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Garmin Forerunner 245 Replacement Battery 3.8V 170mAh

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From $30.99 USD $38.99
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Fits Garmin Forerunner 245 and Forerunner 245 Music, replacing OEM part 361-00086-11.
3.8V, 170mAh Li-Polymer cell delivers the energy density this compact GPS watch requires for multi-day operation.
Connector seats flush into the proprietary Garmin dock with a single alignment post; no locking tab.
We charged this cell on a Forerunner 245 dock and logged normal BMS handshake with no fault codes or cutoff events.
After fitting, place the watch on its charger immediately and charge to 100% — the fuel gauge IC cannot calibrate without a full charge cycle after a 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.

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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

3.8V

Amp

170mAh

Garmin Forerunner 245 / 245 Music — 3.8V Li-Polymer Replacement Battery (361-00086-11)

This is a 3.8V, 170mAh Li-Polymer cell that fits the Garmin Forerunner 245 and Forerunner 245 Music GPS running watches. It replaces OEM part 361-00086-11 and sits behind the rear case on the same flex connector. Swap it when the original cell no longer holds a charge across a full training week.

  • Forerunner 245 and 245 Music compatibility: Both variants use the same 29.30 × 20.00 × 3.30mm cell footprint, identical voltage rail, and the same BMS handshake on the flex connector. No firmware difference affects this cell — the Music model's storage draws from the same battery circuit.
  • Bench tested on actual hardware: We ran this cell through the Forerunner 245's charge controller and confirmed the BMS accepted the new cell without fault flags. The fuel gauge IC re-registered correctly once a full charge cycle completed from near-zero.
  • Post-swap charge requirement for Forerunner 245: After fitting the new cell, place the watch on its magnetic charger immediately and charge it to 100% before first use. The fuel gauge IC on this platform loses its reference point when the cell is swapped — it cannot recalibrate without one full charge cycle from near-zero. Skip this step and the percentage readout will be inaccurate for days.

Why the Forerunner 245 shows 0% immediately after a battery swap

The Forerunner 245 uses a coulomb-counting fuel gauge IC that tracks charge state relative to a stored reference. When the cell is removed, that reference resets to zero. The watch has no way to measure the new cell's actual charge on insertion — it just sees an unknown state and defaults to 0%. This is not a fault with the replacement cell. Place the watch on charge immediately after reassembly and let it reach 100% without interruption. Once that full cycle completes, the fuel gauge sets a new reference and percentage readings will be accurate.

Watch not pairing with phone after battery replacement

Removing the battery cuts power to the BLE radio and drops the active Bluetooth session entirely. The phone retains the old device record but the watch starts with no session state — the two sides no longer agree on pairing keys. Open the Garmin Connect app, go to your device settings, and remove the Forerunner 245 from the paired devices list. Then re-initiate pairing from the watch's Bluetooth menu. The re-pair takes under two minutes and restores full sync.

Compatible Models

Forerunner 245 Forerunner 245 Music

Replaces Part Numbers

361-00086-11

Technical Specifications

Voltage3.8V
Amp Hours170mAh
Capacity170mAh
Rate0.65Wh
Net Weight5g /0.18 oz
Gross Weight30g /1.06 oz
Approximate Weight30g /1.06 oz
Dimension 29.30 x 20.00 x 3.30mm

Product Highlights

  • Brand: Garmin
  • 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 Forerunner 245 battery is draining in a single day after fitting the new cell — is something wrong?

This is normal for the first few charge cycles after a cell swap. The fuel gauge IC hasn't finished calibrating, so the watch may misread state-of-charge and behave erratically with power management. Run two full charge and discharge cycles without interruption. If drain remains at one day after that, check whether always-on display mode and continuous wrist heart rate monitoring are both active — together they draw significantly more current than the standard auto-sleep profile.

The magnetic charger isn't registering on the watch after I reassembled it — no charging icon appears.

The charge contacts on the Forerunner 245 rear case sit on small gold pads that can shift slightly during reassembly. Even a fraction of a millimetre misalignment breaks the circuit with the magnetic puck. Remove the charger, reseat the watch flat against the puck, and press lightly for three seconds. If no icon appears, inspect the rear pads for any adhesive residue or debris from the swap and clean with a dry cotton swab. A clean, flat contact should trigger the charging icon within ten seconds.

GPS is locking on slower than usual and the battery percentage is dropping fast during outdoor runs — what's happening?

A new Li-Polymer cell has a slightly different internal impedance than the worn cell it replaced. During the first week of use, the GPS radio's current draw hits the cell at an unfamiliar impedance and the fuel gauge over-reports drain. This settles after three to five full charge cycles as the BMS learns the cell's actual discharge curve. If slow GPS lock persists beyond that point, check that the watch's GPS mode is set to GPS-only rather than Multi-GNSS, which pulls measurably more current and extends the time-to-first-fix when the antenna is cold.

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