Uniden GMR1038 Replacement Battery 4.8V 700mAh Ni-MH

Uniden GMR1038 / GMR1448 Series — 4.8V Ni-MH Replacement Battery

This is a 4.8V, 700mAh Ni-MH replacement battery for Uniden GMR-series walkie-talkies including the GMR1038, GMR1048, GMR1438, and GMR1448. It slots into the same battery bay as the original pack and connects to the same contact array. Voltage and chemistry match the original Uniden specification exactly.

• GMR1038 / GMR1048 / GMR1438 / GMR1448 compatibility: These models share a common 4.8V Ni-MH power rail, identical battery bay dimensions, and the same three-contact interface. One replacement pack covers the full group without modification.
• Bench tested on actual hardware: We cycled this pack through full charge and transmit loads on a GMR-series unit. The BMS held stable through repeated PTT bursts without triggering overcurrent cutoff. Capacity measured within range of the 700mAh rating at room temperature.
• First-insertion contact check: If the charger shows a fault or blink pattern on first insertion, remove the pack and wipe the contact pads with a dry cloth before reseating. New Ni-MH packs ship at storage voltage — the charger dock on GMR-series radios requires clean contact to register the pack and begin the charge cycle.

Why the GMR1038 cuts out mid-transmission on a new battery

The GMR1038 draws a short current spike each time PTT is pressed to power the transmit stage. A Ni-MH pack at storage voltage — typically around 4.2–4.5V for a 4-cell pack — has higher internal impedance than a fully charged cell. That impedance causes a momentary voltage sag under the transmit load. If the sag drops below the radio's undervoltage threshold, the BMS cuts output before the transmission completes. A full charge cycle resolves this — transmit cutouts on a brand-new pack are almost always a storage-voltage issue, not a faulty cell.

Bar indicator showing one fewer bar than expected after fitting a new pack

The GMR-series bar indicator reads voltage thresholds directly — it does not track charge history. A new Ni-MH pack arrives at storage voltage, not full charge, so the radio correctly shows a lower bar count. This is not a calibration problem or a capacity fault. Charge the pack fully in the dock until the charger LED goes solid green, then power the radio on — the bar display will reflect the actual charged voltage, typically at or near the maximum indicator level.