Trimble KLN00928 SPS855 Replacement Battery 7.4V 8000mAh

Trimble SPS855 / SPS850 Series — 7.4V Li-Polymer Replacement Battery (KLN00928)

This is a 7.4V 8000mAh (59.2Wh) Li-Polymer replacement for the KLN00928 battery pack. It fits the Trimble SPS850, SPS851, SPS852, and SPS855 Modular Receivers — professional GNSS units used on construction and survey sites. The cell dimensions match the original at 120.00 × 101.50 × 9.80mm, so the pack seats correctly in the battery compartment without modification.

• SPS850–SPS855 platform compatibility: These four receivers share the same battery bay geometry, voltage rail, and BMS handshake protocol. The KLN00928 form factor is consistent across the series, so one replacement pack covers all four model variants without adaptation.
• Bench tested on actual hardware: We cycled this pack through receiver power-on, satellite acquisition, and sustained GNSS logging. The BMS held stable under the combined RF module and data-logging draw, and cell voltage stayed within the receiver's acceptable operating window throughout.
• Post-install calibration on the SPS series: After fitting a new pack, run a full calibration cycle through the receiver's instrument menu before field deployment. The SPS firmware maps battery state during that sequence — skipping it causes the low-battery indicator to trigger prematurely on the first session, even with a full charge.

BMS lockout after the SPS855 sat unused in a carry case for months

Li-Polymer cells self-discharge slowly during storage. If a pack sits long enough, cell voltage drops below the BMS protection threshold — typically around 2.5V per cell — and the BMS latches into lockout mode to prevent damage. In this state the receiver sees no pack at all, and standard charging attempts do nothing. The fix is a controlled low-current pre-charge using a charger that supports recovery mode, bringing each cell back above the 2.8V re-enable threshold before the BMS will accept a normal charge cycle.

SPS receiver shuts down mid-session during USB data transfer to the office laptop

USB data transfer from the SPS series adds a second draw on top of the active GNSS engine — the combined load can push current demand beyond what an aged or partially discharged cell can sustain. When cell voltage sags under that combined draw, the BMS trips the output to protect the cells and the receiver cuts off instantly. This is not a firmware fault. Charge the pack fully before any transfer session, and check that the receiver's USB port is not also acting as a charging source for another device at the same time.