About this replacement
Bosch 738 / CT-COM Series — 3.6V Ni-MH Replacement Battery
This is a 3.6V, 1200mAh Ni-MH battery for the Bosch 738 cordless DECT phone handset. It also fits the CT-COM 147, CT-COM 157, CT-COM 214, and 44 additional models in the same cordless phone family. When the original pack degrades and the handset stops holding charge, this is the direct swap.
- 738 and CT-COM series compatibility: These models share the same 3.6V three-cell Ni-MH bay, connector orientation, and charge-control circuit. The base station manages charge rate through a contact-voltage handshake — same spec across the entire family.
- Bench tested on actual hardware: We ran this pack through the Bosch base charge circuit and confirmed the termination voltage triggers correctly. The NiMH charge controller in the base accepted the pack without error and cycled normally through charge and standby states.
- First-charge protocol for NiMH cordless phones: After fitting, place the handset in the base cradle for a continuous 16-hour charge before first use. NiMH cells arrive partially discharged from storage, and the slow first charge is what brings each cell to rated capacity — skipping it leaves you with less than full capacity from day one.
Talk time shorter than original battery after replacement
NiMH cells need three to five full charge-and-discharge cycles before they reach rated capacity. A new pack straight out of packaging will underperform the spec — that is normal, not a fault. Each cycle trains the cells to accept and release a full charge. By cycle four or five, capacity should be at or close to 1200mAh and talk time will match expectations.
Base station showing no charge or flashing error light after swap
A new NiMH pack stored in a warehouse can drop below the voltage threshold the Bosch base station uses to confirm a battery is present and chargeable. If the base shows no charge indicator or a fault light, remove the handset, hold the power button for five seconds to discharge any residual circuit voltage, then reseat it firmly in the cradle. The base should detect the pack above its acceptance threshold — typically around 3.0V — and begin the charge cycle within 30 seconds.