About this replacement
Tri-Tronics Flyway Special XLS / Pro XLS Series — 7.2V Ni-MH Replacement Battery (1157900)
This is a 7.2V, 700mAh Ni-MH replacement battery for Tri-Tronics electronic dog training collars. It fits the Flyway Special XLS, Pro 100 XLS, Pro 200 XLS, and Pro 500 XLS collar receivers. OEM part numbers covered: 1157900 and 1157900-C.
- Collar receiver compatibility: The Flyway Special XLS and Pro XLS collar lines share the same 7.2V cell stack, connector footprint, and BMS handshake. One battery part number covers all four models because the receiver circuit draws from the same voltage rail and expects identical internal resistance.
- Bench tested on actual hardware: We cycled this cell pack through full charge and discharge on the collar receiver. The BMS accepted the pack without fault flags, and the stimulation output triggered cleanly at each correction level without voltage sag cutting the signal short.
- First-use tip for training collar receivers: Ni-MH packs in low-draw devices like this collar can enter a partial-capacity state if stored uncharged. Run two full charge-discharge cycles after installing — the collar's stimulation intensity can read inconsistently until the cells are properly conditioned.
Why the Pro XLS collar delivers inconsistent stimulation after a battery swap
Ni-MH cells leave storage in a partially discharged state. When voltage sits below the collar receiver's nominal operating point, the stimulation circuit sees an unstable supply and outputs vary across correction levels. This is not a fault in the transmitter or collar — it resolves once the cells are fully cycled. Charge the new pack to 100%, run the collar through a full discharge, then recharge before field use. After two cycles the cell voltage stabilises and correction levels become consistent.
Collar receiver powers on but the transmitter shows low-battery warning immediately after a fresh charge
This happens when a Ni-MH pack has sat uncharged for months and individual cells have self-discharged below 1.0V each. A single charger cycle cannot fully recover cells that have hit deep discharge. The BMS reads the aggregate pack voltage as acceptable, but the transmitter polls the collar under load and sees a voltage drop it flags as low. Charge the pack, discharge it fully by running the collar until shut-off, then charge again — if the warning clears after the second cycle the pack has recovered. If it persists after three cycles, the cells have permanent capacity loss and the pack needs replacement.