During the golden age of portable digital audio, Sharp’s MiniDisc (MD) players were renowned for their crisp recording capabilities and pocket-sized portability. At the heart of many 1999-era MD players sat the Sharp AD-T51BT—a compact, rechargeable Lithium-ion “gumstick” battery. Despite being nearly thirty years old, this unassuming power source remains a critical replacement part for vintage audio enthusiasts restoring classic MD gear today.
Key Specifications
- Type: Lithium-ion (Li-ion) Gumstick Battery
- Nominal Voltage: 3.7 V (Range: 3.6–3.8 V)
- Capacity: 800 mAh (Original rating; modern replacements often range from 700–1500 mAh)
- Dimensions: Approx. 68 mm (L) × 25.2 mm (W) × 6.7 mm (H)
- Design: Slim, rectangular “gumstick” form factor for easy insertion into portable MD units.
The AD-T51BT is cross-compatible with other Sharp batteries like the AD-S30BT, AD-S31BT, and AD-T50BT; however, the T51BT is notably slimmer to fit specific chassis designs.
Compatible Models
The AD-T51BT battery was originally bundled with the following Sharp MiniDisc players:
- MD-MT821 (Released Feb 1999)
- MD-MT831 (Released Aug 1999)
- MD-ST531 / MD-ST631 (Released Sept 1999)
Replacement batteries are also compatible with a wider range of Sharp MD portables, including:
- MD-MS Series: MS701, MS702, MS722
- MD-SS Series: SS322, SS421
- MD-ST Series: ST521, ST501
- And select other models that originally utilized the AD-S31BT / AD-T50BT battery packs.
After decades of use, original AD-T51BT batteries inevitably degrade and lose their capacity. Today, affordable third-party replacements allow these beloved players to continue serving collectors, musicians, and nostalgia seekers. Whether you are reviving a pocket recorder for live sessions or simply want to enjoy the warm, smooth sound of a MiniDisc, the AD-T51BT is your essential power companion.