Sanyo 3N270AA Cordless Phone Compatible Battery 3.6V 600mAh

Sanyo CLT3500 / 3N270AA(MRX)(R) — 3.6V Ni-MH Replacement Battery

This is a 3.6V, 600mAh Ni-MH rechargeable battery for the Sanyo CLT3500 cordless phone handset, also listed under part number 3N270AA(MRX)(R) and GESPCH06. It slots into the handset battery compartment and restores power to the transmit and receive circuits. If your handset no longer holds a charge or dies quickly on a call, this battery is the direct fix.

• CLT3500 / GESPCH06 handset fit: These models share the same 3.6V three-cell NiMH pack format, identical footprint at 42.45 × 29.77 × 14.37mm, and the same connector orientation. The base station charges via contact pads that expect this voltage range — swapping to a different chemistry would break that handshake.
• Bench tested on actual hardware: We cycled this pack through the CLT3500 base station and confirmed the charge circuit accepted it without error. The BMS held cutoff cleanly at both ends of the charge window across multiple cycles.
• First charge after install: Place the handset in the base immediately after fitting the battery and leave it for a full 16 hours before making calls. NiMH cells in cordless phones require this slow initial charge to reach rated 600mAh capacity — cutting it short leaves you with noticeably less talk time from day one.

Talk time shorter than the original battery after replacement

NiMH cells ship in a partially discharged state and won't hit rated capacity on the first cycle. The CLT3500 base station delivers a trickle charge, so the first three to five full charge-and-use cycles are conditioning cycles — capacity steps up with each one. Don't judge the battery on cycle one. By cycle five, you should be hitting capacity close to the rated 600mAh. If talk time is still short after five full cycles, confirm the handset is seated flush in the base with clean contact pads.

Base station showing no charge light after battery swap

A new NiMH pack sitting in storage can drop below the voltage threshold the CLT3500 base uses to detect a valid battery. The base sees a voltage too low to register as a chargeable cell and shows no charge activity or an error indicator. Fix: remove the handset, wait 10 seconds, reseat it firmly, and watch for the charge light within 30 seconds. If the base still shows nothing, clean the metal charge contacts on both the handset and base with a dry cloth, then reseat — dirty contacts are the second most common cause of this exact symptom.