SportDog SD-1225 Trainer Receiver Compatible Battery 7.4V 200mAh

SportDog SD-1225 / SD-1825 / SD-2525 / SD-3225 Trainer Receiver — 7.4V Li-Polymer Replacement Battery (SAC00-12544)

This is a 7.4V 200mAh Li-Polymer battery for SportDog remote trainer receiver collars. It fits the SD-1225, SD-1825, SD-2525, SD-3225, and nine additional SD-series receiver units that share the same SAC00-12544 cell format. Dimensions are 26.31 × 40.13 × 5.77mm — measure your original before ordering if you are unsure.

• SD-series receiver compatibility: These SportDog trainer receivers share a common cell footprint and BMS voltage threshold across the range. The 7.4V nominal rail matches the receiver's stimulation circuit requirements, and the flat Li-Polymer form factor fits the sealed collar housing without modification.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on an SD-series receiver and confirmed the BMS accepted the charge profile without tripping a protection cutoff. Charge termination occurred cleanly at 8.4V as expected for a 2S Li-Polymer pack.
• First charge after installation: SportDog receiver collars use a magnetic charging port with a short charge window — do not leave the collar on the charger beyond the indicator signal, as the small 200mAh cell reaches full charge quickly and the onboard protection circuit has limited overcharge headroom.

Why the SD-series receiver stops responding mid-session after a battery swap

A freshly installed Li-Polymer cell can sit at a surface charge that fools the receiver into showing a full indicator, then drops voltage sharply under the transmitter-signal load. This is a common first-cycle voltage sag on small-capacity polymer cells — the resting voltage and load voltage differ more than they do on larger packs. Running one full charge-discharge cycle before a training session stabilises the cell's internal resistance. After that cycle, voltage under load stays consistent and the receiver holds its link to the transmitter.

Receiver collar shows charging but returns to zero battery indicator immediately after removing from charger

This happens when the BMS protection circuit has tripped due to a deep-discharge event — the cell voltage dropped below the 6.0V cutoff threshold and the BMS latched off. Placing the collar on the charger applies voltage through the protection circuit but the cell itself is not accepting current. To attempt recovery, leave the collar connected to the SportDog magnetic charger for a full 60-minute session without interruption — some BMS units will trickle-charge at low current to bring the cell above the re-enable threshold of approximately 6.5V. If the indicator remains at zero after that, the cell will not recover and replacement is the correct next step.