️ Warning: Never use metal objects (needles, scalpels) to put plugs near the scalpel. USB-ports, as there is a high risk of damage to the internal controller fee.
Prepare the workplace: it should be well lit and have no conductive surfaces; a wooden table or a special antistatic mat is ideal; dielectric gloves are also recommended if you have a tendency to static electricity, which can damage sensitive microelectronics.
- 🔧 Plastic blade or mediator for opening the body.
- 🔥 Hair dryer construction or household for heating end plugs.
- 🔋 New 18650 batteries (if replacement is planned).
- 🧤 Dielectric gloves and protective glasses.
☑️ Preparation for disassembly
Anatomy of the device and design features
The Xiaomi Mi Power Bank 10400 is made in an all-metal body, which gives it a premium look, but significantly complicates access to the insides. Structurally, the device is a tube, closed on both sides with plastic plugs, these plugs hold all the stuffing inside and seal the battery assembly.
Inside is a charge-discharge controller control board, which has two power cells connected in series, and it's mounted on a plastic frame, which is then inserted into an aluminum pencil, and all of the connections are done by spot welding or soldering, which requires careful extraction.
One of the key features is the thermal insulation system, which often includes a thin layer of insulating material between the elements and the walls of the housing, which prevents the aluminum shell from overheating, and it is important not to damage this layer when disassembling, so that the heat sink is retained during further use.
Why is the case metal?
Understanding the internal architecture will help you act with confidence. USB-The ports, the charge indicators and the activation button to avoid force in the wrong place.
End cap removal process
The most difficult part is removing plastic lids that are planted on a powerful industrial glue, and simply pulling them with your hands will not work, and using force will break the plastic, and first you need to carefully warm the ends of the device with a hairdryer.
Turn the dryer on to the average temperature and evenly warm one of the plugs for 2-3 minutes. Do not keep the hot air flow at one point for too long so as not to melt the plastic or damage the elements under it. Periodically check the heating by touching the surface with your finger (caution may be hot).
⚠️ Warning: Overheating the case above 80 degrees Celsius can cause lithium batteries to swell inside, so monitor the heating temperature carefully.
Once you warm up, take a thin plastic card or a mediator. Put it in the gap between the aluminum case and the plastic cap. Move the tool around the perimeter, gradually cutting off the softened adhesive layer. Act slowly, trying not to scratch the aluminum.
- 🌡️ Warm up the end of the device evenly for 120 seconds.
- 🃏 Insert a plastic tool in the gap between the metal and plastic.
- 🔄 Swipe the tool around, separating the plug from the body.
- 👐 Carefully pull the plug if it has started to move away.
Repeat the procedure on the other side of the device, and if the plug is very tight, you can add a little more heat, and the main thing is to take your time, because the rush at this stage often ends in cracked plastic, which then will be difficult to collect back.
Removal of internal boards and batteries
After removing both plugs, you will see the internal filling, usually on one side (where you are). USB-You can get the board tighter, you can gently tuck the plastic frame with the batteries, and you can slowly pull it out of the aluminum shell.
Inside, you'll see two cylindrical elements connected to each other and to the board, which can be further fixed by shrinkage or tape, and your task is to extract the assembly without damaging the wires going to the power controller.
If you're planning to just clean the contacts or check the connections, you may not need to disassemble them further, but you'll need to carefully unplug the nickel plates or re-sweat the contacts to replace the batteries.
When you extract, pay attention to the insulation state, if you see scuffs or damage on the wires, they must be immediately isolated, and using a device with damaged insulation can lead to a short circuit inside the metal housing.
Diagnosis and replacement of food items
The main reason for the loss of capacity is the degradation of chemical processes inside 18650 batteries. To diagnose, you will need a multimeter. Measure the voltage on each cell: if it is below 2.5-3.0 V, the cell is considered deeply discharged and requires replacement or complex resuscitation.
Replacement is made with similarly sized cells. It is important to choose batteries with current output corresponding to the characteristics of the original (usually at least 5-10 A). The use of cheap analogues can lead to overheating and rapid failure of the new power bank.
When installing new cells, you must observe polarity. The mixed plus and minus is guaranteed to disable the controller instantly. After installing new cells, it is recommended to conduct a training cycle: full charge and full discharge.
| Parameter | Original | Permissible analogue | Critical significance |
|---|---|---|---|
| Type of element | Li-Ion 18650 | Li-Ion 18650 | Li-Po (requires further development) |
| Nominal voltage | 3.7 V V | 3.6. to 3.7 B | Below 2.5 V |
| Capacity | 2600mAh (x2) | 2500 - 3000 mAh | Less than 2,000 mAh |
| Current output | Tall. | High (Power) | Low (normal) |
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When buying new batteries, pay attention to the date of production - lithium cells age even when stored, take the freshest ones.
Remember that the total capacity of the system consists of the capacity of both elements in series connection, but the voltage is added. Xiaomi controller is designed to work with a pair of elements, so you need to change both at once to avoid imbalance.
Assembly and performance check
The assembly is done in reverse order. Make sure all contacts are securely connected and the wires are not clamped by the body. Put the assembly back in the aluminum sleeve to check for ease of travel. Nothing should get stuck or creak.
Use a new double-sided tape or a special glue for electronics (e.g. B-7000) to fix the plugs, apply the glue in a thin layer so that the glue does not squeeze out and spoil the appearance. Press the plugs and let the glue dry according to the instructions.
Once assembled, connect the device to the charger. Indicators should light up to show the charge process. If the indicators flash randomly or do not light up at all, check the correct connection and integrity of the welds.
⚠️ Warning: The first charge after battery replacement may last longer than usual – this is normal, the controller needs time to calibrate the new capacity.
The performance check also includes a load test, plug a smartphone or other gadget into a power can and make sure that the charging is stable, without jerking or shutting down. If everything is working correctly, the assembly can be considered a success.
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The quality assembly and use of original or certified components ensure the safe operation of the remanufactured device.