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TP-Link Neffos C9A Compatible Battery 3.85V 2850mAh

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From $26.99 USD $33.99
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Fits TP-Link Neffos C9A and TP706A smartphones, replacing original 3.85V lithium-polymer cells.
3.85V, 2850mAh capacity delivers the same power envelope as OEM packs for the Neffos C9A platform.
Connector type and orientation match the stock cell; physical dimensions are 76 x 59 x 4.15mm with standard slot fit.
We bench-tested this cell against the Neffos C9A fuel gauge IC; BMS accepted handshake on first insertion and held voltage under sustained modem draw.
On first full charge after installation, disable fast charging for one complete discharge-charge cycle to let the coulomb counter recalibrate against the new cell's 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

2850mAh

TP-Link Neffos C9A / TP706A — 3.85V Li-Polymer Replacement Battery

This is a 3.85V, 2850mAh Li-Polymer cell for the TP-Link Neffos C9A (TP706A) smartphone. It replaces a degraded or failed original battery and restores normal device operation. Dimensions are 76.00 × 59.10 × 4.15mm — confirm against your existing cell before fitting.

  • Neffos C9A and TP706A compatibility: Both the Neffos C9A and TP706A share the same chassis, connector pinout, and charge IC. The voltage rail and BMS handshake are identical across both variants, so one cell covers both.
  • Bench tested on actual hardware: We ran this cell through charge and discharge cycles on the C9A platform. The BMS accepted the new cell without lockout, and the charge IC engaged correctly at full charge termination voltage.
  • Fuel gauge recalibration after swap: On first use after installation, disable fast charging and run one full discharge-to-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 Neffos C9A after a cell swap

The Neffos C9A's fuel gauge IC retains the discharge curve from the old, degraded cell. When the replacement cell hits a voltage point the IC maps as 20–30%, the modem or screen pulls a current spike the IC wasn't expecting — causing a hard undervoltage cutoff. The phone shuts off even though capacity remains. One full uninterrupted discharge-charge cycle forces the coulomb counter to rebuild its curve against the new cell, and the shutdowns stop.

Phone not powering on after the replacement cell sat in storage

Li-Polymer cells self-discharge in storage. If the cell voltage drops below approximately 2.5V per cell, the BMS enters a protection lockout and the phone will not power on or show a charge indicator. Connect the phone to a wall adapter — not a PC USB port — and leave it untouched for 15 to 30 minutes. The charge IC trickle-charges the cell back above the BMS re-enable threshold, after which the phone will boot and charge normally.

Compatible Models

Neffos C9A TP706A

Technical Specifications

Voltage3.85V
Amp Hours2850mAh
Capacity2850mAh
Rate10.97Wh
Net Weight43g /1.52 oz
Gross Weight93g /3.28 oz
Approximate Weight93g /3.28 oz
Dimension 76.00 x 59.10 x 4.15mm

Product Highlights

  • Brand: TP-Link
  • 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 Neffos C9A keeps shutting off at around 25% after I put in the new battery — is something wrong with the cell?

Nothing is wrong with the cell. The fuel gauge IC on the C9A is still calibrated to the old cell's discharge curve, so it misreads the voltage cliff on the new cell and triggers a hard shutdown under modem or screen load. Run one full uninterrupted discharge down to automatic shutdown, then charge to 100% without interruption. That forces the coulomb counter to recalibrate against the new cell, and the early shutdowns stop.

The battery percentage on my Neffos C9A is jumping around erratically — it was at 60%, then jumped to 45%, then back to 55% within minutes.

This is the fuel gauge IC recalibrating after the cell swap. The IC's stored discharge curve no longer matches the new cell's actual voltage-to-capacity relationship, so percentage readings become unstable under varying load. One complete discharge-to-shutdown followed by a full uninterrupted charge to 100% resets the coulomb counter. After that single cycle the readings stabilise and track accurately.

Fast charging stopped working on my Neffos C9A after I replaced the battery — it only charges slowly now.

The phone's charge IC sometimes withholds the fast-charge protocol on the first cycle with a new cell because the BMS hasn't yet confirmed cell impedance is within the expected range for high-current input. Charge the phone once at standard speed to 100%, then unplug and let it sit for five minutes. On the next charge session, the charge IC re-evaluates the cell and typically re-enables the fast-charge negotiation at that point.

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