About this replacement
SportDog SR-225 / SR-225S / SR-225W Receiver — 3.7V Li-Polymer Replacement Battery (SAC54-13735)
This is a 3.7V, 160mAh lithium-polymer battery for the SportDog SR-225, SR-225S, and SR-225W receiver collars, plus the SportHunter 825 and compatible models. It replaces OEM part SAC54-13735. The SR-225 is a wireless dog training collar receiver — this battery powers the stimulation and tone circuits that respond to the handheld transmitter.
- SR-225 series and SportHunter 825 compatibility: These models share the same 3.7V cell footprint, connector pinout, and BMS handshake protocol. A single cell at this voltage and physical size — 34.00 × 19.80 × 3.20mm — covers the full receiver lineup without modification.
- Bench tested on actual hardware: We cycled this cell through charge and discharge on the SR-225 receiver board. The BMS accepted the cell without error flags, charge termination triggered correctly at full voltage, and stimulation output held consistent across test cycles.
- Collar reactivation after cell swap: After fitting the new battery, pair the receiver to the transmitter again before field use — the SR-225 loses its link state when power is fully interrupted, and the transmitter will not send stimulus to an unpaired collar.
Why the SR-225 receiver stops responding mid-session after a battery swap
The SR-225 receiver draws a brief current spike each time it executes a stimulation command. A degraded or deeply discharged cell sags below the BMS cutoff threshold during that spike, causing the receiver to shut off even if the resting voltage looks acceptable. A fresh 160mAh cell at full charge maintains voltage above the cutoff during these transient draws. If the collar shuts off during a command after fitting this battery, confirm the cell was charged fully before use — resting voltage should read at or above 4.1V on a multimeter before installation.
Transmitter showing "out of range" when collar is nearby
This symptom appears when the receiver collar has lost its paired state with the transmitter after a power interruption — it is not a range problem. When the SR-225 receiver loses battery power completely, the link registration clears from memory. The transmitter interprets an unpaired collar as out of range rather than unpaired. Re-run the pairing sequence from the transmitter according to the SR-225 manual, with collar and transmitter within one metre of each other, to restore the link.