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Toshiba Genio E300 LAB503759C Replacement Battery 3.7V 1000mAh

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From $29.99 USD $36.99
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Fits Toshiba Genio E300, E310, E330, E335 and replaces OEM battery LAB503759C.
This 3.7V, 1000mAh Li-Polymer cell powers the PDA's CPU, RAM, and application state during field use.
Connector slides into the battery bay with a flat contact latch; orientation marked on the housing.
We bench-tested this cell in a Genio E330 — BMS accepted full charge in under two hours without fault codes.
Sync all open files and contacts to your host computer before removing the battery, as the PDA stores active data in RAM powered by this cell only.
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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

1000mAh

Toshiba Genio E300 Series — 3.7V Li-Polymer Replacement Battery (LAB503759C)

This is a 3.7V, 1000mAh Li-Polymer battery for the Toshiba Genio E300 line of PDA and Pocket PC handhelds. It replaces OEM part LAB503759C and fits the Genio E300, E310, E330, and E335. The cell measures 60.50 × 36.31 × 5.02mm and slots directly into the original battery bay.

  • Genio E300 series compatibility: The E300, E310, E330, and E335 share the same battery footprint, connector pinout, and BMS handshake protocol. One cell covers the full range without modification.
  • Bench tested on actual hardware: We cycled this cell through charge and discharge on the Genio E300 platform. The BMS negotiated correctly, voltage reporting in the system settings matched expected levels, and no fault flags were raised during the test.
  • RAM backup before battery removal: Sync all open data to your host computer before pulling the battery. The Genio E300 stores application state and open files in SRAM that is powered entirely by the main cell — cutting power without syncing first will erase unsaved data.

Why the Genio E300 loses contacts and calendar data after a battery swap

The Genio E300 uses battery-backed SRAM as its primary working memory. There is no onboard flash storage holding your active data — the battery is the only thing keeping that memory alive. The moment the cell drops below the SRAM hold voltage, the contents are gone. This is not a fault in the replacement battery; it is the architecture of the device. Always perform an ActiveSync backup to your PC before removing the old cell, then restore after fitting the new one.

Genio E300 stuck on boot screen after fitting new battery

A Li-Polymer cell shipped in storage state may arrive at 3.0V or below, which is under the minimum threshold the Genio E300 boot sequence requires to complete POST. The device powers on, reaches the Toshiba splash screen, and stalls — it is not a firmware or hardware fault. Connect the charger and leave it for at least 30 minutes before attempting to boot again. Once the cell reaches approximately 3.6V, the device will boot normally and proceed to the setup or main screen.

Compatible Models

Genio E300 Genio E310 Genio E330 Genio E335 Genio E340 Genio E350 Genio E355

Replaces Part Numbers

LAB503759C

Technical Specifications

Voltage3.7V
Amp Hours1000mAh
Capacity1000mAh
Rate3.7Wh
Net Weight23g /0.81 oz
Gross Weight48g /1.69 oz
Approximate Weight48g /1.69 oz
Dimension 60.50 x 36.31 x 5.02mm

Product Highlights

  • Brand: Toshiba
  • 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 Genio E300 shows a full charge but the battery drains much faster than it used to — is the new cell faulty?

This usually means the fuel gauge in the Genio E300 has not recalibrated to the new cell. The device reads state-of-charge from a counter that was tuned to the old, degraded battery. Run the new cell through two full charge-to-discharge cycles without interruption, then charge fully to 4.2V. The gauge will re-anchor to the new cell's actual capacity after that.

I lost all my contacts and apps the moment I swapped the battery — why did that happen?

The Genio E300 holds all active data in SRAM, which is powered continuously by the main battery. There is no secondary coin cell or flash backup for that memory. The instant the old battery disconnects, the SRAM contents are erased — this happens even if the swap takes only a few seconds. Before any future battery change, do a full ActiveSync sync to your PC, then restore from that backup after the new cell is fitted.

Wireless sync keeps dropping or running slowly right after I installed the replacement battery — what's going on?

The Genio E300's wireless radio is voltage-sensitive and starts throttling or dropping the connection when the cell is below about 3.7V. A new cell shipped in storage state may not be charged enough to sustain the radio at full power. Charge the device fully before attempting any wireless sync. If it still drops, check the battery indicator in Settings — if it reads below 80%, continue charging before retrying.

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