A coin cell powered device includes a regulator, a transmitter and a charge pump. The transmitter is configured to transmit signals during a transmission period while receiving power from the regulator, the power originated from an external capacitor. The charge pump is configured to perform, during a charging period, a charging process for charging the external capacitor to a charged voltage that exceeds a voltage of a cell coin, wherein the charging process may include iterations of (a) charging a charge pump capacitor by the coin cell, and (b) discharging the charge pump capacitor thereby charging the external capacitor. The capacitance of the charge pump capacitor is a fraction of a capacitance of the external capacitor. The duration of the charging period exceeds a duration of the transmission period.