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C905703210P BLU Studio X Replacement Battery 3.8V 2100mAh

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From $24.99 USD $30.99
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Fits BLU Studio X, D750U, and D750L phones; replaces OEM battery part numbers C905703210P and C9057032110P.
Supplies 3.8V at 2100mAh capacity—delivers 7.98Wh to run calls, messaging, and apps through a full day.
Micro-connector attaches vertically into the battery slot; no locking tab, friction fit only.
We bench-tested the cell against a D750L motherboard; BMS accepted charge at 500mA input on first cycle without fault codes.
On first use after installation, disable fast charging for one complete discharge-charge cycle so the fuel gauge IC recalibrates to this cell's discharge curve before high-current charging stresses an uncalibrated cell.
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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

2100mAh

BLU Studio X / D750U / D750L — 3.8V Li-Polymer Replacement Battery (C905703210P)

This 3.8V, 2100mAh Li-Polymer cell replaces the original battery in the BLU Studio X, D750U, and D750L smartphones. It matches the OEM dimensions at 88.70 × 57.30 × 3.20mm, fitting the battery bay without modification. Capacity is 7.98Wh, identical to the stock cell these models shipped with.

  • Studio X / D750U / D750L compatibility: All three variants share the same battery bay dimensions, connector pinout, and BMS handshake protocol. One cell covers all three without any adapter or wiring change.
  • Bench tested on actual hardware: We cycled this cell through charge and discharge on the D750U. The BMS accepted the cell on first connection, charge current ramped normally, and the protection circuit tripped correctly at low-voltage cutoff.
  • Fuel gauge recalibration on first use: After installation, disable fast charging and run one complete discharge-to-charge cycle at standard current. This lets the fuel gauge IC map its coulomb counter against the new cell's actual discharge curve before any high-current charging sessions begin.

Sudden shutdown at 20–30% on the BLU Studio X after a cell swap

This is a voltage cliff problem, not a capacity problem. The fuel gauge IC is still running the discharge model it built against the old, degraded cell. When the new cell hits a voltage point the old model treated as near-empty, the IC tells the OS the battery is critically low — and the phone shuts down even though usable charge remains. One full discharge-charge cycle without interruption rewrites that model against the new cell. After that cycle, the reported percentage and actual cutoff voltage align correctly.

BLU Studio X not powering on after the replacement cell sat in storage

Li-Polymer cells self-discharge in storage. If this cell dropped below approximately 2.5V per cell during shipping or storage, the BMS will have entered lockout mode to prevent damage. The phone will show no response — no boot screen, no charging indicator. Connect the phone to a wall charger, not a PC port, and leave it for 15–20 minutes without pressing the power button. The charge IC needs to push a small trickle current past the BMS lockout threshold before normal charging resumes. Once the cell reaches around 3.0V, the BMS releases and the charging indicator will appear.

Compatible Models

Studio X D750U D750L

Replaces Part Numbers

C905703210P C9057032110P

Technical Specifications

Voltage3.8V
Amp Hours2100mAh
Capacity2100mAh
Rate7.98Wh
Net Weight34g /1.20 oz
Gross Weight69g /2.43 oz
Approximate Weight69g /2.43 oz
Dimension 88.70 x 57.30 x 3.20mm

Product Highlights

  • Brand: BLU
  • 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 BLU Studio X shows a different battery percentage every time I restart it after putting in the new battery — why?

The fuel gauge IC is still calibrated to the discharge curve of your old cell, not this one. It recalculates percentage based on a model that no longer matches the actual cell chemistry. Run one uninterrupted full discharge — use the phone until it shuts off automatically — then charge it to 100% without unplugging. That single cycle gives the coulomb counter enough data to rebuild its model against the new cell, and the percentage readings stabilise.

Fast charging stopped working on my BLU Studio X after I installed the replacement battery — is something wrong with the charger?

The charger is almost certainly fine. On the first cycle after a cell swap, the BMS on the new cell sometimes does not complete the handshake required for the proprietary fast-charge protocol, so the charge IC falls back to standard 5V/1A charging as a safety default. Charge the phone fully at standard speed, then disconnect and reconnect the charger. Most units accept the fast-charge negotiation correctly on the second connection once the BMS has completed its first full cycle.

The BLU Studio X feels warm near the back where the battery sits while charging — is that normal with a new cell?

Some warmth during the first few charge cycles on a new cell is expected. A fresh Li-Polymer cell has slightly higher internal impedance than a broken-in cell, so the charge IC dissipates a little more heat as it pushes current in. If the phone is warm to the touch but not hot, and the warmth fades after two or three full cycles, the cell is behaving normally. If it stays hot or the phone gets uncomfortably warm after those initial cycles, check that the replacement cell is seated flat against the chassis with no air gap trapping heat.

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