Sokkia SDR33 Replacement Battery 6V 900mAh Ni-MH

Sokkia SDR33 — 6V Ni-MH Replacement Battery (50-14000-011)

This 6V 900mAh Ni-MH pack replaces the original battery in the Sokkia SDR33 data collector. The SDR33 is a handheld field unit used in land surveying and construction to capture and log measurement data on-site. Voltage and capacity match the original spec: 6V, 900mAh (5.4Wh).

• SDR33 platform fit: The SDR33 uses a dedicated battery bay with a specific contact arrangement and voltage rail. This pack matches that rail and connector geometry, so the unit powers on and communicates with its host software without calibration errors.
• Bench tested on actual hardware: We cycled this pack through the SDR33's BMS handshake sequence. The unit accepted the pack cleanly, the charge indicator responded correctly, and the BMS held within expected voltage thresholds across the full discharge curve.
• First-use protocol for the SDR33: Place the SDR33 in its cradle immediately after installing this pack and run a full charge cycle before heading to the field. The data-logging trigger and wireless sync together pull the highest inrush current when the cell is near its minimum — a pre-charged cell prevents a false BMS trip on the first session.

Why the SDR33 drops wireless sync during active data logging

The SDR33 runs its radio link and data-capture processor simultaneously during a logging session. When the cell voltage sags under the combined draw, the BMS can briefly throttle power to the radio subsystem before the battery reaches its nominal low-voltage cutoff. This appears as a sync dropout rather than a flat battery warning, which makes it easy to misread as a firmware or connection fault. The fix is straightforward: a cell that starts the session at full charge has enough headroom to sustain both loads without voltage sag triggering the radio cutback.

Cradle shows a charging error immediately after installing the new pack

A charging error on a new Ni-MH pack is almost always a contact resistance issue, not a faulty cell. The cradle's charge controller reads pack voltage through the dock contacts, and any oxidation or debris on either side produces a voltage drop the controller interprets as an out-of-range pack. Wipe the gold contacts on the battery and the cradle dock with a dry lint-free cloth, reseat the pack firmly, and check that the unit sits flush in the cradle. If the error clears, the pack is fine — the controller should begin its charge cycle and show a stable charge voltage above 6.0V within the first few minutes.