AEMC 2118.57 Power Quality Analyzer Replacement Battery 12V 3000mAh

AEMC 8500 / DTR-8500 — 12V Ni-MH Replacement Battery (2118.57)

This is a 12V 3000mAh (36Wh) Ni-MH replacement for the AEMC 8500 and DTR-8500 power quality analyzer and Digital Transformer Ratiometer. It uses OEM part number 2118.57 and fits the battery bay on all three variants listed above. Voltage and capacity match the original pack specification exactly.

• 8500, DTR-8500, and Digital Transformer Ratiometer 8500 compatibility: All three variants share the same 12V battery architecture, connector pinout, and BMS handshake protocol. One pack covers the full platform — no adapter or firmware difference between them.
• Bench tested on actual hardware: We cycled this pack through the 8500's instrument boot sequence, probe initialisation, and sustained logging load. The BMS handled the probe power-up current spike without tripping, and cell voltage held stable under continuous sensor draw across the full measurement session.
• Post-install calibration before field deployment: After fitting this pack, run a full calibration cycle through the instrument menu before your first site survey. The 8500 maps battery state during calibration — skip this and the instrument will throw premature low-battery warnings on the first measurement session even with a full charge.

BMS lockout after the DTR-8500 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 9V for a 12V Ni-MH pack — and the protection circuit latches off. The instrument sees no pack at all, not a flat one. To recover, connect the battery to its charger for at least 15–20 minutes before attempting to power on the instrument; most BMS circuits require a trickle-charge pulse to exit sleep mode and re-enable output. If the charger shows no activity after 30 minutes, the pack has dropped below recoverable voltage and needs replacement.

8500 shuts down mid-logging session despite showing adequate charge

This is a voltage sag issue, not a capacity issue. Under sustained sensor and logging load, degraded Ni-MH cells drop internal resistance rises sharply, pulling cell voltage below the instrument's cutoff threshold even though resting voltage looks acceptable. The 8500 shuts down to protect its measurement circuitry rather than log corrupted data. Check resting voltage after a shutdown — if it recovers above 12V within two minutes, the cells have high internal resistance and the pack needs replacing. A healthy pack holds above 11.5V under load throughout a full survey session.