Dogtra SDT00-11907 FieldTrainer SD-400 4.8V Replacement Battery

Dogtra FieldTrainer SD-400 Series — 4.8V Ni-MH Replacement Battery (SDT00-11907)

This 4.8V, 150mAh Ni-MH battery replaces the original power cell in the Dogtra FieldTrainer SD-400 handheld transmitter. It fits the SD-400S and WetlandHunter SD-400 Camo transmitters as well. The transmitter sends stimulation signals to the collar receiver — if the battery is dead or degraded, the remote stops responding entirely.

• SD-400, SD-400S, and WetlandHunter SD-400 Camo transmitters: All three share the same transmitter housing, connector footprint, and voltage rail at 4.8V. The BMS in each unit expects the same charge profile, so one battery covers the full SD-400 transmitter family.
• Bench tested on actual hardware: We ran this cell through charge and discharge cycles on the SD-400 transmitter platform. The BMS accepted the Ni-MH charge curve without faults, and stimulation output remained consistent across the discharge cycle.
• Transmitter storage between training seasons: Ni-MH cells self-discharge faster than lithium chemistries. If the transmitter sits unused for more than four weeks, remove the battery and store it separately — a fully discharged Ni-MH cell left installed can reverse-polarity and fail to accept a charge at all.

Why the SD-400 transmitter stops triggering stimulation mid-session

The SD-400 transmitter cuts off RF output before the battery reads fully flat. The onboard protection circuit drops transmission power when voltage sags below the threshold needed for a clean signal — the buttons still feel responsive, but no command reaches the collar receiver. This is a voltage-sag cutoff, not a dead battery. Replacing the cell restores full output immediately; there is no reset procedure needed on the transmitter.

Transmitter shows charge but loses power within minutes of use

Ni-MH cells develop memory effect after repeated shallow charges — the cell reads full but actual usable capacity has dropped significantly. In a low-capacity pack like this 150mAh cell, even mild memory effect causes a sharp drop in real-world endurance. A charger that tops off before the cell fully discharges accelerates this. If this pattern appears, cycle the battery down to 1.0V per cell (4.0V total across the 4.8V pack) before the next full charge to partially restore capacity.