BTI Clarity 600 Replacement Battery 2.4V 1200mAh Ni-MH

BTI Clarity 600 / Synergy Series — 2.4V Ni-MH Replacement Battery

This is a 2.4V, 1200mAh Ni-MH replacement battery for the Clarity 600, Synergy 500, Synergy 600, and Synergy 700 cordless phone handsets. It slots directly into the handset battery compartment and restores talk time and standby performance lost when the original cell degrades. Voltage and physical footprint match the OEM pack at 50.25 × 28.09 × 14.41mm.

• Clarity 600 and Synergy 500/600/700 compatibility: These four handsets share the same 2.4V two-cell NiMH pack format, identical connector orientation, and the same charge-control circuit in the base station — so one battery fits all four without modification.
• Bench tested on actual hardware: We ran this pack through charge and discharge cycles on a Synergy 600 handset. The base station accepted the battery without fault indication, and the BMS held voltage within the handset's operating window throughout the discharge curve.
• First-charge protocol for NiMH cordless packs: After installing the new battery, place the handset in the base and leave it there for a full 16 hours before first use. NiMH cells at storage charge cannot reach rated 1200mAh capacity on a short charge — the slow trickle cycle is what brings them up to spec.

Talk time shorter than original battery after replacement

A fresh NiMH pack often delivers noticeably less talk time for the first three to five charge cycles. This is normal — NiMH cells ship in a partial state and need repeated full charge-discharge cycles to reach rated capacity. The chemistry forms properly only under load. Run the handset until it drops to low-battery indication, return it to the base for a full charge, and repeat for at least three cycles before judging performance.

Base station showing no charge or error light on new pack

NiMH batteries lose voltage during storage. If a new pack sits in a warehouse for several months, its resting voltage can drop below the threshold the base station uses to detect a valid battery — the charger sees a voltage it does not recognise and throws a fault. Remove the handset, leave it out for 30 seconds, then reseat it firmly so the charge contacts are clean and flush. If the error persists, the pack voltage may need a brief external boost charge to 2.4V before the base will accept it.