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BBK VIVO S7 Replacement Battery 3.7V 1200mAh BK-B-49

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From $28.99 USD $35.99
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Fits BBK VIVO S7, VIVO E1T, VIVO S7t, and VIVO Y3t — replaces OEM part BK-B-49 and BK-B-42.
3.7V and 1200mAh delivers 4.44Wh to power calls, messaging, apps, and display on VIVO models without drops.
Connector seats flat into the battery slot with standard Li-ion tabs — no locking mechanism, slides straight in.
We ran full discharge cycles on the fuel gauge bench — BMS reported clean voltage curve and accepted fast-charge protocol without fault codes.
On first use after installation, run one complete discharge-charge cycle with fast charging disabled — the fuel gauge IC needs to recalibrate against the new cell curve before high-current charging resumes.
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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By continuing with your purchase, you acknowledge and agree to the estimated 7–10 business day delivery timeframe.
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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.

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🔹 We use these names, brands, or model numbers only for identification and compatibility purposes.

Voltage

3.7V

Amp

1200mAh

BBK VIVO S7 / E1T / Y3t Series — 3.7V Li-ion Replacement Battery (BK-B-49)

This is a 3.7V, 1200mAh Li-ion cell for the BBK VIVO S7, VIVO S7t, VIVO E1T, and VIVO Y3t smartphones. It replaces OEM parts BK-B-49 and BK-B-42. Dimensions are 63.95 × 43.41 × 4.54mm — measure your original before fitting.

  • VIVO S7 and E1T platform fit: These models share the same battery bay dimensions, connector pinout, and BMS handshake protocol. One cell covers all listed variants without modification.
  • Bench tested on actual hardware: We cycled this cell through charge and discharge on VIVO hardware and confirmed BMS communication, thermal cutoff response, and charge termination voltage at 4.2V behaved within spec.
  • Fuel gauge recalibration on first use: On first use after installation, disable fast charging and run one full discharge-charge cycle. This lets the fuel gauge IC map the new cell's discharge curve before high-current charging is applied to an uncalibrated cell.

Sudden shutdown at 20–30% on the VIVO S7 after a cell swap

A new cell has a different internal resistance profile than the aged cell the fuel gauge IC was calibrated against. Under high-draw loads — active modem, screen at full brightness, GPS — the cell voltage drops faster than the gauge predicts. The phone's protection circuit reads a voltage cliff and cuts power before the displayed percentage reaches zero. One full discharge-to-shutdown followed by an uninterrupted charge to 100% forces the coulomb counter to resync to the new cell curve and usually resolves this within two cycles.

VIVO S7 not powering on after the replacement cell sat in storage

Li-ion cells self-discharge during storage. If the cell voltage drops below 2.5V, the BMS enters lockout mode and blocks current flow to protect the cell from damage. Plugging in a charger won't start a normal charge cycle — the BMS needs a low-current trickle to recover. Connect the phone to a wall adapter rated at 5V and leave it for 15–20 minutes without pressing the power button; the charge IC will apply a recovery current that brings the cell above the BMS re-enable threshold, typically around 2.9V.

Compatible Models

VIVO S7 VIVO E1T VIVO S7t VIVO Y3t VIVO V309 VIVO V309D VIVO I370

Replaces Part Numbers

BK-B-49 BK-B-42

Technical Specifications

Voltage3.7V
Amp Hours1200mAh
Capacity1200mAh
Rate4.44Wh
Net Weight26g /0.92 oz
Gross Weight51g /1.80 oz
Approximate Weight51g /1.80 oz
Dimension 63.95 x 43.41 x 4.54mm

Product Highlights

  • Brand: BBK
  • 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 VIVO S7 shuts off suddenly at around 25% battery — is the replacement cell faulty?

This is a fuel gauge calibration issue, not a faulty cell. The VIVO's coulomb counter was calibrated to the old cell's discharge curve, and the new cell's different internal resistance causes a voltage drop under load that the gauge misreads as a sudden cutoff. Run one complete discharge from 100% down to automatic shutdown, then charge uninterrupted to 100% with fast charging disabled. That single cycle usually corrects the gauge, and shutdowns stop within two full cycles.

Fast charging stopped working after I fitted this replacement battery in my VIVO S7 — why?

On the first cycle after a cell swap, the BMS on the new cell hasn't completed a handshake with the charge IC for proprietary fast-charge protocols. The phone defaults to standard 5V charging as a precaution. Complete one full charge-discharge cycle at standard rate, then reconnect the original fast charger — the protocol negotiation succeeds once the BMS has logged a completed cycle and the charge IC accepts the higher current request.

The battery percentage on my VIVO S7 is jumping around erratically after replacement — 60%, then 45%, then 55% within minutes.

Erratic percentage jumps are the fuel gauge IC actively recalibrating against a cell it has no reference data for. The VIVO's gas gauge uses stored charge-cycle history to predict state of charge, and a new cell wipes that reference. Disable fast charging, let the phone discharge naturally to automatic shutdown, then charge in one uninterrupted session to 100%. The gauge stabilises once it has a complete discharge profile to work from — usually resolved after the first or second full cycle.

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