Samsung ER-290 Cash Register Replacement Battery 3.6V 80mAh

Samsung Sam4s ER-290 / ER-350 Series — 3.6V Ni-MH Replacement Battery (3N65BC)

This is a 3.6V, 80mAh Ni-MH backup battery for Samsung Sam4s cash registers including the ER-290, ER-350, and ER-350II series. It fits directly into the backup battery socket and maintains RAM-stored data — programmed prices, tax rates, and totals — when mains power is lost or the register is unplugged. OEM part numbers covered include 3N65BC, 60BNK3A2H, 60BVK3A2H, and 80BVH3A2H.

• ER-290 / ER-350 platform fit: These models share the same backup circuit board layout and trickle-charge voltage rail. The connector, cell count, and BMS tolerances are identical across the range, which is why one cell covers all listed variants.
• Bench tested on actual hardware: We ran this cell through the Sam4s trickle-charge circuit and confirmed the BMS accepts charge within expected parameters. Charge acceptance and discharge cutoff both sat within spec for a 3.6V Ni-MH backup cell of this size.
• Post-install charge protocol for Sam4s registers: After fitting this battery, leave the register running on mains power for a minimum of 12 hours before testing backup function. The Sam4s trickle-charge circuit is slow by design — skipping this step means the cell will not hold the RAM through even a short outage.

Why the Sam4s ER-350 loses programmed prices after every power outage

The ER-350 stores PLU prices, tax tables, and department totals in volatile RAM. That RAM needs a continuous low-level supply from the backup battery the moment mains drops. When the backup cell is depleted or degraded, the RAM loses power in seconds and resets to factory defaults. A new cell alone does not fix this — the cell must be fully charged through the register's internal trickle charger first. If prices keep disappearing after fitting a fresh battery, the cell was not given sufficient charge time before the outage occurred.

Register display goes blank when mains power fails

An 80mAh backup cell at 3.6V carries roughly 0.29Wh of usable energy — enough to sustain RAM retention, but not enough to drive the display and printer simultaneously. If the display goes blank the moment mains fails, the backup battery is not the fault — the cell is doing its job protecting memory, and the display load is simply beyond its capacity. Check whether programmed data survived the outage; if prices and totals are intact, the battery is working correctly. If data is also lost, the cell needs a full 12-hour charge cycle on mains before the next power interruption.