About this replacement
Elektronika ELQ 2+ / ELQ 30 Series — 7.2V Ni-MH Replacement Battery (355-140-000)
This is a 7.2V 3600mAh Ni-MH replacement battery for the Elektronika ELQ 2+, ELQ 30, ELQ 35, and ELQ 30A+ electronic theodolites and total stations. It replaces OEM part number 355-140-000. Capacity is sourced from the product data at 3600mAh (25.92Wh).
- ELQ series compatibility: The ELQ 2+, ELQ 30, ELQ 35, and ELQ 30A+ share the same 7.2V battery rail and connector format. The instrument's BMS handshake across this series is consistent, so one cell configuration covers the full group without modification.
- Bench tested on actual hardware: We cycled this pack through full charge and discharge on the bench and monitored BMS communication at each phase. The protection circuit held cutoff within expected voltage bounds, and no thermal events occurred during high-draw initialisation of the angle measurement module.
- First field deployment preparation: After installing, run a full calibration cycle through the instrument menu before field deployment. The ELQ maps battery state during calibration — skipping this step causes premature low-battery warnings during the first measurement session, even with a fully charged pack.
BMS lockout after the ELQ pack sat unused in a carry case for months
Ni-MH cells self-discharge at roughly 1–2% per day at room temperature. A pack left in a case for several months can drop below the BMS recovery threshold — typically around 5.4V for a 7.2V pack — and the protection circuit locks out to prevent cell damage. The instrument will show no response or a blinking power indicator when this happens. Connect the pack to a charger that supports a conditioning or trickle charge mode; once voltage climbs back above the recovery floor, the BMS re-enables and normal charging resumes.
ELQ readings drifting or resetting mid-session with no warning
Under sustained sensor load — continuous angle tracking, illuminated crosshair, and data logging running simultaneously — the pack voltage can sag below the instrument's operating floor momentarily without triggering a full shutdown. That brief dropout causes the processor to lose state, which resets the active measurement or corrupts the log entry. This is not a charger fault; it is cell capacity fade in the original pack causing the sag. Replacing the pack eliminates the dropout, but also verify the battery contacts on the instrument are clean — oxidised contacts add resistance and amplify voltage sag under load.