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EB494865VO Samsung SPH-M840 Compatible Battery 3.7V 1900mAh

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Fits Samsung SPH-M840 and Galaxy Prevail II; replaces OEM battery EB494865VO.
Delivers 3.7V and 1900mAh — sufficient for full-day cellular and text operation.
Uses Samsung's standard micro-connector with friction-fit locking tab; no special tools required.
We tested this cell on an SPH-M840 bench unit — BMS accepted charge at 0.5A without fault codes.
On first full charge cycle, power the phone with Wi-Fi off to let the fuel gauge IC recalibrate against the new cell's voltage curve before returning to normal use.
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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

1900mAh

BoostMobile SPH-M840 / Galaxy Prevail II — 3.7V Li-ion Replacement Battery (EB494865VO)

This is a 3.7V Li-ion cell rated at 1900mAh (7.03Wh), built to the EB494865VO specification. It fits the Samsung SPH-M840 (Boost Mobile variant), Galaxy Prevail II, and Galaxy Prevail 2. Install it when the original cell no longer holds a charge through a standard day of calls, texts, and data.

  • SPH-M840 and Prevail II compatibility: These models share the same battery bay dimensions, 3.7V nominal rail, and connector footprint. The EB494865VO spec covers all variants listed — no adapter or modification needed.
  • Bench tested on actual hardware: We cycled this cell through charge and discharge on the SPH-M840 platform. The BMS accepted the charge handshake on the first cycle, and voltage held within the expected window under both idle and active modem load.
  • Fuel gauge recalibration on first use: After installation, disable fast charging if available and run one full discharge down to automatic shutoff before recharging to 100%. This gives the fuel gauge IC a clean reference curve against the new cell before the OS starts reporting percentages.

Sudden shutdown at 20–30% on the SPH-M840

This happens because the fuel gauge IC was calibrated to the old cell's discharge curve. When the new cell hits a voltage region the IC hasn't mapped yet, it misreads remaining capacity and the phone cuts out before the gauge reaches zero. The fix is a full discharge-recharge cycle with no interruptions. After one complete cycle, the coulomb counter resets its reference and percentage reporting stabilises.

Phone stays at 0% and won't power on after storage

If a Li-ion cell drops below roughly 2.5V from extended storage, the BMS enters a lockout state to prevent unsafe charging. The SPH-M840 will show nothing on screen or a flat-battery icon and refuse to boot. Connect the phone to a wall adapter — not a PC USB port — and leave it for 20–30 minutes without pressing the power button. The charge IC delivers a low-current trickle that brings the cell back above the BMS re-enable threshold, typically around 3.0V, after which normal charging resumes.

Compatible Models

SPH-M840 Galaxy Ring Galaxy Prevail II Galaxy Prevail 2

Replaces Part Numbers

EB494865VO

Technical Specifications

Voltage3.7V
Amp Hours1900mAh
Capacity1900mAh
Rate7.03Wh
Net Weight38g /1.34 oz
Gross Weight63g /2.22 oz
Approximate Weight63g /2.22 oz
Dimension 64.91 x 47.93 x 4.87mm

Product Highlights

  • Brand: BoostMobile
  • 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

Why does my SPH-M840 show the wrong battery percentage after putting in the new battery?

The fuel gauge IC on the SPH-M840 stores a learned discharge curve from the old cell. When a new cell goes in, that curve no longer matches and the reported percentage drifts — often reading full when the cell isn't, or dropping suddenly. Run one uninterrupted full discharge to automatic shutoff, then charge to 100% without unplugging early. After that single cycle the coulomb counter recalibrates to the new cell and percentage readings stabilise.

The phone gets noticeably warm near the battery during the first few charges — is something wrong?

This is expected on a new high-impedance cell. The charge IC pushes current into a cell with slightly higher internal resistance than the worn cell it replaced, and that resistance dissipates as heat. Warmth — not heat you can't hold your hand against — is normal for the first two or three charge cycles as the cell's impedance settles. If the phone becomes too hot to hold or charging stops mid-cycle, disconnect immediately and check that the battery contacts are seated flush with no debris on the terminals.

My SPH-M840 won't fast charge after swapping the battery — it's only trickling in slowly.

On the first cycle after a cell swap, the charge IC sometimes defaults to a lower current rate while it verifies the new cell's response. This is a protective behaviour, not a fault. Let that first charge complete fully without interrupting it. On the second charge cycle, the IC should step up to its normal rate. If slow charging persists beyond the second cycle, clean the battery contacts with a dry cotton swab and confirm the replacement cell is seated with no gap at the connector edge.

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Samsung SPH-M840 Replacement Battery, 3.7V, 1900mAh, Li-ion 1

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