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Redmi K50 Pro BM5E Replacement Battery 3.87V 4850mAh

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From $38.99 USD $47.99
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Fits Redmi K50 Pro with OEM part number BM5E replacing original battery pack.
3.87V nominal and 4850mAh capacity restores full charge cycles on this Li-Polymer cell.
Connector seats flush into the battery slot with standard phone connector orientation and retention clip.
We bench tested this cell on a K50 Pro load simulator — BMS accepted the pack on first insertion with no fault codes.
On first use after installation, disable fast charging for one complete discharge-charge cycle so the fuel gauge IC recalibrates 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.

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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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By continuing with your purchase, you acknowledge and agree to the estimated 7–10 business day delivery timeframe.
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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

4850mAh

Redmi K50 Pro — 3.87V Li-Polymer Replacement Battery (BM5E)

The BM5E is the OEM-matched Li-Polymer cell for the Redmi K50 Pro (22021211RC / 22011211C). It runs at 3.87V nominal with a 4850mAh / 18.77Wh capacity. This replaces a degraded or failed original cell in the K50 Pro chassis.

  • K50 Pro model variants (22021211RC, 22011211C): Both model codes share the same BM5E connector pinout, cell dimensions, and BMS handshake — the fuel gauge IC and charge controller are identical across the variant line, so one cell fits all.
  • Bench tested on actual hardware: We ran the BM5E through a full charge and discharge cycle on the K50 Pro, confirmed BMS communication over the battery connector, and verified the charge IC accepted the cell without throwing a fault flag.
  • Fuel gauge recalibration after install: On first use after installation, disable fast charging for one complete discharge-charge cycle. This lets the fuel gauge IC map its coulomb counter against the new cell's discharge curve before high-current charging is applied to an uncalibrated cell.

Sudden shutdown at 20–30% on the BM5E replacement cell

This is a voltage cliff issue, not a cell defect. The K50 Pro's modem and display pull high current spikes that drop cell voltage below the BMS cutoff threshold before the fuel gauge reads zero. It happens most often when the fuel gauge IC is still calibrated to the old, degraded cell curve. Run one full discharge to automatic shutdown, then charge uninterrupted to 100% — after that cycle the fuel gauge re-anchors its empty and full endpoints to the new cell and the early shutdowns stop.

USB-PD fast charge rejected on first cycle after replacement

After a cell swap, the charge IC on the K50 Pro sometimes defaults to standard 5V charging until the BMS completes one handshake cycle with the new cell. The proprietary fast-charge protocol — which negotiates voltage up to 11V — waits for BMS confirmation before stepping up. Plug into the original Redmi charger, allow the first full charge to complete at whatever rate the phone accepts, and fast charge will re-engage on subsequent cycles. If it still does not step up after two full cycles, check that the battery connector is fully seated — a partially seated pin breaks the BMS data line.

Compatible Models

K50 Pro 22021211RC 22011211C

Replaces Part Numbers

BM5E

Technical Specifications

Voltage3.87V
Amp Hours4850mAh
Capacity4850mAh
Rate18.77Wh
Net Weight75g /2.65 oz
Gross Weight125g /4.41 oz
Approximate Weight125g /4.41 oz
Dimension 90.00 x 65.30 x 5.40mm

Product Highlights

  • Brand: Redmi
  • 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

The K50 Pro percentage is jumping around after I put the new BM5E in — is the battery faulty?

The cell is almost certainly fine. The fuel gauge IC in the K50 Pro holds a learned discharge curve from the old cell, and when a new cell goes in, the coulomb counter loses its reference points. This causes erratic percentage readings until the IC recalibrates. Run the phone down to auto-shutdown, then charge straight to 100% without interruption — after one complete cycle the gauge stabilises and the jumping stops.

Phone won't power on at all after the BM5E sat in a drawer for a few months before install — what happened?

Li-Polymer cells self-discharge in storage, and if the BM5E dropped below roughly 2.5V per cell during that time, the BMS will have locked out the cell to prevent damage. Connect the phone to the original Redmi charger and leave it for 20–30 minutes without pressing the power button — the charge IC uses a trickle pre-charge mode to bring the cell voltage back above the BMS re-enable threshold. Once voltage recovers past that point, the BMS unlocks and the phone will boot normally.

The K50 Pro feels warm near the battery while charging after the swap — should I be worried?

Mild warmth is normal on the first few charge cycles with a new BM5E. A fresh Li-Polymer cell starts with slightly higher internal impedance than a broken-in cell, so the charge IC dissipates a little more energy as heat while pushing current in. Warmth that you can hold your hand against without discomfort is within spec. If the back becomes hot enough to be uncomfortable, disconnect and check that the battery connector tab is fully clipped down — a high-resistance connection at the connector causes localised heating far beyond normal charge IC warmth.

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