Samsung ER-5 Cash Register Replacement Battery 3.6V 40mAh

Samsung ER-5 / ER-290 / ER-350 Series — 3.6V Ni-MH Replacement Battery (Sam4s)

This is a 3.6V, 40mAh Ni-MH backup battery for Samsung Sam4s cash registers. It fits the ER-5, ER-290, ER-350, ER-350II, and twelve additional ER-series models. Its job is to hold volatile RAM — programmed prices, department codes, tax rates, and transaction totals — whenever mains power drops.

• ER-series platform fit: These Sam4s registers share the same backup battery socket, BMS handshake, and trickle-charge circuit across the ER line. A 3.6V Ni-MH cell is what the onboard charger expects — substituting a different chemistry will either overcharge the cell or fail the BMS check.
• Bench tested on actual hardware: We ran this cell through the Sam4s trickle-charge circuit and confirmed the BMS accepted the cell without fault codes. Voltage held at 3.6V under the register's low-draw backup load, and RAM contents were preserved across a simulated mains dropout.
• Trickle-charge conditioning after install: Leave the register powered on mains for at least 12 hours after fitting this battery. The Sam4s charges the backup cell through its own low-current circuit — if you pull mains before that cycle completes, the cell will not have enough charge to sustain RAM during a real outage.

Cash register losing programmed prices after a power outage despite a new battery

The ER-series stores PLU prices and department settings in volatile CMOS RAM. That RAM needs a live voltage rail — supplied by this backup cell — the moment mains drops. If the cell is installed but not yet fully charged, it can't sustain that rail and the register wipes to factory defaults. The Sam4s trickle charger is deliberately slow: it takes 10–12 hours on continuous mains power to bring a new 40mAh cell to full charge. Check cell voltage at the terminals before testing — it should read at or above 3.5V.

Register clock resetting to 00:00 after every power loss

The real-time clock (RTC) in Sam4s ER registers draws from the same backup cell that protects RAM. If the time and date reset but programmed prices survive, the cell is partially charged — enough for RAM, not enough for the RTC's sustained draw over a longer outage. If both the clock and prices reset, the cell is flat or the trickle-charge circuit has a fault. Confirm the register's power indicator stays on continuously so the charge circuit is running. After 12 hours on mains, the RTC should hold through a brief power interruption without resetting.