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Yusun LA15 Replacement Battery 3.7V 1650mAh Li-ion

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From $28.99 USD $35.99
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Fits Yusun LA-I, i2, and i2c smartphones; replaces OEM part LA15.
3.7V at 1650mAh delivers 6.11Wh — matches the original cell's power output for calling, messaging, and app runtime.
Connector slides straight into the battery slot with no locking tab; orientation marked on the housing.
We cycled the pack on a bench charger at 0.5C; BMS accepted the charge handshake and held voltage curve under load.
On first use after installation, disable fast charging for one complete discharge-charge cycle to let the fuel gauge IC 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.

Discount: As a thank you for your patience, enjoy 5% off on your order
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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.

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🔹 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.

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

Voltage

3.7V

Amp

1650mAh

Yusun LA-I / i2 / i2c — 3.7V Li-ion Replacement Battery (LA15)

This is a 3.7V Li-ion cell rated at 1650mAh (6.11Wh), replacing the OEM LA15 battery in the Yusun LA-I, i2, and i2c smartphones. It fits the original battery bay without modification and connects to the same flex ribbon contact the phone's charge IC expects.

  • LA-I, i2, and i2c compatibility: All three models share the same 51.90 × 50.93 × 5.26mm battery footprint, identical 3.7V nominal voltage rail, and the same three-contact connector layout — so one cell covers the full platform without any wiring change.
  • Bench tested on actual hardware: We cycled this cell through charge and discharge on the LA-I platform and confirmed the BMS accepted the new cell without triggering a protection cutoff. The charge IC negotiated correctly and the cell held voltage within spec across the discharge curve.
  • Fuel gauge recalibration on first use: On first use after installation, disable fast charging and run one complete discharge-charge cycle. The fuel gauge IC is still calibrated to the old cell's discharge curve — this single cycle lets it re-anchor its coulomb counter to the new cell before high-current charging begins.

Why the LA-I reports wrong battery percentage after a cell swap

The phone's fuel gauge IC builds a discharge model based on the old cell's internal resistance and voltage curve. When a new cell goes in, the IC is still reading from its stored model, not the new cell's actual behaviour. This mismatch causes the percentage readout to jump ahead or fall behind real state of charge. One full discharge to 3.2V followed by a complete charge resets the coulomb counter and brings the gauge back into sync with the new cell.

Sudden shutdown at 20–30% on a freshly installed cell

This happens when the modem, display, or both spike current demand and the cell voltage drops sharply under load — faster than the fuel gauge's rolling average catches. The phone's protection circuit reads the voltage dip as critically low and cuts power before the displayed percentage reaches zero. It is not a faulty cell. Run the first cycle without any active fast-charge protocol, which keeps charge current steady and lets the voltage floor settle predictably. After two full cycles the gauge average stabilises and the cutoff point tracks closer to the real 3.0V floor.

Compatible Models

LA-I i2 i2c

Replaces Part Numbers

LA15

Technical Specifications

Voltage3.7V
Amp Hours1650mAh
Capacity1650mAh
Rate6.11Wh
Net Weight29g /1.02 oz
Gross Weight54g /1.90 oz
Approximate Weight54g /1.90 oz
Dimension 51.90 x 50.93 x 5.26mm

Product Highlights

  • Brand: Yusun
  • 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

The phone powered off at 25% and now won't turn back on — is the battery dead?

No. A sharp voltage sag under screen or modem load tripped the BMS protection cutoff before the display hit zero percent. Plug the phone into a charger and leave it for 15–20 minutes before pressing the power button — the charge IC needs to push the cell above the BMS re-enable threshold of roughly 3.0V per cell before the phone will boot.

Fast charging stopped working after I fitted the LA15 replacement — the phone only trickle charges now.

The USB-PD or proprietary fast-charge handshake sometimes fails on the first cycle with a new cell because the BMS presents a higher impedance than the charge IC expects. This causes the charger to fall back to standard 5V trickle mode as a safety default. Complete one full slow charge from flat to 100%, then reconnect the fast charger — the BMS impedance drops after the first full cycle and the handshake succeeds.

The battery percentage jumps erratically — it reads 60%, drops to 40%, then jumps back up.

The fuel gauge IC is still running the discharge model it built for the old degraded cell. A new cell has a different internal resistance profile, so the coulomb counter loses tracking and the percentage readout drifts. Discharge the phone fully until it shuts off automatically, then charge uninterrupted to 100% without removing the charger. That single cycle re-anchors the coulomb counter to the new cell's actual voltage curve.

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