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HE403 AT&T Fusion 5G Replacement Battery 3.87V 4600mAh

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From $35.99 USD $44.99
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Fits AT&T Fusion 5G smartphone, replaces OEM part number HE403.
3.87V lithium-polymer cell with 4600mAh capacity delivers 17.8Wh to the Fusion 5G's processor, modem, and display load.
Connector seats flush into the battery slot with no locking tab — orientation marked on the cell body.
We cycled this pack on the EA211005 board; BMS accepted charge current at 2A without fault codes or thermal event.
On first use after installation, disable fast charging for one complete discharge-charge cycle so the fuel gauge IC recalibrates 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 5 – 8 business days to your doorstep.

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

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⚠️ 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

3.87V

Amp

4600mAh

AT&T Fusion 5G — 3.87V Li-Polymer Replacement Battery (HE403)

This is a 3.87V, 4600mAh Li-Polymer replacement battery for the AT&T Fusion 5G smartphone. It fits models EA211005 and EA211001 and replaces OEM part number HE403. It powers the display, processor, and wireless radios at the same voltage the phone's charge IC expects.

  • Fusion 5G platform fit: The EA211005 and EA211001 share the same battery bay geometry, connector pin-out, and 3.87V nominal rail. The charge IC and BMS handshake protocol are identical across both variants, so one cell covers both.
  • Bench tested on actual hardware: We cycled this cell on the Fusion 5G platform and confirmed the BMS accepted charge handshake on first power-on, held voltage above the 3.4V cutoff threshold under simultaneous 5G modem and display load, and logged no protection-circuit trips during discharge.
  • Fuel gauge recalibration on first use: On first use after installation, disable fast charging for one complete discharge-charge cycle. This lets the fuel gauge IC recalibrate against the new cell's discharge curve before high-current charging pushes current into an uncalibrated cell.

Sudden shutdown at 20–30% on the Fusion 5G after a cell swap

This happens because the fuel gauge IC was calibrated to the old cell's discharge curve. The new cell hits a voltage cliff — it cannot sustain voltage under simultaneous modem and screen load — even though the reported percentage looks safe. The phone interprets the voltage drop as an emergency and cuts power. One full discharge-charge cycle without fast charging forces the coulomb counter to remap against the new cell and resolves this.

USB-PD fast charge not activating after replacement

On the first cycle after a cell swap, the charge IC may not complete the USB-PD negotiation handshake with the new BMS. The phone defaults to standard 5W charging as a safety fallback. Plug the phone in, let it reach 100% on standard charge, then reboot. The charge IC re-runs BMS negotiation on the next plug-in event and fast charge resumes at rated wattage.

Compatible Models

Fusion 5G EA211005 EA211001

Replaces Part Numbers

HE403

Technical Specifications

Voltage3.87V
Amp Hours4600mAh
Capacity4600mAh
Rate17.8Wh
Net Weight62g /2.19 oz
Gross Weight112g /3.95 oz
Approximate Weight112g /3.95 oz
Dimension 84.50 x 65.40 x 5.00mm

Product Highlights

  • Brand: AT&T
  • 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 AT&T Fusion 5G keeps shutting off around 25% after I put the new battery in — is that normal?

Yes, and it fixes itself. The fuel gauge IC is still running the discharge curve from your old cell, so it misreads where the voltage cliff actually sits on the new one. Under 5G modem or screen load, voltage drops faster than the IC expects and the phone cuts power as a protection measure. Do one full discharge to 0% and a full charge to 100% with fast charging turned off — the coulomb counter remaps to the new cell after that cycle.

The phone won't turn on at all after the replacement battery sat in a drawer for a few months before I installed it — what happened?

Li-Polymer cells self-discharge in storage, and if the cell dropped below 2.5V the BMS entered lockout mode to prevent damage. The phone won't respond to a normal power button press in this state. Plug it into a wall charger — not a USB port — and leave it for 20–30 minutes without attempting to power it on. The charge IC trickle-charges the cell back above the 2.7V recovery threshold, after which the BMS unlocks and the phone boots normally.

Battery percentage is jumping around erratically — going from 60% to 45% in seconds — on the Fusion 5G with the new cell.

The fuel gauge IC is recalibrating. It tracked capacity on the old cell for months and its internal model no longer matches the new cell's impedance and discharge profile. The jumps are the coulomb counter correcting itself in real time as it gathers new data. Run two full discharge-charge cycles with fast charging disabled and the reported percentage will stabilise.

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