About this replacement
Crestron SmarTouch 1550 / 1700 — 4.8V Ni-MH Replacement Battery (ST-BTPN)
This is a 4.8V, 3600mAh Ni-MH replacement battery for the Crestron SmarTouch 1550 and SmarTouch 1700 wireless touchscreen controllers. These controllers manage AV systems, lighting, and environmental controls in commercial and residential installations. OEM part number ST-BTPN.
- SmarTouch 1550 and 1700 platform fit: Both models share the same 4.8V battery rail, connector format, and ST-BTPN part number. The four-cell Ni-MH pack matches the BMS voltage thresholds Crestron programmed into both controllers — no reconfiguration needed after swap.
- Bench tested on actual hardware: We cycled this pack through charge and discharge on a Crestron SmarTouch unit and confirmed the BMS accepted the pack without error flags, held stable voltage under IR LED load bursts, and reported charge status correctly on the controller display.
- Ni-MH cell matching on multi-cell packs: This is a four-cell series pack. If any individual cell in the old pack has failed, the remaining cells may have been driven into reverse polarity. Install this replacement as a complete unit — never substitute a single cell into the existing housing, as mismatched cells accelerate capacity fade across the whole pack.
Why the SmarTouch 1550 drops IR range before the battery fully depletes
Ni-MH cells show a gradual voltage curve rather than a sudden cutoff. As the pack ages, terminal voltage sags under the brief high-current draw of each IR LED burst, even if the resting voltage still reads acceptable. The SmarTouch 1550's IR emitter needs a consistent voltage spike to drive the LED at full intensity — below that threshold, the signal weakens and the controller appears to lose range before the battery indicator warns you. Replacing the ST-BTPN pack restores full LED drive current from the first charge cycle.
SmarTouch 1700 shows "Charging" indefinitely after battery swap
Crestron's SmarTouch charging circuit uses a delta-V detection method to identify when a Ni-MH pack is full — it looks for a small voltage dip that signals full charge. A new pack at low state of charge may take longer to reach that dip point than the original depleted pack did, which can make the "Charging" indicator persist longer than expected. This is normal behaviour for a fresh Ni-MH pack on the first cycle. Let the controller complete the full charge uninterrupted — the indicator should clear once the pack reaches approximately 5.6V–5.8V under the charger.