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Oppo A15 BLP817 Replacement Battery 3.85V 4150mAh

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From $26.99 USD $33.99
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Replaces BLP817 battery for Oppo A15, A15 2020, CPH2185, and A15S models.
3.85V nominal voltage, 4150mAh capacity — supplies full runtime on a single charge for daily use.
Connector solders directly to the motherboard; no physical locking tab or slot involved in this design.
We cycled the cell through five full charge-discharge runs on the Oppo A15 test rig — BMS accepted voltage handshake on cycle one, fuel gauge IC stabilized by cycle three.
On first use after installation, disable fast charging for one complete discharge-charge cycle — this recalibrates the fuel gauge IC against the new cell discharge curve before high-current charging.
Delivery time

This product ships directly from our Manufacturer’s Warehouse and is usually delivered within 5 – 8 business days to your doorstep.

Discount: As a thank you for your patience, enjoy 5% off on your order
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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

4150mAh

Oppo A15 / CPH2185 — 3.85V Li-Polymer Replacement Battery (BLP817)

This is a 3.85V, 4150mAh (15.98Wh) lithium-polymer cell replacing the OEM BLP817 battery in the Oppo A15 and A15S smartphones. It fits the CPH2185 model code and the A15 2020 variant. The connector, dimensions (88.00 × 64.15 × 4.00mm), and BMS pinout match the original factory specification.

  • A15 and A15S platform compatibility: Both the A15 and A15S share the CPH2185 platform chassis, the same fuel gauge IC wiring, and the identical BLP817 connector layout — one cell covers both handsets without modification.
  • Bench tested on actual hardware: We cycled this cell on a CPH2185 unit and confirmed the BMS handshake completes at first boot, the fuel gauge IC accepts the new cell, and charge termination triggers correctly at 4.35V.
  • First-cycle fast charge handling: On first use after installation, disable VOOC or fast charging for one full discharge-charge cycle. This lets the fuel gauge IC build an accurate discharge curve for the new cell before high-current charging is applied to an uncalibrated pack.

Why the A15 reports wrong battery percentage after a cell swap

The A15 uses a coulomb counter IC that builds its reference model against the original cell's discharge curve. When you install a new BLP817 cell, the IC still references the old degraded curve. This causes the reported percentage to be 10–20% off real capacity for the first few cycles. Run one complete discharge to the automatic shutdown point and charge to 100% without interruption — the IC resets its full-charge reference and the readings stabilise.

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

This happens when the modem or display draws a high current spike and the cell voltage drops below the BMS cutoff threshold before the fuel gauge IC registers the drop. On a freshly installed cell, the IC's low-voltage floor reference is still calibrated to the old cell's internal resistance. The BMS sees the voltage cliff first and cuts power while the OS is still showing 25%. After two full discharge-charge cycles, the IC recalibrates its voltage-to-capacity mapping and the early shutdowns stop.

Compatible Models

A15 A15 2020 CPH2185 A15S A16K

Replaces Part Numbers

BLP817

Technical Specifications

Voltage3.85V
Amp Hours4150mAh
Capacity4150mAh
Rate15.98Wh
Net Weight56.2g /1.98 oz
Gross Weight106.2g /3.75 oz
Approximate Weight106.2g /3.75 oz
Dimension 88.00 x 64.15 x 4.00mm

Product Highlights

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

Frequently Asked Questions

My Oppo A15 won't turn on at all after the replacement battery sat unused for a few months — is the cell dead?

The BLP817 cell most likely dropped below 2.5V in storage and the BMS has locked out to prevent damage. Plug the phone into a wall charger — not a PC USB port — and leave it for 30 minutes before attempting to power on. The charge IC trickle-charges a locked-out cell back into the normal operating window. If the charging indicator appears within that window, the cell is recovering; let it reach at least 3.6V before booting.

VOOC fast charging isn't working after I fitted the new BLP817 — the phone only slow-charges now.

The VOOC protocol requires a handshake between the charger, the charge IC, and the BMS on the new cell. On the first cycle after installation, the BMS often rejects the elevated current offer until it has completed one full standard charge. Use the original VOOC charger and cable, let the phone complete one slow charge to 100%, then unplug and recharge — the fast charge handshake should re-establish at that point.

The battery percentage on my A15 is jumping around erratically — it shows 60%, drops to 40%, then climbs back up without charging.

The coulomb counter IC is recalibrating against the new cell's discharge characteristics and hasn't yet mapped the voltage curve accurately. This is normal for the first two to three cycles after a cell replacement. Run the phone down to automatic shutdown, then charge uninterrupted to 100% twice in a row. The IC locks in a stable reference model after those full cycles and the percentage readings settle.

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