Cycling & fitness
Polar H9 battery
1 × 3V lithium coin cell
How to replace it
| How to open | Lever battery cover open using the clip on the strap |
|---|---|
| Orientation | Positive (+) side downwards (inside the cover) |
| Notes | Use only CR2025. Ensure cover snaps closed for waterproofness. |
| Tools | Strap clip (included) |
| Seal / O-ring | Red silicone sealing ring (O-ring 20.0 × 0.90) must be intact — replace if damaged |
| Re-pair / reset | Yes |
| Re-pair after change | Yes |
| Access | Tool-free |
| Gasket / O-ring present | Yes |
Important
- CR2025 only
- Do not substitute CR2032 — Polar specifies CR2025 only.
- Re-pairing may be required after battery change on H9 firmware earlier than 1.2.1.
Sources
Helpful for this device
Optional tools for opening, testing or charging — separate from the battery answer.
- Coin cell / button cell battery tester
Quick check of CR / LR / SR button and coin cells before fitting
- Fluke 101 Digital Multimeter
Accurate open-circuit voltage and basic electrical checks
- Digital multimeter
Measure open-circuit voltage and general electronics checks
New battery but still not working?
A fresh 1 × CR2025 should restore Polar H9 if the battery was the problem. Work through the checks below before replacing the device.
- Check orientation
Confirm the cell is seated correctly: Positive (+) side downwards (inside the cover)
- Check the battery type
This device needs 1 × CR2025 (lithium). Rechargeable cells are not supported for this device. Same size does not always mean the same battery.
- Check known model-specific issues
Re-pairing or a short reset may be required after a battery change. Red silicone sealing ring (O-ring 20.0 × 0.90) must be intact — replace if damaged CR2025 only Do not substitute CR2032 — Polar specifies CR2025 only. Re-pairing may be required after battery change on H9 firmware earlier than 1.2.1.
- Confirm the battery itself
For most coin cells, fitting a known-good fresh cell of the correct code is simpler than capacity testing.
- Still not responding?
If a correct, fresh battery installed properly does not restore the device, the fault may be elsewhere — the device may need service or replacement.