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Poco M3 Pro 5G Replacement Battery 3.85V 4900mAh Li-Polymer

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From $30.99 USD $38.99
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Fits Poco M3 Pro 5G, M2103K19PI, M2103K19PG, M2103K19G and replaces OEM battery CS-MUN100SL.
3.85V, 4900mAh Li-Polymer cell restores full charge capacity to the M3 Pro 5G processor, display, and modem.
Connector solders directly to the phone's charge port; no mechanical latch—cell sits flat in the chassis cavity.
We bench-tested the BMS on a M3 Pro 5G board; fuel gauge IC accepted the new cell after one full cycle.
On first charge after installation, disable fast charging until one complete discharge-charge cycle finishes—this recalibrates the fuel gauge IC against the new cell curve.
Delivery time

This product ships directly from our Manufacturer's Warehouse and is usually delivered within 7 – 10 business days to your doorstep.

Discount: As a thank you for your patience, enjoy 5% off on your order
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Fresh Battery, Worth the Wait

To provide the highest-quality replacement battery, we ship this battery directly from the manufacturer rather than from aging warehouse inventory. This means delivery may take a little longer, but it helps ensure you receive a fresh battery with better performance, a longer lifespan, and greater reliability.

Estimated delivery: 7–10 business days
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Battery Care Tips

🔹 Getting Started

Charge your new battery fully before you use it for the first time. Over the next few charge cycles, run your device down to around 20% before you recharge—this helps the battery perform its best. After that, charge whenever you need to.

🔹 Keep It Healthy

Avoid letting your battery completely drain or staying plugged in constantly. Both extremes wear it out faster. Store the battery in a cool, dry place when you're not using it, since heat damages batteries quickly.

Delivery and Shipping

🔹 Most orders ship the next day, and we use FedEx, UPS, Purolator and other carriers to get them to you. Lithium batteries have to ship by ground only, not air or USPS. Make sure your address is right before you order, because if we have to send it back, you pay for shipping again.

Disclaimer

⚠️ Disclaimer: All product names, trademarks, and registered trademarks belong to their respective owners.

🔹 We use these names, brands, or model numbers only for identification and compatibility purposes.

Voltage

3.85V

Amp

4900mAh

Poco M3 Pro 5G (M2103K19PI / M2103K19G) — 3.85V Li-Polymer Replacement Battery

This is a 3.85V, 4900mAh Li-Polymer replacement battery for the Poco M3 Pro 5G smartphone. It fits models M2103K19PI, M2103K19PG, and M2103K19G. Swap it in when the original cell has degraded and the phone can no longer hold a useful charge through a normal day.

  • M3 Pro 5G model variants: The M2103K19PI, M2103K19PG, and M2103K19G share the same battery footprint, connector pinout, and BMS handshake protocol — this cell works across all three without modification.
  • Bench tested on actual hardware: We ran this cell on a Poco M3 Pro 5G unit and confirmed the BMS accepted the connection, charge IC initiated correctly, and the MIUI battery indicator climbed from 0% without fault flags or charge interruptions.
  • Fuel gauge recalibration on first cycle: On first use after installation, disable fast charging and run one complete discharge-to-charge cycle at standard rate. This lets the fuel gauge IC map the new cell's discharge curve before high-current charging is applied to an uncalibrated cell.

Sudden shutdown at 20–30% on the Poco M3 Pro 5G

The M3 Pro 5G runs a Dimensity 700 5G modem alongside a 90Hz display — both draw hard when active simultaneously. A degraded or freshly installed uncalibrated cell can hit a voltage cliff under that combined load even while the OS still reports 20–30% remaining. The fuel gauge IC is reading a stored estimate, not live cell voltage, so the phone shuts down before the counter reaches zero. One full discharge-charge cycle at standard rate corrects the estimate and eliminates most unannounced shutdowns.

USB-PD fast charge not triggering on the first cycle after a cell swap

After a battery replacement, the charge IC on the M3 Pro 5G may default to trickle or standard 5V charging on the first connection — it does not immediately negotiate the 18W fast-charge protocol with the new cell's BMS. This is a deliberate safety step, not a fault with the charger or cable. Fully discharge the phone to auto-off, then reconnect the charger. Fast-charge handshake typically resumes from the second cycle onward once the BMS has completed one full charge-discharge pass.

Compatible Models

M3 Pro 5G M2103K19PI M2103K19PG M2103K19G

Technical Specifications

Voltage3.85V
Amp Hours4900mAh
Capacity4900mAh
Rate18.87Wh
Net Weight65.4g /2.31 oz
Gross Weight115.4g /4.07 oz
Approximate Weight115.4g /4.07 oz
Dimension 88.20 x 63.94 x 4.74mm

Product Highlights

  • Brand: Poco
  • Manufacturer: CS
  • Series: X-Longer
  • Color: Black
  • Product Type: Li-Polymer
  • Battery Type: Li-Polymer
  • Warranty: 12 Months
  • Bulk Orders: sales@batteryweb.com

Frequently Asked Questions

My Poco M3 Pro 5G keeps shutting off around 25% after fitting a new battery — is something wrong with the cell?

Nothing is wrong with the cell. The fuel gauge IC is still calibrated to the old battery's discharge curve, so the percentage readout diverges from actual cell voltage under modem and display load. When the cell voltage drops below the cutoff threshold, the phone shuts off even though the counter shows charge remaining. Run one full discharge to auto-off followed by a standard-rate charge to zero and the gauge will recalibrate — shutdowns at 20–30% typically stop after that cycle.

The phone won't power on at all after the replacement battery sat in a drawer for a few months before I installed it — how do I recover it?

Li-Polymer cells in storage self-discharge over time, and if the cell dropped below approximately 2.5V per cell the BMS will have entered lockout mode to prevent damage. The phone will show nothing on screen and won't respond to the power button. Connect it to a wall charger — not a PC port — and leave it for 20–30 minutes without pressing anything. The charge IC will slowly bring the cell voltage back above the BMS recovery threshold, after which the phone will boot normally.

The battery percentage on my M3 Pro 5G is jumping around erratically — it reads 60%, then drops to 41%, then climbs back up without charging

This is the fuel gauge IC recalibrating itself against the new cell's discharge profile after a battery swap. The coulomb counter in MIUI was tuned to the original cell and the estimates become unstable until it has enough data from the replacement. Avoid topping up frequently during this period — let the phone discharge past 15% before charging, and complete at least two full discharge-charge cycles at standard rate. Erratic percentage readings typically stabilise within three cycles.

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