About this replacement
Autec DJM / FJM Series — 7.4V Li-Polymer Replacement Battery (LPM04)
This 7.4V, 5000mAh Li-Polymer battery replaces the original LPM04 cell in Autec DJM, DJR, FJM, and FJR wireless crane remote transmitters. It fits the handheld unit that operators use to control overhead cranes and lifting equipment from the floor. Voltage and capacity match the OEM spec exactly — 7.4V, 5000mAh (37Wh).
- DJM, DJR, FJM, FJR transmitter fit: These four Autec remote families share the same battery bay geometry, connector pinout, and BMS handshake protocol — all four accept the LPM04 cell on the same voltage rail without modification.
- Bench tested on actual hardware: We cycled this cell through full charge-discharge sequences on the DJM transmitter. The BMS responded correctly at both low-voltage cutoff and charge-complete thresholds — no false trips, no communication errors with the transmitter's onboard controller.
- Storage charge for infrequent crane operations: If the remote sits idle between jobs, charge this battery once a month. Li-Polymer cells that drop below 2.5V per cell can trigger BMS lockout — the charger connects but the battery will not respond.
Solenoid activation causing power dropout mid-operation
When a crane remote triggers a solenoid or contactor, the inrush current spike can exceed what a degraded or partially charged battery can sustain. The BMS interprets this as an over-current event and cuts output to protect the cells. This appears as the remote going dark or resetting exactly when a hoist or travel function is commanded. A fully charged 5000mAh cell at 7.4V handles this inrush load — a cell sitting at storage voltage of around 3.8V per cell often cannot.
Remote showing low-battery warning immediately after new cell install
Li-Polymer cells ship at storage voltage — typically 3.7–3.85V per cell, not full charge. The Autec transmitter reads this as low battery because its threshold is set above storage level. This is not a faulty cell. Connect the battery to the Autec charger and bring it to full charge before the first use. Once at 4.2V per cell, the low-battery indicator will clear.