NTi Audio Exel XL2 3.7V Replacement Battery 1800mAh

NTi Audio Exel XL2 — 3.7V Li-Polymer Replacement Battery (600 000 337)

This 3.7V 1800mAh Li-Polymer battery replaces the internal pack in the NTi Audio Exel XL2 sound level meter and acoustic analyser. It fits the XL2 and XL2 Analyzer variants. OEM part numbers 600 000 337 and LIP-009 both reference this cell.

• XL2 platform fit: The XL2 and XL2 Analyzer share the same battery bay, connector, and BMS handshake protocol. One pack covers both variants — no firmware or hardware differences affect compatibility across this model line.
• Bench tested on actual hardware: We cycled this pack through the XL2's charge and discharge routine on the bench. The BMS held the charge curve correctly, and the protection circuit responded cleanly to both end-of-charge and low-voltage cutoff thresholds.
• Pre-deployment calibration step: After fitting this pack, run a full calibration cycle through the XL2 instrument menu before taking it into the field. The instrument maps battery state during this process — skipping it causes the low-battery indicator to trigger early on the first measurement session, even with a full charge.

BMS lockout after the XL2 sat unused in a carry case for months

Li-Polymer cells self-discharge slowly during storage. If the XL2 sat unused for several months, the pack voltage may have dropped below the BMS recovery threshold — typically around 2.5V per cell. At that point, the protection circuit locks out charge current as a safety measure. Standard chargers will not wake the pack. Applying a low-current pre-charge through the XL2's USB-C port for 15–20 minutes is often enough to bring the cell back above the recovery threshold and allow normal charging to resume.

XL2 shuts down mid-measurement with no prior low-battery warning

This is a voltage dropout issue, not a capacity issue. Under sustained sensor load — particularly when the XL2 is running octave-band analysis or writing continuously to the SD card — current draw spikes enough to pull cell voltage below the BMS cutoff threshold momentarily. An aged or partially discharged cell has higher internal resistance, which makes the sag sharper. The fix is to ensure the pack is charged to at least 4.1V before a long logging session, and to check that the USB data connection is not active simultaneously, as combined draw accelerates the dropout.