About this replacement
Seiko DPU-3445 — 7.4V Li-ion Replacement Battery (BP-3007-A1-E)
This 7.4V, 3400mAh Li-ion battery replaces the OEM BP-3007-A1-E pack in the Seiko DPU-3445 portable thermal printer. The DPU-3445 is a compact mobile unit used in retail, logistics, and hospitality for on-the-spot receipt and label printing. Capacity is sourced from product data at 25.16Wh — matching the original cell spec.
- DPU-3445 platform fit: The DPU-3445 runs a 7.4V nominal rail shared across its paper feed motor, thermal print head, and wireless radio. The BP-3007-A1-E form factor locks into the battery bay with a keyed connector and a BMS handshake that the printer firmware checks on boot — a mismatched cell pack will fail that handshake and prevent operation.
- Bench tested on actual hardware: We ran this cell through charge cycles on the DPU-3445 and monitored BMS communication at startup. The pack cleared the firmware handshake, held voltage steady across simultaneous motor drive and thermal head activation, and tripped protective cutoff correctly at the low-cell threshold.
- First-use print sequence: After installing, charge the pack fully, then print five test receipts before field deployment. The paper feed motor draws a brief inrush current on each feed cycle — running that sequence lets the BMS log the load profile and confirm the current delivery curve is correctly calibrated for the new cell.
Bluetooth dropping mid-print job on the DPU-3445
The DPU-3445 runs its Bluetooth radio and print head from the same 7.4V rail. When the cell is partially depleted, a simultaneous motor inrush and thermal head activation can pull voltage low enough that the radio loses power momentarily — the host device reads this as a disconnection. A degraded or deeply discharged OEM pack will trigger this even at 60–70% displayed charge. Replacing the cell and ensuring it is charged above 7.2V before starting a multi-page job eliminates the drop.
Faded or uneven print density on the first few receipts
The thermal print head in the DPU-3445 requires stable voltage to hold consistent head temperature across the full print width. If the battery voltage sags during a print pass — common with aged or freshly installed cells that haven't settled — the head temperature drops mid-line, producing faded or banded output. This is not a head fault. Run the five-receipt calibration sequence after a full charge and the voltage delivery stabilises. If banding persists beyond that, check that cell voltage at rest reads at least 7.4V before printing.