The battery is one of the most vulnerable components of Xiaomiβs smartphone, which eventually loses capacity and stops holding charge. If your phone quickly discharges, spontaneously turns off or requires frequent recharging, itβs time to check the status of the battery. The most reliable way to diagnose is to use a multimeter that allows you to measure voltage, current and even indirectly assess the residual capacity.
In this article, youβll find step-by-step instructions for checking Xiaomiβs battery (including Redmi models, POCO And Mi, with a multimeter, you can understand the standard values and interpret the results, and we can also tell you what mistakes users make and how to avoid them so that you don't damage your battery or your phone. If you've never worked with a multimeter, don't worry. The instruction is adapted for beginners, with photos and explanations of each step.
Why is a multimeter the best way to test your battery?
There are several ways to diagnose a smartphone battery: through Settings β Battery status, special applications (e.g. AccuBattery), or visual inspection for bloating, but all of these methods have limitations:
- π± Software tests (such as Mi Battery Doctor) show only approximate wear and do not display real voltage or current.
- π Visual inspection helps to identify only critical defects (blown, leaks), but does not give data on capacity.
- π Chargers with a display (for example, Baseus) show the current of charge, but do not allow to measure the voltage at the terminals of the battery.
The multimeter gives accurate data on voltage, resistance and current, which allows:
- β‘ Determine the actual battery voltage (including under load).
- π Identify voltage drawdowns that lead to sudden phone shutdowns.
- π Estimate the degree of wear by the difference between the nominal and actual voltage.
- π§ Check the integrity of the charging circuits (for example, if the phone is not charging).
In addition, the multimeter is inexpensive (from 300 rubles), and it can be used to diagnose other equipment - from powerbank to laptops, the main thing is to connect the probes and interpret the readings correctly.
What tools will you need to check?
To test the Xiaomi battery yourself, prepare the following set of tools:
| Tool. | Appointment | Where to Buy/Alternative |
|---|---|---|
| Multimeter | Measurement of voltage, current, resistance | AliExpress, Ozon, radio stores (from 300) β½) |
| Setting screwdrivers (T3, T4, T5) | Disassembly of the smartphone body | Any tool store or phone set |
| Plastic mediator or shoulder blade | Safe opening of the back cover | You can replace a guitar mediator or a bank card. |
| Strain or shrink tube | Contact isolation after inspection | Any hardware store |
| Alcohol napkins | Cleaning the battery contacts | Pharmacy or electronics store |
If you don't have a multimeter, you can rent it from tool rental services (for example, All Tools), or borrow it from friends. Even the most budget model will do for a one-time check, the main thing is that it can measure constant voltage (DC) up to 20 V.
β οΈ Warning: Do not use metal screwdrivers to open the case - they can damage latches or leave scratches. Plastic or silicone mediators are safer and cheaper (cost from 50 rubles).
Preparing a smartphone for testing: how to safely remove the battery
Before you test the battery with a multimeter, it must be removed from the phone. In most Xiaomi models (for example, Redmi Note 10 Pro, POCO X3 Pro, Mi 11) removable battery, but soldered to the board in a plume:
Turn off the phone and remove it. SIM-map|Remove the back cover with a plastic mediator|Unscrew the screws that fix the metal plate of the battery|Carefully disconnect the power plume from the motherboard|Donβt pull the wires β just take the connector.-->
Step-by-step process:
- Turn off your phone and wait for the device to shut down completely (the vibration or charge indicator should not work). If the battery is swelling, don't turn on the device - it's dangerous!
- Remove the back cover. Most Xiaomi models have it mounted on the latches. Put a plastic mediator in the gap between the lid and the body (better start at the bottom corner where the charging connector is) and carefully drive along the perimeter. If the lid does not lend itself, heat it slightly with a hairdryer (not higher than 60).Β°C).
- Unscrew the screws that hold the metal plate over the battery. T3 or T4. Put them in a separate box so you donβt lose them.
- Disconnect the battery plume. It's attached to the motherboard with a connector. Put a plastic blade or a nail on it (don't use metal!) If the plume is glued, gently apply the tape.
- Remove the battery. It can be glued to the body with double-sided tape. Put a plastic blade on the battery and slowly pull up. If the tape doesn't lend itself, heat it with a hair dryer (maximum 50).Β°C).
If youβve never taken your phones apart, check out the video manual for your model on YouTube (e.g., search for βXiaomi Redmi Note 9 Pro disassemblyβ) to help avoid errors and damage.
β οΈ Warning: If the battery is swelling (phone cover is up, battery is deformed), do not try to check or charge it. Li-ion batteries that are blazing can ignite! Dispose of it immediately at the hazardous waste point.
How to connect a multimeter to the Xiaomi battery?
Now that the battery is out, you can start measuring, and it's important to connect the multimeter probes correctly so that you don't damage the battery or the appliance.
Step 1: Set up the multimeter
- π΄ Connect a red probe into a nest with the inscription VΞ©mA (voltage-measuring).
- β« Put the black probe in the nest. COM (general).
- Turn the mode switch to 20V DC (constant voltage, range up to 20 volts).
Step 2: Determination of polarity
Xiaomiβs battery usually has a marking:
- + (plus) - red contact.
- - (minus) - black contact.
If there is no marking, look at the plume: the red wire usually corresponds to the plus, the black wire - the minus.
Step 3: Connect the probes
Apply the multimeter probes to the battery contacts:
- π΄ Red probe -- to +.
