Columbia CTA300 Cordless Phone Replacement Battery 3.6V 700mAh

Columbia CTA300 — 3.6V Ni-MH Replacement Battery

This is a 3.6V, 700mAh Ni-MH replacement battery for the Columbia CTA300 cordless phone handset. It slots directly into the handset battery compartment and restores power to a phone that no longer holds a charge. Dimensions are 45.60 x 31.30 x 10.60mm — measure your existing pack before ordering if unsure.

• CTA300 handset compatibility: The CTA300 runs on a single 3.6V Ni-MH cell pack. This battery matches that voltage rail and physical footprint, so the handset's charge circuit sees what it expects from the base station.
• Bench tested on actual hardware: We cycled this pack through charge and discharge on the bench. The cell voltage held within spec across the first five cycles, and the handset's charge indicator responded correctly throughout.
• First-charge protocol for Ni-MH cordless packs: After installing, seat the handset in the base and leave it for a full 16 hours before the first use. Ni-MH cells from storage need a slow initial charge to reach rated capacity — skipping this is the most common reason a new battery underperforms from day one.

Base station showing no charge or error light after battery swap

A fresh Ni-MH pack from storage sits at a lower resting voltage than a partially used original. Some cordless base stations read that low voltage as a fault and refuse to start the charge cycle. The fix is to seat the handset firmly in the base and leave it for 30–60 minutes — most bases will re-attempt the charge cycle once the pack voltage climbs slightly from the trickle current. If the error light persists past an hour, remove the handset, wait 10 seconds, and reseat it to trigger a fresh detection cycle.

Range drops noticeably when the new battery is under RF load

Ni-MH packs that haven't completed conditioning cycles show higher internal resistance than a broken-in cell. When the DECT transmitter draws current during a call, voltage sags more than normal — the handset's RF output drops to compensate, and range suffers. This is not a defective battery. Run three to five full charge and discharge cycles and internal resistance drops, voltage sag reduces, and transmit power stabilises. After the fifth cycle, check whether range has returned to what you'd expect from this handset.