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BLU D550 Replacement Battery 3.7V 2200mAh C766205220T

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From $23.99 USD $29.99
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Fits BLU D550, D550A, D551A, and Studio 5.3 smartphones; replaces OEM battery C766205220T.
3.7V, 2200mAh lithium-ion cell delivers the capacity your D550 needs to sustain modem and display drain through a full day.
Connector solders directly to the phone motherboard; no slot or tab — physical fit is fixed once installed.
Bench testing showed the BMS accepted charge cycles without early cutoff; fuel gauge IC required one full discharge-recharge to sync with the new cell curve.
On first use after installation, disable fast charging for one complete discharge-charge cycle so the phone's coulomb counter recalibrates against this cell's discharge profile.
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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

3.7V

Amp

2200mAh

BLU D550 / Studio 5.3 Series — 3.7V Li-ion Replacement Battery (C766205220T)

This is a 3.7V, 2200mAh Li-ion replacement battery for the BLU D550, D550A, D551A, and Studio 5.3 smartphones. It replaces OEM part C766205220T. Swap it in when the original cell no longer holds a charge or the phone shuts down unexpectedly under load.

  • D550 / Studio 5.3 platform compatibility: The D550, D550A, D551A, and Studio 5.3 share the same battery bay dimensions, connector pinout, and BMS handshake requirements. All four accept the C766205220T cell format at 3.7V nominal.
  • Bench tested on actual hardware: We ran this cell through a full charge-discharge cycle on a D550 unit. The BMS accepted the cell without fault codes, charge termination triggered correctly at 4.2V, and low-voltage cutoff engaged at the expected threshold.
  • Fuel gauge recalibration on first use: Disable fast charging for the first complete discharge-charge cycle after installation. This lets the fuel gauge IC build an accurate discharge curve map against the new cell before high-current charging begins pushing current into an uncalibrated state.

Sudden shutdown at 20–30% on the D550 after a cell swap

The BLU D550's fuel gauge IC stores a discharge curve calibrated to the original cell. A new cell has a different internal resistance profile, so the IC misreads remaining capacity. When the modem fires a high-current burst — during a call or LTE data load — the cell voltage drops sharply below what the IC expects at that reported percentage. The phone interprets this as a critically low voltage event and shuts down even though the gauge still shows 20–30%. One full uninterrupted discharge to automatic shutdown followed by a full charge cycle resets the coulomb counter against the new cell curve.

Phone reports wrong battery percentage after installation

The fuel gauge IC on the D550 uses a stored model of the old cell's capacity curve to calculate percentage. A replacement cell with a different impedance signature throws off that model immediately. You'll see the percentage jump erratically or read higher than actual charge state. Run one complete discharge from 100% to automatic shutoff, then charge uninterrupted to 100% — this forces the IC to relearn the new cell's curve and stabilise the readout.

Compatible Models

D550 D550A D551A Studio 5.3 Studio 5.3 II

Replaces Part Numbers

C766205220T

Technical Specifications

Voltage3.7V
Amp Hours2200mAh
Capacity2200mAh
Rate8.14Wh
Net Weight46g /1.62 oz
Gross Weight81g /2.86 oz
Approximate Weight81g /2.86 oz
Dimension 76.90 x 62.25 x 4.90mm

Product Highlights

  • Brand: BLU
  • Manufacturer: CS
  • Series: X-Longer
  • Color: Black
  • Product Type: Li-ion
  • Battery Type: Li-ion
  • Warranty: 12 Months
  • Bulk Orders: sales@batteryweb.com

Frequently Asked Questions

My BLU D550 won't turn on at all after the replacement battery sat in storage — is the cell dead?

It's not dead — it's in BMS lockout. If the cell discharged below roughly 2.5V during storage, the battery management system blocks current flow to protect the cell from further damage. Connect the phone to a wall charger and leave it for 20–30 minutes without pressing the power button; the charge IC will trickle-charge the cell up past the lockout threshold before the BMS reopens. Once the screen shows a charge indicator, proceed with a normal full charge cycle.

Fast charging stopped working on the D550 after I put in the new battery — it only charges slowly now.

On the first cycle after a cell swap, the phone's charge controller may not complete the USB handshake required to step up to fast-charge current — it defaults to standard 5V/1A as a precaution against pushing high current into an unverified cell. Run one full slow charge from flat to 100%, then disconnect and reconnect the charger. The controller re-runs the protocol negotiation on the second cycle and fast charge typically resumes.

The D550 feels noticeably warm near the battery during the first few charges — is something wrong?

A new li-ion cell has higher internal impedance than a cell that has been through several cycles. During early charges, that resistance generates more heat as current flows through the cell. This is normal for the first three to five charge cycles and should reduce as the cell's impedance settles. If the phone stays hot to the touch beyond cycle five or the charger brick also runs unusually hot, check that the charge cable is delivering clean 5V — a failing cable can cause the charge IC to hunt between charge states and generate excess heat.

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