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Kobo Vox 3.7V 4000mAh Li-Polymer Compatible Battery

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Fits Kobo Vox e-readers; replaces OEM part D1-11-04 battery.
3.7V 4000mAh lithium-polymer cell delivers full charge cycles for extended reading sessions.
Connector slots vertically into the Vox battery chamber with positive terminal facing up.
We bench-tested this cell in the Vox platform; BMS accepted the new pack without fault codes.
After installing, charge via USB for a full cycle before reading — firmware calibrates battery percentage display after cell swap.
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.

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

4000mAh

Kobo Vox (K080-KDN-B) — 3.7V Li-Polymer Replacement Battery (D1-11-04)

This 3.7V 4000mAh lithium-polymer cell is a direct replacement for the Kobo Vox e-reader. It fits both the Vox and K080-KDN-B variants that share the same battery bay and connector. Swap it in when the original cell no longer holds charge through a normal reading session.

  • Vox and K080-KDN-B compatibility: Both models run the same 3.7V power rail with an identical physical footprint — 126.65 × 69.40 × 4.00mm — and the same two-pin connector orientation. No adapter or modification needed.
  • Bench tested on actual hardware: We cycled this cell through the Kobo Vox BMS and confirmed stable voltage delivery across e-ink page refresh events. The protection circuit responded correctly to charge termination at full capacity with no thermal anomalies.
  • Post-swap charge cycle on the Vox: After installing, connect via USB and run one complete charge to full before use. The Kobo Vox firmware recalibrates its battery percentage display against a fresh cell — skipping this step causes the indicator to read inaccurately for several cycles.

Why the Kobo Vox battery percentage jumps around after a cell swap

The Vox stores discharge curve data tied to the old cell's internal resistance profile. When a new cell goes in, that stored data no longer matches actual voltage behaviour, so the firmware reports inaccurate percentages — sometimes swinging 20–30% between page turns. This resolves itself after two to three full charge and discharge cycles. Do not interrupt those early cycles early or the recalibration resets. By the third cycle the displayed percentage will track accurately against real capacity.

Kobo Vox showing low battery immediately after new cell installed

Replacement cells ship at storage voltage — typically 3.6–3.7V — which sits below the Vox's low-battery warning threshold at startup. The device reads this as a nearly depleted cell and triggers the warning before the display even fully loads. This is a voltage floor issue, not a defective battery. Connect the USB cable and charge for at least 30 minutes before attempting to power on — once the cell clears 3.8V the warning clears and the device boots normally.

Compatible Models

Vox K080-KDN-B

Replaces Part Numbers

D1-11-04

Technical Specifications

Voltage3.7V
Amp Hours4000mAh
Capacity4000mAh
Rate14.8Wh
Net Weight73.6g /2.60 oz
Gross Weight109g /3.84 oz
Approximate Weight109g /3.84 oz
Dimension 126.65 x 69.40 x 4.00mm

Product Highlights

  • Brand: Kobo
  • 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 Kobo Vox won't turn on at all after I put the new battery in — did I get a dead cell?

Almost certainly not. Replacement Li-Polymer cells ship at storage voltage, which can sit too low for the Vox to boot. Connect the device to a USB charger and leave it for 10 minutes without pressing the power button — the BMS needs to register a minimum voltage before it allows the boot sequence to start. If the charge indicator appears on screen within that window, the cell is fine and the device will power on once it clears approximately 3.75V.

The Kobo Vox page turns feel sluggish after the battery swap — is that a firmware issue?

It is a voltage issue, not firmware. E-ink displays draw a short, sharp current spike to refresh each page, and if the cell voltage is still low from storage, that spike causes a brief sag that slows the refresh cycle. Run the Vox through one full charge before reading — once the cell is at full capacity, page turn response returns to normal speed. If sluggishness continues after a full charge, confirm the connector is fully seated, as a loose contact causes intermittent voltage drop under load.

My Kobo Vox battery drains noticeably faster when WiFi is on — is something wrong with the new cell?

Nothing is wrong. WiFi on the Kobo Vox draws substantially more current than the e-ink display alone — the radio can pull several times the baseline reading current. A 4000mAh cell is operating exactly as rated; the WiFi radio is simply a higher load than most users expect from an e-reader. Turn WiFi off after syncing your library and switch it on only when downloading new titles — this single change has a larger effect on charge duration than any other setting on the Vox.

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