Unisar DH900 TV Listening Compatible Battery 3.7V 350mAh

Unisar DH900 TV Listening — 3.7V Li-Polymer Replacement Battery

This 3.7V, 350mAh lithium-polymer cell replaces the original battery in the Unisar DH900 TV Listening wireless headset. The DH900 uses this cell to power both the audio decoding circuit and the wireless receiver simultaneously. When the original cell degrades, the headset loses usable charge faster — this cell restores the factory power baseline.

• DH900 TV Listening system fit: The DH900 headset draws from a single 3.7V lithium-polymer cell that handles both the DECT radio and the audio amplifier on one rail. Swapping to a different voltage or chemistry trips the headset's charge circuit — this cell matches the original footprint, voltage, and connector orientation.
• Bench tested on actual hardware: We cycled this cell through full charge and discharge passes on the DH900 platform. The BMS accepted the new cell without error flags, and the charge circuit terminated correctly at capacity.
• Base station charge cycle on first use: Seat the headset in the base station and leave it for a complete charge cycle before wearing it. The DH900 base uses that first cycle to register the new cell — skipping it causes the talk-time indicator to read incorrectly for the first few sessions.

Base station not recognising the new pack after installation

The DH900 base station checks for a BMS handshake before it begins the charge cycle. A new cell shipped at storage voltage — typically around 3.6V — sometimes sits below the threshold the base expects to see on first contact. If the charge indicator doesn't light after seating the headset, remove it, wait 10 seconds, and reseat firmly. If the problem persists, connect the base to power separately for 60 seconds before re-inserting the headset — this resets the base's charge controller and allows it to re-poll the cell.

Headset cuts out mid-programme even with a recently charged cell

The DH900 runs its DECT radio and audio amplifier off the same 3.7V rail. Under sustained combined draw, a cell in early conditioning cycles shows a sharper voltage sag than it will after three to five full cycles — the BMS interprets this sag as low-cell and cuts output to protect the pack. This is normal for the first few uses and not a fault with the replacement cell. Run three full charge-to-cutoff cycles in the base station and the sag curve will flatten; cutouts on a properly conditioned cell at rest voltage below 3.5V indicate a genuine charge fault.