How to fix the battery of the Xiaomi electric scooter: a complete guide with photos and schemes

Xiaomi scooters are some of the most popular vehicles in the city, but their weak point is often the battery. Over time, the battery loses capacity, the scooter travels less than a kilometer on a single charge, and in the worst cases, it stops turning on altogether. Don't rush to buy a new battery or scooter! In 80% of cases, the battery can be restored on its own, saving up to 15,000 rubles.

In this article, we will analyze all possible malfunctions of Xiaomi batteries. M365, Pro 2, 1S, Essential and other models, we'll diagnose the problem and fix it at the lowest cost, and you'll learn how to cut cans, calibrate them. BMS, Reestablish contacts and even resuscitate a dead battery that doesn't show signs of life, all of which are backed up with real cases, diagrams and photos from the disassembly.

⚠️ Important: Lithium-ion batteries require caution. If mishandled, there is a risk of fire or explosion. If you are not sure of your skills, consult a specialist. In this article, safety measures are outlined, but you are responsible for the actions.

1. Signs of Xiaomi battery failure: how to recognize the problem

The first step is to diagnose correctly, and many users confuse battery failure with controller or motor problems, wasting time on unnecessary repairs, and here are the key symptoms that point to the battery:

• 🔋 The scooter discharges quickly (it travels less than 10 km on a full charge, although it used to ride 20 km).+ km).
• ⚡ The charge indicator jumps (shown 100%, then drops sharply to 20%).
• 🛑 The scooter does not turn on, although the charger shows a green indicator (full charge).
• 🔥 The battery heats up when charging or driving (temperature above 50)°C).
• 💥 Bloated banks are visible (battery block is deformed).

If one of these signs shows up, the battery is the problem, but before repair, you have to rule out other malfunctions. M365 The Pro may not be driving because of a burnt-out controller or a cliff in the wiring. To make sure that the battery is to blame, do a simple check:

1. Connect the charger to the scooter and measure the voltage at the output of the power supply (should be 42V ± 0.5V).
2. Turn off charging and measure the voltage on the contacts of the battery (normal: 36V–42V).
3. If the voltage on the charge is, but on the battery is not - the problem is BMS-cliff-board.

2. Disassembly of the battery unit: step-by-step instructions with photo

To get to the insides of the battery, you have to take it apart carefully. Xiaomi uses sealed cases with latches and glue, so you have to be careful.

• 🔧 Plastic mediator or guitar mediator (so as not to scratch the body).
• 🔨 Cross screwdriver (usually) PH2).
• 🧲 Fryer (for softening glue).
• 📸 Phone for photographing the location of wires (useful when assembling!).

Disassembly order:

1. Unscrew the 4 screws on the bottom battery cover (they can be hidden under stickers).
2. Warm up the hair dryer seam around the perimeter of the body (temperature) ~60°C, don't overheat!).
3. Carefully put the mediator on the lid, starting at the corner. If it's tight, warm up again.
4. Unplug the connector. BMS-battery pack charge (do not pull the wires!).

Inside you'll see:

• 🔋 Battery unit (10-15 lithium-ion cells 18650 or 21700, connected in series-parallel).
• 📱 BMS-charge (charge/discharge management system).
• 🔌 Power connector (to connect to the scooter controller).

⚠️ Warning: If you see bloated cans, they can't be rebuilt, because they can explode when charged, and the only way out is to replace all the cans in the block.

Diagnostics of the battery: checking voltage and resistance

After disassembly, you need to diagnose each can in the block (DC 20V) resistance (200Ω).

Step 1. Check the voltage on the banks

Xiaomi's battery pack consists of 10 to 15 cells connected in series. Normal voltage on one can: 3.6V–4.2V. If at least one bank shows:

• 0V–2.5V → Deep discharge (you can try to restore it).
• 2.5V–3.0V → partial discharge (balancing is required).
• higher 4.3V → Recharge (dangerously, requiring replacement).

Step 2: Checking internal resistance

The high resistance of the bank indicates its degradation.

1. Put the multimeter in mode 200Ω.
2. Connect the probes to the bank contacts.
3. Normal resistance: 20-80 mOhm. If above 100 mOhm, the jar is worn out.

Step 3. Checking. BMS-pay-off

BMS (Battery Management System controls charge and discharge. If it burns, the scooter won't turn on, even if the banks are in good shape. BMS:

• 🔌 No voltage at the output connector with the battery connected.
• 💡 The charge indicator does not burn or flashes chaotically.
• 🔥 The plate is blackened or smells of a burn.

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If you do not have a multimeter, you can use it. USB-Tester (e.g. Xiaomi) ZMI). It will show voltage and current charge, which will help to identify problems with the BMS.

4. Battery recovery: calibration and balancing of cans

If the banks are unbalanced (one shows) 4.2V, other — 3.8V), The battery will run out quickly. Calibration helps to level the voltage and return the capacity:

Method 1: Calibration through BMS (programmatic)

Some Xiaomi models (such as the Pro 2) support calibration through the official Mi Home app:

1. Connect the scooter to the app.
2. Go to Settings. → Calibration of the battery.
3. Follow the instructions on the screen (usually you need to completely discharge and then charge the scooter).