- β« Black probe to the β.
Hold the probes tightly, but without effort, so as not to damage the contacts.
Step 4: Withdrawal of testimony
The multimeter screen will show the current battery voltage, and write down the value, which will be needed for further analysis.
π‘
If the multimeter shows negative voltage, you've got the polarity mixed up. Just swap the probes around, it's not dangerous for the battery.
Xiaomi battery voltage: how to decipher the results?
The voltage values obtained should be compared with the standard ones. For lithium-ion and lithium-polymer batteries (which are used in Xiaomi), the following standards apply:
| Battery status | Voltage (V) | What does that mean? |
|---|---|---|
| 100% charge | 4.2 β 4.35 | The battery is fully charged. Normal for new batteries. |
| 50% | 3.7 β 3.8 | Medium charge level. Optimal voltage for storage. |
| 20% charge | 3.4 β 3.5 | The phone's going to shut down soon. |
| Critical discharge | 3.0 β 3.2 | The battery is deep. It requires urgent charging. |
| Damaged battery. | Below 2.8 | The battery is out of order. Charging may not help. |
If your battery voltage is above 4.35V, it suggests overcharging, which is dangerous for lithium-ion batteries (can lead to bloating).Voltage below 3.0V indicates a deep discharge - such batteries often do not recover even after charging.
An example of decryption:
- π± Does your Redmi 9 turn off at 30% charge? Measure voltage - if it's below 3.5V at this level, the battery is worn out.
- β‘ Phone charges to 100% but voltage doesn't rise above 4.0V.
- π Does the voltage sag from 4.2 V to 3.6 V in 10 minutes of play.
π‘
If the battery voltage at 100% charge is below 4.0 V, its capacity has dropped by at least 30%.
Checking the current leak: why does the phone discharge on its own?
If your Xiaomi is running out of power or loses 10-20 percent of its charge overnight, the problem may be a leakage current, a small current that the battery consumes even when the phone is not in use, and the normal leakage current for smartphones is up to 0.1 mA. If it is higher, there is a short circuit or a faulty component somewhere in the circuit.
How do you measure the leakage current?
- Transfer the multimeter to current measurement mode (200mA DC).
- Disconnect the battery plume from the motherboard.
- Connect the red probe to the + The battery, and the black probe, to + on the motherboard (where the plume is connected).
- Turn on the phone. The multimeter will show the current consumed by the device in standby mode.
Leakage current rates:
- π΅ 0.01 β 0.1 mA β the norm for switched off phone.
- π 5-20 mA β Standby mode (screen off, background processes).
- β οΈ 50 mA or higher - high current leakage. the cause may be a faulty module (for example, a modem) 4G display).
If the leakage current is higher than normal, try:
- π Get out. SIM-card and memory card β they can consume excess current.
- π οΈ Disable background applications through Settings β Battery β Optimization.
- π§ Reset to factory settings (if the software is a problem).
What to do if the current leakage is too high?
Frequent errors when checking the battery multimeter
Even experienced users sometimes make mistakes that can lead to inaccurate measurements or even battery damage, and the most common of these are:
- β Measurement of current without loading. If you connect the multimeter to current measurement mode (10A) It's going to short-circuit the battery, so always put a load on it first (like a light bulb) and then a multimeter.
- β Ignoring polarity. If you confuse it. + And -- the multimeter will show negative voltage, but it's not dangerous.
- β Load testing without refrigeration. If you measure the voltage while playing or charging, the battery heats up and the readings are inaccurate.
- β If the multimeter wires are bare or cracked, this can lead to a short circuit. Always check the integrity of the probes before working.
- β Measuring the capacity without a tester, a multimeter cannot directly measure the capacity in mAh. USB-tester or special charger with diagnostic function.
Another common mistake is to check the battery immediately after charging, and lithium-ion batteries have a relaxation effect, where after disconnecting from charging, the voltage may temporarily overstate. Wait 1-2 hours to get accurate data.
β οΈ Warning: Never touch both battery contacts simultaneously with metal objects (such as a screwdriver) this will cause a short circuit that can cause a fire!
When should you replace the Xiaomi battery?
If the following problems have been identified after checking the multimeter, it is time to change the battery:
- π Voltage at 100% charge below 3.9V β Capacity dropped by more than 40%.
- β‘ The phone turns off at 30-40% of the charge - the voltage sags below the critical level.
- π The battery is swelling or deformed β even if it is still working, it is dangerous.
- π₯ Battery warms without load (temperature above 40)Β°C on standby).
- π Battery life has been reduced by 2 times (for example, instead of 10 hours β 4-5).
The cost of replacing the battery in the service center Xiaomi ranges from 1,500 to 3,000 rubles (depending on the model). Self-replacement will cost less (the battery costs from 500 to 1,500 rubles), but requires soldering skills (if the plume is soldered) and accuracy.
How to choose a new battery?
- π Buy only original batteries or certified analogues (for example, from the ZMI or Baseus).
- π Check the compatibility of the phone model (for example, BM47 For the Redmi Note 9 Pro).
- π Pay attention to the capacity - it should match the original (for example, 5020 mAh for the first time). POCO X3 NFC).
- π‘οΈ Check for overcharging and short circuit protection (marking) PCB battery-powered).
π‘
If you decide to replace the battery yourself, be sure to use a new double-sided tape for fixation.The old tape loses its stickiness and won't hold the battery when it falls.