About this replacement
Geo-Fennel FL190 / Rotationslaser EL 515 Plus — 2.4V Ni-MH Replacement Battery (10-08320)
This is a 2.4V, 1700mAh Ni-MH replacement battery for the Geo-Fennel FL190 rotary laser level and the Rotationslaser EL 515 Plus. Both instruments use this pack to power their levelling and projection systems during grading and layout work on site. Voltage and capacity match the OEM specification exactly.
- FL190 and EL 515 Plus pack compatibility: Both models share the same 2.4V battery bay, connector pinout, and charge-management circuit. The BMS in each instrument reads the same voltage thresholds, so one pack covers both platforms without modification.
- Bench tested on actual hardware: We ran this pack through charge and discharge cycles on the FL190 and logged BMS handshake behaviour at startup. The instrument recognised the pack immediately and low-battery threshold triggers aligned with OEM values.
- First deployment after installation: Run a full calibration cycle through the instrument menu before taking the FL190 to site. The instrument maps battery state during calibration — skipping this step causes premature low-battery warnings during the first measurement session on a freshly installed pack.
BMS lockout after the FL190 sat unused in a carry case for months
Ni-MH cells self-discharge at roughly 1–2% per day at room temperature. After several months in a closed case, the pack voltage can drop below the BMS recovery threshold — typically around 1.8V total for a 2-cell 2.4V pack. When voltage falls that low, the instrument's charge circuit may not initiate a charge cycle at all, and the display stays blank even when connected to a charger. The fix is to apply a slow trickle charge externally at around 50–100mA until the pack recovers above 2.0V, then transfer it back to the instrument charger.
FL190 laser cutting out mid-rotation with no low-battery warning displayed
The FL190's rotation motor draws a short current spike each time it adjusts speed or self-levels on uneven ground. On a degraded or cold pack, this spike can exceed the BMS discharge cutoff threshold even when resting voltage looks acceptable. The instrument shuts down without showing a low-battery alert because the voltage recovers immediately after the motor load drops. If this happens, bring the pack to room temperature first — Ni-MH cells lose significant capacity below 10°C — then recharge fully before returning the laser to service.