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Optus Mytab Li3734T42P3hC86049 Compatible Battery 3.7V 3400mAh

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Fits Optus Mytab tablet; replaces OEM part numbers Li3734T42P3hC86049 and SBC791.
3.7V, 3400mAh capacity delivers 12.58Wh — sufficient for full-day tablet use without midday drain.
Connector and orientation match Mytab slot exactly; no adapter or modification needed for installation.
We bench-tested this cell in the Mytab charge circuit; BMS accepted handshake on first insertion without fault.
After installation, run one full discharge to automatic shutoff then charge uninterrupted to 100% — this resets the fuel gauge IC calibration against the new cell and resolves inaccurate percentage display.
Extended delivery time

Available by SPECIAL ORDER. Delivery for this product typically takes 2 weeks.

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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

3.7V

Amp

3400mAh

Optus Mytab — 3.7V Li-ion Replacement Battery (Li3734T42P3hC86049)

This is a 3.7V Li-ion replacement battery rated at 3400mAh (12.58Wh) for the Optus Mytab tablet. It fits where the original cell sits and connects to the same BMS circuitry on the motherboard. Install this when the original battery no longer holds a usable charge or fails to power the tablet on.

  • Mytab fitment: The Mytab uses a single-cell Li-ion pack at 3.7V nominal. The connector pinout and PCB protection circuit match the OEM spec — the tablet's charge IC negotiates with the cell directly, so voltage and connector alignment both matter here.
  • Bench tested on actual hardware: We ran this cell through charge and discharge cycles on the bench. The BMS responded correctly at both low-voltage cutoff and full-charge termination, with no unexpected trips during load transitions.
  • Fuel gauge recalibration after swap: After fitting the new cell, run the tablet down to automatic shutoff, then charge uninterrupted to 100%. This forces the fuel gauge IC to recalibrate against the new cell's actual capacity curve and clears the inaccurate percentage reading that appears after a battery swap.

Mytab shutting down at 15–25% remaining

The Mytab's fuel gauge IC holds a learned voltage curve from the old, degraded cell. When a new cell is installed, the IC still expects the old cell's voltage sag profile at low charge states. Under combined display and WiFi load, voltage drops faster than the IC predicts, triggering a premature shutdown. Run one full discharge-to-shutoff followed by an uninterrupted charge to 100% — after that cycle, the IC recalibrates and the shutoff threshold normalises around 3.3V.

Fast charging not available after battery replacement

Some Mytab units require the charge IC to complete at least one accepted charge cycle before re-enabling fast charge negotiation via USB-PD. After a battery swap, the IC may default to standard 5V charging until it confirms the new cell's parameters. Plug in using the original charger and cable and allow a full charge to complete without interruption. After that first cycle, fast charge should resume on the next connection.

Compatible Models

Mytab

Replaces Part Numbers

Li3734T42P3hC86049 SBC791

Technical Specifications

Voltage3.7V
Amp Hours3400mAh
Capacity3400mAh
Rate12.58Wh
Net Weight77g /2.72 oz
Gross Weight112g /3.95 oz
Approximate Weight112g /3.95 oz
Dimension 127.70 x 60.13 x 4.67mm

Product Highlights

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

Frequently Asked Questions

My Optus Mytab is showing 80% battery but just switched off — why?

The fuel gauge IC on the Mytab is still calibrated to the voltage curve of the old, worn cell. A new cell holds voltage higher for longer then drops steeply, which the IC misreads as a sudden cutoff event. Run the tablet down to automatic shutoff once, then charge uninterrupted to 100%. That single cycle resets the calibration and the shutoff behaviour stops.

The battery percentage on my Mytab is jumping around — it went from 60% to 30% without warning.

This is fuel gauge drift — the IC's stored capacity map no longer matches the new cell's actual discharge curve. It reads voltage correctly but maps it to the wrong percentage. Do one full discharge to automatic shutoff followed by a full uninterrupted charge to 100%. After that cycle, the percentage display tracks the real charge state accurately.

My Mytab feels warm on the back while charging after the battery swap — is that a problem?

Mild warmth during the first few charge cycles after a swap is normal. The charge IC on the Mytab runs a conditioning pass on a new cell, which generates slightly more heat than steady-state charging on a broken-in cell. If the tablet becomes hot to the touch or the charging stops before 100%, disconnect and check the cable and charger output — it should be 5V at the rated current for that adapter.

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