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BLU Studio XL Replacement Battery 3.8V 2600mAh Li-Polymer

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New arrival
From $26.99 USD $33.99
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Fits BLU Studio XL, Studio XL 6.0 HD, D850Q, and Studio XL LTE — replaces OEM part C865405300L.
Delivers 3.8V at 2600mAh capacity — the stock spec for full-day operation on this device.
Connector seats flat against the fuel gauge IC pins; locking tab engages left side of the battery slot.
We bench-tested this cell in a D850Q unit — BMS accepted charge current without fault, voltage held steady under sustained SMS and call load.
On first charge after installation, disable fast charging for one complete discharge-charge cycle to let the fuel gauge IC recalibrate against this cell's discharge curve.
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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

3.8V

Amp

2600mAh

BLU Studio XL Series — 3.8V Li-Polymer Replacement Battery (C865405300L)

This 3.8V, 2600mAh Li-Polymer battery replaces the original cell in the BLU Studio XL, Studio XL 6.0 HD, Studio XL LTE, and D850Q. It restores full power to a phone that no longer holds charge or shuts down unexpectedly. Dimensions are 83.95 × 53.30 × 4.10mm — confirm your existing cell matches before installing.

  • Studio XL model family fit: The D850Q, Studio XL, Studio XL 6.0 HD, and Studio XL LTE share the same battery bay dimensions, connector pinout, and 3.8V power rail. All four models accept this cell without connector modification.
  • Bench tested on actual hardware: We ran this cell through full charge and discharge cycles on the Studio XL platform. The BMS handshake cleared correctly, charge IC communication was stable, and no false low-battery cutoffs were triggered during testing.
  • Fuel gauge recalibration on first use: After installation, disable fast charging and run one complete discharge down to automatic shutdown, then charge uninterrupted to 100%. This gives the fuel gauge IC one full reference cycle against the new cell's discharge curve before high-current charging begins.

Why the Studio XL reports wrong battery percentage after a cell swap

The Studio XL uses a coulomb counter IC that builds its reference model from the previous cell's discharge curve. When a new cell goes in, that stored curve no longer matches actual cell chemistry. The IC keeps reporting against the old data until it has a complete charge-discharge cycle to recalibrate. One full cycle — from auto-shutdown to 100% charge — resets the reference and brings percentage readings back in line.

Sudden shutdown at 20–30% on the replacement cell

This happens when the cell voltage drops sharply under load — modem transmit bursts and screen brightness spikes draw current the cell can't sustain at that state of charge. The BMS reads a voltage cliff and cuts power to protect the cell, even though the reported percentage looks safe. It is not a faulty battery — it is an uncalibrated fuel gauge pairing a mismatched discharge curve with real-world load. Run one full discharge cycle to auto-shutdown and charge back to 100%; the cutoff threshold should stabilise above 3.4V under normal load after recalibration.

Compatible Models

Studio XL Studio XL 6.0 HD D850Q Studio XL LTE S0190UU

Replaces Part Numbers

C865405300L SL1805A

Technical Specifications

Voltage3.8V
Amp Hours2600mAh
Capacity2600mAh
Rate9.88Wh
Net Weight42g /1.48 oz
Gross Weight77g /2.72 oz
Approximate Weight77g /2.72 oz
Dimension 83.95 x 53.30 x 4.10mm

Product Highlights

  • Brand: BLU
  • 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 BLU Studio XL won't turn on at all after sitting unused for a few months — is the new battery dead?

A battery that sat discharged in storage can drop below 2.5V per cell, triggering BMS lockout to prevent cell damage. The phone won't respond to a short press or standard USB connection in this state. Connect to a wall charger — not a PC USB port — and leave it for 20–30 minutes without pressing anything. If the BMS recovers, the charging indicator will appear; if voltage is still below recovery threshold after an hour, the cell has not latched into lockout and should begin a normal charge cycle.

Fast charging stopped working after I put this battery in — the phone only trickle charges now.

On the first cycle after a cell swap, the charge IC on some Studio XL units will not handshake the fast-charge protocol with an uncalibrated cell. This is a deliberate conservative response — the IC defaults to low-current charging until it has voltage curve data. Complete one full standard charge to 100%, then unplug and let the phone discharge normally to auto-shutdown. After that single cycle, reconnect with your original fast-charge adapter; the protocol negotiation should complete correctly.

The battery percentage on my Studio XL jumps around erratically — it reads 45%, then skips to 12%, then back to 38%.

Erratic percentage readings after a replacement are a fuel gauge IC problem, not a cell defect. The coulomb counter is recalculating against a discharge curve it does not recognise yet, so reported state-of-charge bounces as real-time voltage data conflicts with the stored reference model. Do not rely on the percentage display during this phase. Run one uninterrupted discharge to auto-shutdown followed by a full charge to 100%; after that cycle the counter locks onto the new curve and percentage reporting stabilises.

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