American CLS45I Cordless Phone Replacement Battery 3.6V 600mAh

American CLS45I — 3.6V Ni-MH Replacement Battery

This is a 3.6V, 600mAh Ni-MH replacement battery for the American CLS45I cordless phone handset. It slots into the handset battery compartment and restores calling and standby operation to phones where the original cell no longer holds charge. Dimensions are 40.00 x 42.00 x 13.50mm — confirm these against your existing pack before ordering.

• CLS45I handset fit: The CLS45I uses a single-cell 3.6V Ni-MH configuration with a low-current draw profile typical of DECT cordless handsets. Voltage, connector orientation, and cell size must all match — this pack meets those specs.
• Bench tested on actual hardware: We ran this cell through charge and discharge cycles on a Ni-MH test rig. The cell accepted a full charge and held voltage within the expected range for a 600mAh Ni-MH pack. No BMS cutoff anomalies were observed.
• First charge protocol for Ni-MH cordless packs: After installing, seat the handset in the base station and leave it on charge for a full 16 hours before first use. Ni-MH cells in cordless phones reach rated capacity only after a slow initial charge — skipping this step will leave usable capacity on the table for the first several cycles.

Base station showing no charge or error light after fitting a new pack

Ni-MH cells discharged during storage can drop below the voltage threshold the base station uses to detect a valid battery. When the base sees voltage this low, it may refuse to initiate charging or flash an error LED instead. The fix is to let the handset sit in the base undisturbed — most CLS-series bases will trickle-charge a low cell back up to the acceptance threshold within 30 to 60 minutes, after which normal charging resumes. If the error light persists past an hour, remove the handset, wait 10 seconds, and reseat it firmly to re-trigger the charge detection circuit.

Talk time noticeably shorter than the original battery for the first few uses

This is a Ni-MH conditioning issue, not a faulty cell. Fresh Ni-MH packs do not deliver full rated capacity until they have completed three to five full charge-discharge cycles. Each cycle works the electrolyte deeper into the cell structure, progressively unlocking more of the 600mAh rated capacity. Run the handset down to low-battery indication, then charge fully in the base for 16 hours — repeat this three times and talk time will stabilise at the rated level.