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BLP661 Oppo A3 Replacement Battery 3.85V 3300mAh

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From $25.99 USD $31.99
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Fits Oppo A3 and A3 Dual SIM models; replaces OEM battery BLP661.
3.85V, 3300mAh Li-Polymer cell restores full charge capacity for daily calling, messaging, and app use.
Connector seats flush into the A3's internal slot with no adapter needed; locking tab secures downward.
Bench testing showed clean BMS handshake on first cycle; no voltage sag under modem load at 80% state of charge.
On first use after installation, disable fast charging for one complete discharge-charge cycle to let the fuel gauge IC 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

3.85V

Amp

3300mAh

Oppo A3 / CPH1837 — 3.85V Li-Polymer Replacement Battery (BLP661)

The BLP661 is a 3.85V, 3300mAh Li-Polymer cell for the Oppo A3 and A3 Dual SIM smartphones, including the TD-LTE and CPH1837 variants. It restores power delivery to the phone's display, modem, and processor when the original cell has degraded or failed. Capacity and voltage match the OEM specification exactly.

  • A3 and CPH1837 series fit: All listed A3 variants share the same BLP661 connector pinout, cell dimensions (81.52 × 64.62 × 3.65mm), and 3.85V nominal voltage rail. The charge IC and BMS handshake are consistent across the Dual SIM and TD-LTE builds, so one cell covers the full model range.
  • Bench tested on actual hardware: We cycled the BLP661 through a full charge-discharge sequence on the CPH1837 board. The BMS accepted charge current at both standard and fast-charge rates, and the fuel gauge IC tracked cell voltage without error flags after the first complete cycle.
  • First-cycle fuel gauge reset: On first use after installation, disable fast charging and run one full discharge-to-charge cycle. The fuel gauge IC recalibrates its coulomb counter against the new cell's discharge curve — skipping this step leaves the IC mapping to the old cell's profile, which causes percentage errors early on.

Sudden shutdown at 20–30% on the Oppo A3 after a cell swap

The Oppo A3 shuts down abruptly at 20–30% because the fuel gauge IC is still running the degraded discharge curve from the old cell. When modem or screen load spikes, the new cell's actual terminal voltage drops below the shutdown threshold before the displayed percentage reaches zero. The IC interprets this as an immediate undervoltage event and cuts power. One full discharge cycle — draining to automatic shutdown, then charging uninterrupted to 100% — forces the coulomb counter to re-map to the new cell, and the false cutoffs stop.

Oppo A3 not powering on after the replacement battery sat in storage

Li-Polymer cells self-discharge in storage, and if the BLP661 cell dropped below approximately 2.5V, the BMS enters lockout to prevent damage from deep discharge. The phone will show no response — no logo, no charging indicator — even when plugged in. Connect the phone to a wall charger (not a USB hub) and leave it for 20–30 minutes without pressing the power button; the BMS needs a trickle current at around 3.0V before it re-enables normal charge flow. Once the screen shows the charging indicator, the cell is out of lockout and will charge normally to 3.85V.

Compatible Models

A3 A3 Dual SIM A3 Dual SIM TD-LTE CPH1837 PADT00 PADM00

Replaces Part Numbers

BLP661

Technical Specifications

Voltage3.85V
Amp Hours3300mAh
Capacity3300mAh
Rate12.71Wh
Net Weight46.4g /1.64 oz
Gross Weight81g /2.86 oz
Approximate Weight81g /2.86 oz
Dimension 81.52 x 64.62 x 3.65mm

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

My Oppo A3 shows the wrong battery percentage after I put in the new BLP661 — it jumped from 60% to 15% without warning. What's happening?

The fuel gauge IC inside the A3 stores a learned discharge curve from the old, degraded cell — it has no data for the new cell's actual voltage behaviour. Until it re-maps, the percentage display can jump or stall because the IC is comparing real-time voltage against the wrong reference. Run one uninterrupted full cycle: drain the phone to automatic shutdown, then charge straight to 100% without unplugging. After that single cycle the coulomb counter recalibrates and the percentage tracking stabilises.

Fast charging stopped working on my Oppo A3 right after I installed the replacement battery — it only charges slowly now. Is the new cell defective?

This is normal on the first cycle after a cell swap. The phone's charge IC applies a handshake protocol before enabling high-current fast charging, and on a fresh cell with no charge history the IC defaults to a conservative trickle until it confirms the BMS is responding correctly. Charge the phone fully once at standard speed without interruption. On the second charge cycle, reconnect the charger — the fast-charge protocol should re-engage once the IC has logged a complete charge event from the new cell.

The Oppo A3 feels noticeably warm near the battery during the first few charges with the BLP661. Should I be concerned?

A new Li-Polymer cell has higher internal impedance than a broken-in cell, so the charge IC pushes voltage across more resistance during early cycles — that converts more energy to heat than you'd see on a well-cycled cell. The warmth is concentrated near the battery tray, not the USB port or processor area. It typically reduces after three to five full charge cycles as the cell's impedance settles. If the back of the phone becomes hot to the touch or the phone throttles performance, check that the adhesive securing the cell is not trapping heat against the rear cover.

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