Size 312 vs Size 13 hearing aid battery
Not interchangeable. Both are 7.9 mm in diameter but Size 13 is 5.4 mm tall while Size 312 is 3.6 mm tall. The Size 312 will rattle and lose contact in a Size 13 compartment. A Size 13 will not fit in a Size 312 door.
Side-by-side comparison
| Property | Size 312 | Size 13 |
|---|---|---|
| Tab color | Brown | Orange |
| IEC code | PR41 | PR48 |
| Diameter | 7.9 mm | 7.9 mm |
| Height | 3.6 mm | 5.4 mm |
| Capacity | ~175 mAh | ~310 mAh |
| Typical runtime | 3–10 days | 6–14 days |
| Typical aid style | RIC, mini BTE | BTE, full ITE |
Verdict
Do not substitute one for the other. Although the diameters are identical, the different heights mean neither fits in the other's compartment correctly. Always check your hearing aid's battery door or documentation for the correct size number, or look at the color of the tab on the battery being replaced.
How to tell them apart
- Tab color: brown = 312, orange = 13. The color code is universal across all major brands.
- Height: place both on a table. The 13 is visibly taller (5.4 mm vs 3.6 mm).
- Size printed on cell: "312" or "13" is almost always printed on the face of the battery.
Which lasts longer?
Size 13 at ~310 mAh has nearly double the capacity of Size 312 at ~175 mAh, so it will last roughly twice as long in equivalent usage. The tradeoff is that Size 13 requires a larger battery compartment.