Size 675 vs Size 312 hearing aid battery
Not interchangeable. Size 675 is 11.6 mm in diameter; Size 312 is 7.9 mm. They are completely different sizes in both diameter and height and serve different device categories.
Side-by-side comparison
| Property | Size 675 | Size 312 |
|---|---|---|
| Tab color | Blue | Brown |
| IEC code | PR44 | PR41 |
| Diameter | 11.6 mm | 7.9 mm |
| Height | 5.4 mm | 3.6 mm |
| Capacity | ~600 mAh | ~175 mAh |
| Typical runtime | 9–20 days | 3–10 days |
| Typical device | Power BTE, cochlear implant | RIC, mini BTE |
Verdict
These two sizes are not interchangeable. Size 675 will not physically fit in any device designed for Size 312. The 675's diameter is nearly 50% wider. They are used in an entirely different category of hearing device.
Which one do you need?
- Size 675 (blue tab) — if your aid is a large power BTE, especially for severe to profound hearing loss, or if you use a cochlear implant processor.
- Size 312 (brown tab) — if your aid is a small RIC/RITE or mini BTE device, which are the most common styles sold today.
If unsure, open the battery door and look at the empty compartment. The existing dead battery will be the fastest way to confirm the size.