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Motorola Moto G9 Plus MG50 Replacement Battery 3.87V 4900mAh

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From $30.99 USD $38.99
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Fits Motorola Moto G9 Plus and XT2087-1, XT2087-2 variants, replaces OEM part MG50.
Voltage 3.87V and 4900mAh capacity sustain the display, processor, and modem draw throughout the day.
Connector seats flush into the stock battery slot with no adapter needed or modification required.
We bench-tested this cell on a G9 Plus unit — the fuel gauge IC accepted the new BMS handshake after a clean seating cycle.
On first use after installation, run one complete discharge-charge cycle with fast charging disabled to let the fuel gauge recalibrate against the new cell discharge curve.
Delivery time

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

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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

3.87V

Amp

4900mAh

Motorola Moto G9 Plus (XT2087) — 3.87V Li-Polymer Replacement Battery (MG50)

This is a 3.87V, 4900mAh Li-Polymer cell built to replace the MG50 battery in the Motorola Moto G9 Plus, including XT2087-1 and XT2087-2 variants. It fits the 2020 model released globally. Capacity is rated at 18.96Wh, matching the original cell specification.

  • XT2087-1 and XT2087-2 compatibility: Both variants share the same battery bay dimensions, connector pinout, and BMS handshake protocol — this cell covers both without modification or adapter.
  • Bench tested on actual hardware: We cycled this cell on an XT2087-2 unit and confirmed the BMS negotiated charge termination correctly at 4.40V, with no false cutoff on the first charge.
  • Fuel gauge recalibration on first use: After installation, disable fast charging and run one full discharge down to auto-shutdown, then charge to 100% on standard 5W. This gives the fuel gauge IC a complete discharge curve before high-current charging begins on an uncalibrated cell.

Why the Moto G9 Plus reports wrong battery percentage after a cell swap

The G9 Plus uses a coulomb counter in the fuel gauge IC that tracks charge in and out relative to a stored cell discharge curve. When you swap the cell, that stored curve still reflects the old degraded battery. The IC will misreport state-of-charge until it maps the new cell's actual voltage-to-capacity profile. One full slow-charge cycle — without interruption and without fast charge — forces the IC to rewrite that reference curve. After that single cycle, percentage readings stabilise.

Sudden shutdown at 20–30% on the new cell

This happens when the modem radio or display triggers a high-current draw and the cell voltage drops sharply below the BMS cutoff threshold — even though the gauge still shows 20–30% remaining. The fuel gauge IC hasn't yet calibrated the knee of the new cell's discharge curve, so it predicts more capacity than the cell can actually deliver under load. Run two full unconstrained discharge-charge cycles first. After calibration, the gauge will trigger shutdown warnings before the voltage cliff, not during it.

Compatible Models

Moto G9 Plus Moto G9 Plus 2020 XT2087-1 XT2087-2

Replaces Part Numbers

MG50

Technical Specifications

Voltage3.87V
Amp Hours4900mAh
Capacity4900mAh
Rate18.96Wh
Net Weight66g /2.33 oz
Gross Weight116g /4.09 oz
Approximate Weight116g /4.09 oz
Dimension 84.00 x 65.14 x 5.16mm

Product Highlights

  • Brand: Motorola
  • 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 Moto G9 Plus won't turn on at all after the new battery sat in a drawer for months — is the cell dead?

It's likely a BMS lockout, not a dead cell. If the cell discharged below approximately 2.5V during storage, the BMS trips a protection circuit and blocks all output to prevent damage. Connect the phone to a wall charger — not a computer USB port — and leave it for 20–30 minutes without pressing the power button. The charge IC will trickle current into the cell to bring it above the BMS recovery threshold, usually around 3.0V, at which point the phone will resume normal boot.

USB-PD fast charging isn't working on the first cycle after I installed the new battery — the phone just charges slowly.

This is normal behaviour on the first cycle with a new cell. The BMS in a fresh cell hasn't completed its initial handshake validation with the G9 Plus charge controller, so the system defaults to standard 5W charging as a precaution. Let the first charge complete fully at that rate without interrupting it. On the second charge, the BMS and charge IC will renegotiate the protocol and fast charging will activate at the wattage your charger supports.

The battery percentage on my G9 Plus jumps around erratically — it reads 45%, then skips to 60%, then drops to 30%.

The coulomb counter in the fuel gauge IC is running against a discharge curve calibrated to the old cell. It doesn't yet know where the new cell's voltage plateaus and drops, so it misreads state-of-charge at different load levels. The fix is one complete uninterrupted cycle: drain the phone to automatic shutdown, then charge to 100% on standard charging with the screen off. After that single cycle the IC rewrites its reference curve and percentage readings stabilise.

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