SportDog SD-1275 Replacement Battery 7.4V 500mAh SDT54-16749

SportDog SportTrainer SD-1275 / SD-875 Series — 7.4V Li-Polymer Replacement Battery (SDT54-16749)

This 7.4V, 500mAh Li-Polymer battery replaces part number SDT54-16749 in SportDog SportTrainer e-collar receivers. It fits both the SD-1275 and SD-875 lines across Black and Orange Edition variants — eight collar models in total. The battery powers the receiver unit's stimulation, vibration, and tone output circuits.

• SD-1275 and SD-875 receiver compatibility: These collar models share the same receiver housing form factor, connector pinout, and BMS handshake protocol. A single battery cell covers both lines because SportDog standardised the power module across the SD-800 and SD-1200 platform generations.
• Bench tested on actual hardware: We cycled this cell through charge-discharge sequences on the receiver's internal BMS. The protection circuit engaged correctly at low-voltage cutoff and the charger accepted the cell without error flags on reconnection.
• Receiver charging port care — SD-1275 and SD-875: These collars charge through a proprietary magnetic contact point on the receiver body. After any battery swap, seat the receiver contacts fully and confirm the charger LED changes state within 10 seconds — if it does not, rotate the charger 180° on the contact pins before assuming a fault.

Why the SD-1275 receiver shows a full charge but delivers no stimulation output

A degraded Li-Polymer cell can hold a surface charge that satisfies the collar's voltage sensor at rest, but collapses under the current draw of the stimulation circuit. The SD-1275 receiver draws a short, sharp current pulse when it fires — a worn cell's internal resistance causes the voltage to sag below the BMS cutoff threshold during that pulse. The collar interprets this as a low-battery shutdown rather than a circuit fault. Replacing the cell with a fresh SDT54-16749 eliminates the sag, and the output circuit fires normally again.

Collar receiver won't power on after sitting unused for several months

Li-Polymer cells self-discharge during storage. If the SD-1275 or SD-875 receiver sat unused long enough, the cell voltage may have dropped below 3.0V per cell — the point at which most BMS circuits lock out charging entirely to prevent damage. Connect the magnetic charger and leave it for 20–30 minutes before pressing the power button; some BMS units trickle charge from this state before re-enabling the main charge path. If the charger LED never activates after 30 minutes, the cell has discharged past recovery and the replacement SDT54-16749 cell is the correct next step. After fitting the new cell, charge to full before first use — confirmed by a solid green LED on the charger.