Radio Shack 23-9091 Cordless Phone Replacement Battery 2.4V 1200mAh

Radio Shack 23-9091 / 960-2038 / 43-1099 — 2.4V Ni-MH Replacement Battery

This is a 2.4V, 1200mAh Ni-MH replacement battery for Radio Shack cordless phone handsets across three model numbers: 23-9091, 960-2038, and 43-1099. It slots directly into the handset battery compartment and connects to the same two-pin contact as the original pack. Capacity figures come from the product data — 1200mAh at 2.4V, 2.88Wh total.

• Three-model fit — 23-9091, 960-2038, 43-1099: These handsets share the same 2.4V Ni-MH cell format, connector pitch, and BMS handshake with the base station. One battery covers all three because the charging circuit expects the same voltage window and charge-acceptance curve.
• Bench tested on actual hardware: We cycled this pack through charge and discharge on a 2.4V Ni-MH test rig. The BMS accepted charge without error flags, and the pack held voltage within the expected window across multiple cycles without thermal events.
• First charge after installation: Place the handset in the base cradle for a full 16 hours before making any calls. Ni-MH cells in cordless phone packs ship partially discharged. Skipping this slow initial charge leaves capacity on the table for the first several cycles — not a fault, just chemistry.

Base station showing a charging error on a new Ni-MH pack

Radio Shack base stations use a delta-V detection method to confirm a battery is accepting charge. A new Ni-MH pack that has sat in storage for months may arrive at a voltage low enough that the base station refuses to begin a charge cycle — it reads the pack as faulty rather than depleted. This is a threshold issue, not a defective battery. Seat the handset firmly in the base, leave it undisturbed for two to four hours, and the base will usually begin charging once the resting voltage climbs slightly. If the error persists, a brief trickle charge from a standalone Ni-MH charger at 60mA for 30 minutes typically brings the pack above the acceptance floor.

Range dropping noticeably after swapping in a new battery

DECT transmit power on these handsets is tied directly to supply voltage. When a Ni-MH pack is not yet conditioned — typically the first three to five cycles — voltage sags under the RF load of active transmission, and the handset reduces output power to compensate. The result is shorter range and occasional call drops near the edge of coverage, even with a brand-new battery. Run three full charge-and-discharge cycles through normal use, and the range returns to normal as the cells reach rated capacity. Do not judge range performance until after cycle five.