About this replacement
Motorola CT150 / CT250 / CT450 Series — 7.4V Li-ion Replacement Battery (HMNN4151)
This 7.4V, 2600mAh Li-ion battery replaces the original pack on Motorola CT150, CT250, CT450, and CT450LS two-way radios. It cross-references over 35 OEM part numbers including HMNN4151, HMNN4154, PMNN4017, and HNN9008. The CT series radios are compact portables used in security, retail, and hospitality environments where reliable shift-long communication is critical.
- CT150 / CT250 / CT450 platform fit: These models share the same battery bay footprint, connector pinout, and 7.4V voltage rail. The BMS handshake protocol is consistent across the CT series, so one pack covers all three variants without modification.
- Bench tested on actual hardware: We cycled this pack through full charge and discharge on the CT450 dock. The BMS held cutoff voltage correctly at both ends and showed no false overcurrent trips under simulated PTT transmit current draw.
- First insertion into the charger dock: If the dock shows a fault LED on first insertion, remove the battery, wipe the gold contact strip with a dry cloth, and reseat firmly. The CT series charger requires a clean contact cycle to accept the new BMS handshake before charging begins.
Why the CT450 drops to reduced TX power mid-shift on a new battery
New Li-ion cells ship at storage voltage — typically 3.6–3.7V per cell — not at full charge. Under sustained RF output, the radio's voltage regulation circuit sees marginal headroom and steps down transmit power to protect the transceiver. This is not a faulty pack. A full charge cycle before field deployment puts both cells above 4.1V and gives the radio the headroom it needs to hold rated TX power through a full shift.
Bar indicator shows one fewer bar than expected after inserting new pack
The CT series uses voltage-threshold bar indicators, not a fuel gauge chip. Storage voltage on a fresh Li-ion pack sits below the top threshold, so the radio displays one or two bars even on a brand-new battery. This clears after one full charge — the dock needs to bring each cell to at least 4.15V before the top bar threshold registers. Seat the battery in the dock and allow a complete charge cycle before reading the indicator.