Seiko DPU-3445 Replacement Battery 7.4V 2200mAh BP-3007-A1-E

Seiko DPU-3445 — 7.4V Li-ion Replacement Battery (BP-3007-A1-E)

This 7.4V, 2200mAh Li-ion battery replaces the BP-3007-A1-E pack in the Seiko DPU-3445 portable thermal printer. The DPU-3445 is a compact mobile printer used in retail point-of-sale, logistics, and field service applications. It slots into the original battery bay and connects to the same BMS handshake circuit as the factory unit.

• DPU-3445 platform fit: The DPU-3445 uses a 7.4V nominal rail to drive both the thermal print head and the paper feed motor from a single cell pack. This replacement matches that voltage profile exactly, keeping both subsystems within their operating window without triggering the printer's low-voltage protection cutoff.
• Bench tested on actual hardware: We ran this cell through the DPU-3445's BMS initialisation cycle and confirmed the protection circuit accepted the pack without fault codes. Discharge curves under simulated print-head load stayed flat through the mid-range before the expected taper toward cutoff.
• First-use print calibration: After installing, charge the pack fully, then print five consecutive test receipts before deploying. The paper feed motor draws a short current spike on each feed cycle — running through a calibration sequence confirms the BMS has set the correct current profile for the new cells.

Voltage sag on the DPU-3445 thermal head during multi-line print bursts

The DPU-3445 thermal head fires dot rows in rapid sequence during dense barcode or graphic label output. Each burst pulls a short high-current spike from the battery. A degraded or deeply discharged pack can't sustain that current without voltage sagging below the head's operating threshold. When that happens, the printer either skips dot rows or pauses mid-print while the protection circuit recovers. A fresh cell at full charge maintains the voltage rail above 7.0V during these bursts, keeping print output consistent.

Bluetooth connection dropping mid-job on the DPU-3445

The DPU-3445's Bluetooth radio shares the same 7.4V supply as the print engine. At low state of charge, the battery's internal resistance rises and voltage sags during print motor activity — that sag is enough to reset the radio module, dropping the wireless connection mid-job. The printer typically re-pairs automatically, but the job data is lost. Keeping the battery above 7.0V resting voltage before a print session prevents the sag from reaching the radio's reset threshold. Charge fully before any wireless-dependent deployment.