TakTark BM603 Baby Monitor Replacement Battery 3.7V 750mAh

TakTark BM603 — 3.7V Li-Polymer Replacement Battery

This is a 3.7V, 750mAh lithium-polymer battery for the TakTark BM603 baby monitor. It fits the parent unit of this two-way baby phone system. Dimensions are 37.20 × 32.70 × 5.20mm — verify your existing cell before ordering.

• BM603 parent unit fit: The BM603 parent unit runs on a single Li-Polymer cell at 3.7V nominal. This replacement matches that voltage rail and physical footprint. A mismatched cell voltage will trip the unit's protection circuit and prevent charging.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the BM603 platform. The BMS accepted the cell without fault codes, and charge termination triggered correctly at full capacity.
• Post-swap wireless re-pair: When the parent unit loses power completely during a battery swap, it drops its stored link to the camera unit. After fitting this battery, charge the parent unit first, then re-pair it with the camera unit using the sync button — the monitor will not connect automatically after a full power loss.

Parent unit battery draining overnight on the BM603

The BM603 parent unit draws sustained current overnight when the screen stays on during monitoring. A 750mAh cell running a backlit display, speaker, and radio receiver will deplete faster than most users expect. Enable the screen timeout setting so the display powers off between alerts. The radio receiver stays active in standby — only the screen draw drops, which is where most of the overnight drain comes from.

BM603 night vision not working after battery replacement

The infrared LEDs on the camera unit require a stable voltage supply to fire at full intensity — this is not a parent unit issue, but a flat parent unit battery can cause communication drops that look like a night vision fault. If the image is dark or grainy after a swap, the parent unit battery likely hasn't charged enough to maintain a clean radio link to the camera. Charge the parent unit to full before testing night vision. If the IR LEDs still don't activate, check the camera unit's night mode setting in the menu.