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BLP841 Oppo Realme 8 Replacement Battery 3.85V 4850mAh

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From $30.99 USD $38.99
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Fits Realme 8, Realme Q3, Realme Q3I, and RMX3085 models; replaces OEM part number BLP841.
Voltage runs 3.85V nominal; 4850mAh capacity matches the original cell's charge capacity for normal daily use cycles.
Connector is soldered to motherboard with standard smartphone contact pads; physical fit confirmed against OEM battery housing slot.
Bench testing showed the BMS accepted a full charge cycle with no cutoff faults; voltage held steady under load simulation.
On first use after installation, disable fast charging for one complete discharge-charge cycle — this lets the fuel gauge IC recalibrate against the new cell discharge curve before USB-PD pushes current into an uncalibrated cell.
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.

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⚠️ 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

4850mAh

Oppo Realme 8 / Realme Q3 Series — 3.85V Li-Polymer Replacement Battery (BLP841)

This is a 3.85V, 4850mAh (18.67Wh) Li-Polymer replacement battery for the Oppo Realme 8, Realme Q3, Realme Q3I, and RMX3085. It fits directly where the OEM BLP841 cell sits. Swap it when the original cell no longer holds charge, swells, or causes unexpected shutdowns.

  • Realme 8 and Q3 platform compatibility: The Realme 8, Q3, and Q3I share the same battery bay geometry, connector pinout, and BMS communication protocol — all three accept the BLP841 cell without modification to the charge circuit or connector housing.
  • Bench tested on actual hardware: We ran this cell through full charge-discharge cycles on Realme 8 hardware. The BMS handshake completed correctly, charge current stepped down at the expected cutoff threshold, and the fuel gauge IC accepted the cell without throwing a battery health warning in settings.
  • First-cycle fuel gauge reset on the Realme 8: On first use after installation, disable fast charging and run one complete discharge-charge cycle on standard 10W charging. This lets the fuel gauge IC map the new cell's discharge curve before high-current fast charging pushes significant current into an uncalibrated cell.

Sudden shutdown at 20–30% on the Realme 8 after a cell swap

A fresh cell with a factory-set discharge curve will not match the coulomb counter data stored from the degraded original. The fuel gauge IC reads percentage against an old reference table, so it reports 25% when the cell voltage has already dropped below what the processor and modem can sustain under load. The result is an abrupt shutdown — not a drained battery. One full discharge to 3.2V and a complete charge to 4.35V recalibrates the counter against the actual new cell curve.

VOOC or fast charge not activating on the first charge cycle after replacement

Oppo's proprietary fast charge protocol includes a handshake between the charger, the phone's charge IC, and the battery BMS. On a first cycle with a new cell, the charge IC defaults to standard 5V/2A input until it confirms BMS parameters are within spec. This is normal protective behaviour, not a fault with the battery or charger. Complete one full standard charge cycle first — fast charging typically activates automatically from the second cycle onward once the BMS has confirmed cell impedance is within the expected range.

Compatible Models

Realme 8 Realme Q3 Realme Q3I RMX3085

Replaces Part Numbers

BLP841

Technical Specifications

Voltage3.85V
Amp Hours4850mAh
Capacity4850mAh
Rate18.67Wh
Net Weight66.2g /2.34 oz
Gross Weight116.2g /4.10 oz
Approximate Weight116.2g /4.10 oz
Dimension 89.90 x 62.60 x 4.60mm

Product Highlights

  • Brand: Oppo
  • 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 Realme 8 powers on but shuts off the moment I open the camera or start a call — battery shows 40% right before it dies. What's happening?

The camera and modem are the two highest instantaneous current draws on this phone. If the new cell's fuel gauge IC hasn't been recalibrated yet, the percentage shown is based on the old degraded cell's discharge map — 40% on screen can mean the actual cell voltage is already near collapse under load. Run one full discharge to the point the phone powers itself off, then charge uninterrupted to 100% on standard charging, not fast charge. After that cycle the coulomb counter will track the new cell correctly and the shutdowns should stop.

My Realme 8 won't turn on at all after the replacement battery sat in a drawer for a few months before I installed it — the screen stays black even on charge. How do I recover it?

Li-Polymer cells self-discharge in storage, and if the cell dropped below approximately 2.5V the BMS will have tripped into lockout mode to prevent cell damage — it blocks all current flow, including from the charger. Plug into a 5V/1A charger (not a fast charger) and leave it connected for 20–40 minutes without pressing the power button. The charge IC on the phone will trickle current into the cell below the BMS lockout threshold; once cell voltage climbs back above 2.7V the BMS resets and normal charging resumes.

The battery percentage on my Realme 8 jumps around — it reads 67%, then drops to 51% without me doing anything, then climbs back up. Is the battery faulty?

This is the fuel gauge IC recalibrating. The IC uses a stored model of the cell's voltage-to-capacity curve to estimate percentage — when a new cell goes in, that model no longer matches the physical cell, so the reported number drifts erratically as the IC corrects itself in real time. It is not a sign of a faulty cell. The fix is one complete uninterrupted discharge (use the phone normally until it shuts off automatically) followed by a full charge to 100% without unplugging early — after that cycle the IC locks onto the correct curve and percentage readings stabilise.

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