Method 2: Manual balancing (for advanced)

If the software calibration does not help, you will have to balance the banks manually:

1. Disassemble the battery and disconnect BMS-fee.
2. Connect a balancing charger (e.g. iMax) B6) bank-to-bank.
3. Charge all the banks up to 4.2V currenty 0.5A.
4. Discharge the block to 3.0V under load (you can use a light bulb on the 12V).
5. Repeat the cycle 2-3 times.

⚠️ Warning: Don't balance the banks separately from the block! this can lead to reverse polarity and short circuit.Always work with a fully assembled battery (except when the cells are replaced).

5. Replacement of faulty cans: choice of cells and soldering

If one or more of the jars fail (swelled, do not hold the charge), they should be replaced.

• 🔋 Capacity: 2500-3500 mAh (original in M365 — 2900 mAh).
• 🔌 Maximum discharge current: 10A–20A.
• 📌 Type: Li-ion (not LiPo!).

Recommended models for replacement:

• 🔋 Samsung 30Q (3,000 mAh, 15A) — Best option in terms of price/quality.
• 🔋 LG HG2 (3,000 mAh, 20A) — speed-lovers.
• 🔋 Panasonic NCR18650B (3400mAh, 6.8A) — power-up.

Step-by-step replacement:

1. Seal off a faulty jar, having previously discharged it before 0V (safe).
2. Install a new jar while observing polarity.
3. Soak it with a pinpoint welding or a powerful soldering iron (at least) 60W). Don't overheat!
4. Check the voltage on the new bank – it should match the neighboring ones (±0.1V).
5. Collect the block, isolate the contacts with captone tape.

⚠️ Note: When soldering, use flux for aluminum (Xiaomi banks often have aluminum contacts!

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Replacing the cans with more capacious ones (for example, from 2500 mAh to 3,500 mAh) will increase the range by 20-30%, but can reduce the service life due to increased load on the car. BMS.

6. Repairs. BMS-Replacement: Replacement and Replacement of Elements

If the battery is not charged or does not give current, the problem may be in the BMS-Frequent malfunctions:

• 🔥 Mosfet transistors (responsible for discharge) burned).
• 💻 Flew the firmware (scooter does not determine the battery).
• 🔌 Contacts are oxidized (poor contact with banks).

How to repair BMS:

Method 1: Flashing over

For Xiaomi. M365/Pro can be re-examined BMS via ST-Link (programmer) and program STM32CubeProgrammer:

1. Connect ST-Link to the SWD contacts on the board.


2. count the current firmware (team: Read).




3. Download the solid firmware dump (can be found on forums, for example, 4PDA).




4. Write it down to the microcontroller (Write).




5. Turn off the power, then check the work.

Method 2: Replace mosfets

If the transistors are burned, they can be replaced by the following:

• 🔧 For M365 fit AO4407 or IRLB8743.
• 🔧 For the Pro 2 — SI4410DY.

When soldering, use a thermal air station with a temperature not higher than 300°C, so as not to peel the tracks off.

Where to buy spare parts for BMS:

• 🛒 AliExpress (search by chip number).
• 🛒 Local radio market shops.
• 🛒 Groups in Telegram for the repair of electric scooters.

7. Extension of battery life: operating tips

Even after repair, the battery will last longer if you follow the following simple rules:

• 🔋 Don’t discharge below 20% – a deep discharge kills lithium-ion cans.
• ⚡ Charge at 10-30 temperatures°C - in the cold, the capacity falls, and in the heat, the battery degrades faster.
• 🛑 Store with a charge of 40-60% – if you do not use a scooter in the winter, do not leave it 100% or 0%.
• 🔄 Once every 3 months, do a full discharge-charge cycle for calibration. BMS.
• 🚫 Don’t use unoriginal chargers – they can recharge banks.

Optimal Storage Conditions for Li-ion Batteries

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If you keep a scooter in the winter, turn it on once a month for 10-15 minutes and drive a small circle, which will prevent the cans from falling asleep and prolong life. BMS.

8 Frequent repair errors and how to avoid them

Many beginners make critical mistakes that lead to a battery failure, and here are the most common:

• 🔥 Rideless. BMS → short-circuit.
• 💥 Using cans of different capacity → imbalance and failure.
• 🔌 Connecting charging to the disassembled battery → burnt BMS.
• 📉 Ignoring bloated cans → charge-explosion.
• 🔧 Flush-free rations → cold contacts and tension drawdowns.

How to avoid problems:

1. Always turn it off. BMS before ration.
2. Use banks of the same model and batch.
3. Check the polarity with a double multimeter (one per can, the other per block).
4. After assembly, check the insulation with a megaohmmeter (resistance between banks and the case should be >1 MOOM).

⚠️ If the scooter does not travel beyond 500 meters after repair, most likely you have soldered the cans incorrectly or did not calibrate. BMS. In this case, you can not operate a scooter - this can lead to fire!

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The most common reason for a battery to fail after repair is to balance the cans incorrectly. Always check the voltage on each cell after assembly!

FAQ: Answers to Frequent Questions