Energy Plus SL35 10.8V Lithium-Ion Replacement Battery 5200mAh

Energy Plus SL35 / Plus SMP35 — 10.8V Li-ion Replacement Battery

This is a 10.8V 5200mAh (56.16Wh) Li-ion battery for the Energy Plus SL35 and Plus SMP35 laser distance meters. Both instruments use the same battery format, connector, and BMS handshake, so one part number covers both. Capacity figure comes from the product data, not the original pack label.

• Plus SL35 and SMP35 compatibility: Both models run the same 10.8V power rail and share an identical connector housing and BMS communication protocol. The SMP35 adds a second measurement mode but draws from the same voltage plane — no electrical difference at the battery interface.
• Bench tested on actual hardware: We cycled this pack through the SL35 instrument under continuous laser and display load. The BMS held the 10.8V rail steady through repeated measurement bursts and flagged low-cell correctly at the instrument's shutdown threshold without false cutoffs.
• First-use calibration on the SL35: After installing this pack, run a full calibration cycle through the instrument menu before field deployment. The SL35 maps battery state during that routine — skipping it causes premature low-battery warnings during your first measurement session even when the pack is near full charge.

BMS cutoff when the SL35 initialises its laser module at power-on

The SL35 fires a short current spike when it powers up the laser and sensor array. On a depleted or deeply discharged pack, that spike can push the instantaneous draw past the BMS overcurrent threshold, causing an immediate shutdown before the display fully loads. This is not a fault in the instrument — it is the BMS protecting cells that are below safe delivery voltage. Charge the replacement pack to full before the first power-on, and the spike will fall within normal operating range.

Readings resetting or display rebooting mid-logging session

During a sustained logging session, the SL35 pulls continuous current for the laser, processor, and display simultaneously. If cell voltage sags under that combined load — typically below 9.0V across the 3S arrangement — the instrument treats it as a power interruption and resets the active measurement log. This is a voltage dropout event, not a firmware issue. Confirm the pack reads at least 11.0V on a multimeter before starting a long session, and replace the pack if resting voltage drops below 10.5V between uses.