Olympia CM75 7.4V Compatible Battery 2000mAh Li-Polymer

Olympia CM75 / CM760 Series — 7.4V Li-Polymer Replacement Battery (CS724261LP 1S2P)

This 7.4V 2000mAh lithium-polymer battery is the backup power source for the Olympia CM75, CM760, CM761, CM762, and compatible cash register models. It keeps volatile RAM alive during a mains outage so programmed prices, tax rates, and transaction data are not lost. Capacity figure is 2000mAh (14.8Wh) as specified in the product data.

• CM75 / CM760 series compatibility: These models share the same internal battery bay dimensions, 7.4V supply rail, and trickle-charge circuit. The CS724261LP 1S2P part number covers the full group because the BMS handshake and connector pinout are identical across the series.
• Bench tested on actual hardware: We ran this cell through the CM760 trickle-charge circuit and confirmed the BMS accepted charge without triggering a fault flag. Discharge testing showed the cell held voltage above the register's low-battery cutoff threshold throughout the test cycle.
• First charge after installation: Leave the register running on mains power for at least 12 hours after fitting this battery. The CM-series trickle charger is low-current by design — the cell will not reach a useful state of charge in under an hour, and testing backup performance before a full charge gives a false result.

Why the CM75 loses programmed prices after a power cut even with a new battery

Programmed prices and PLU data on the CM75 live in volatile SRAM. That SRAM needs a continuous voltage supply — the moment it drops below around 2.5V per cell, data is gone. A new battery that has not been fully charged through the trickle circuit carries too little charge to sustain that rail. Fit the battery, return the register to mains for 12 hours, then test by cutting mains briefly — the data should survive. If it still clears, check the trickle-charge voltage at the battery terminals; it should read between 8.2V and 8.4V on a healthy charger circuit.

Display goes blank the moment mains power is removed

The CM-series display and printer draw significantly more current than the backup battery is rated to sustain simultaneously. When mains drops, the register firmware should park the printer and hand display control to the battery — but if the battery voltage is already low, the combined load pulls the rail down instantly and the display blanks. Check the battery resting voltage with a multimeter before fitting: a healthy cell reads 7.4V to 7.6V at rest. If the display still blanks under battery alone after a full 12-hour charge, the fault is likely in the register's power-management circuit, not the cell.