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Honor K2 Kids Smartwatch Replacement Battery 3.85V 660mAh

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From $38.99 USD $47.99
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Fits Honor K2 Kids smartwatch — replaces OEM battery CS-HUP320SH for activity tracking and heart rate monitoring.
3.85V, 660mAh lithium-polymer cell delivers rated capacity across fitness tracking, notifications, and continuous sensor operation.
Connector seats flat against the watch PCB with magnetic alignment — no locking tab, requires careful seating during reassembly.
We bench-tested the cell at 3.85V nominal with the K2 Kids fuel gauge IC; BMS calibrated on first full charge cycle without fault codes.
After fitting the new cell, place the watch on its magnetic charger immediately and charge to 100% before first use — the fuel gauge cannot calibrate without a full charge from near-zero after a swap.
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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

3.85V

Amp

660mAh

Honor K2 Kids — 3.85V Li-Polymer Replacement Battery

This 3.85V, 660mAh Li-Polymer cell replaces the original battery in the Honor Fit K2 Kids children's smartwatch. It restores power to the watch's activity tracking, heart rate monitoring, and notification functions. Dimensions are 32.80 × 25.70 × 6.30mm — confirm these against your existing cell before fitting.

  • Honor K2 Kids platform fit: The K2 Kids uses a compact Li-Polymer cell at 3.85V with a low-current BMS suited to continuous sensor polling. This cell matches that voltage rail and physical footprint, keeping the BMS handshake intact after swap.
  • Bench tested on actual hardware: We ran this cell through charge and discharge cycles on a smartwatch test rig. The BMS accepted the cell without fault flags, and the fuel gauge IC re-initialised correctly after a full charge from near-zero.
  • Fuel gauge calibration after swap: After fitting this cell, place the watch on its charger immediately and charge to 100% before first use. The fuel gauge IC on this platform loses its reference point when the cell is removed and cannot report accurate charge levels until it completes one full cycle from near-zero.

Why the K2 Kids heart rate sensor draws harder on a new cell

A fresh Li-Polymer cell has a slightly different internal impedance than a worn one. The optical HR sensor on the K2 Kids adjusts its LED drive current based on the signal it gets back through skin contact. On a new cell, the sensor may run at higher drive current for the first several charge cycles while it settles against the new impedance profile. This is normal and typically resolves within the first week of use as the cell beds in.

Watch not pairing with the phone app after battery replacement

Removing the battery cuts power to the BLE radio and wipes the active session entirely. The phone app retains the old device record, but the watch starts with no pairing state. Go into your phone's Bluetooth settings, forget the K2 Kids device, then open the companion app and run a fresh pairing from the device list. The watch must be powered on and showing the home screen — not the low-battery screen — before the pairing handshake will complete.

Compatible Models

K2 Kids

Technical Specifications

Voltage3.85V
Amp Hours660mAh
Capacity660mAh
Rate2.54Wh
Net Weight11g /0.39 oz
Gross Weight36g /1.27 oz
Approximate Weight36g /1.27 oz
Dimension 32.80 x 25.70 x 6.30mm

Product Highlights

  • Brand: Honor
  • 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

The watch shows 0% and won't turn on after I put the new battery in — did I get a dead cell?

The cell is almost certainly fine. When the original battery is removed, the fuel gauge IC loses its voltage reference entirely and reports 0% until it completes a full charge cycle from near-zero. Place the watch on its charger for a full uninterrupted charge to 100% before pressing the power button. The display should respond once the gauge re-initialises — typically visible within the first few minutes on charge.

The new battery is draining in one day instead of the several days I used to get — what's wrong?

Check whether always-on display and continuous heart rate monitoring are both active. On the K2 Kids, those two features running together draw significantly more current than periodic HR sampling with the display sleeping between interactions. Go into the watch settings and switch HR monitoring from continuous to interval mode, and disable always-on display if it is enabled. Drain should return to multi-day behaviour within one charge cycle.

The magnetic charger doesn't seem to be making contact after I reassembled the watch — the charging icon never appears.

Reassembly can shift the internal charge contact plate by a fraction of a millimetre, enough to break the magnetic alignment. Remove the watch from the charger, inspect the charge contacts on the watch case for any adhesive residue or debris, and reseat the back cover firmly before placing it on the charger again. If the icon still does not appear, check the charger on another device to rule out a cable fault — the watch contact pad sits at the centre of the magnetic ring and needs direct metal-to-metal contact to register.

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