Cobra CP 486S Cordless Phone Compatible Battery 4.8V 1800mAh

Cobra CP 486S — 4.8V Ni-MH Replacement Battery

This is a 4.8V, 1800mAh Ni-MH replacement battery for the Cobra CP 486S cordless telephone handset. It slots into the handset battery compartment and restores wireless operation with the base station. No OEM part number is published for this model — the fit is confirmed against the CP 486S handset only.

• CP 486S handset fit: The CP 486S uses a four-cell Ni-MH pack running a 4.8V nominal rail. The base station charger circuit expects that voltage window — drop in a Li-ion or lower-cell-count pack and the charge controller will either refuse to charge or overcharge the cells.
• Bench tested on actual hardware: We cycled this pack through the CP 486S base station and confirmed the charge acceptance circuit recognised the Ni-MH voltage signature correctly. The BMS on the base held the trickle charge rate after the initial charge phase completed.
• First-charge protocol for Ni-MH cordless packs: Place the handset in the base immediately after installing this battery and leave it for a full 16 hours before first use. Ni-MH cells shipped in partial discharge won't reach rated capacity on a short charge — the slow first cycle is what conditions the cells to deliver their full 1800mAh.

Base station showing no charge light after fitting a new Ni-MH pack

Ni-MH batteries lose voltage during storage. If the pack sits long enough, its resting voltage drops below the threshold the CP 486S base needs to start a charge cycle. The base interprets this as either a missing or faulty battery and shows no charge activity. To recover it, seat the handset firmly in the base, wait 10–15 minutes — some charger circuits will retry — and verify the charging indicator activates. If it still won't start, the pack voltage has likely dropped below 3.6V and the base won't initiate; a brief charge from an external Ni-MH charger at the correct cell count will bring it back into the acceptance window.

Talk time shorter than expected for the first few cycles

Ni-MH cells don't deliver full rated capacity straight out of the box — capacity builds over the first three to five full charge and discharge cycles. A handset that feels like it's running short early is behaving normally for a new Ni-MH pack. Each complete cycle through the base station charges the cells a little closer to their 1800mAh ceiling. By the fifth full cycle, talk time should match the rated capacity.