A wireless process variable transmitter for use in an industrial process includes a process variable sensor configured to sense a process variable of the industrial process and provide a process variable sensor output. A battery power source includes a plurality of battery power banks each having a primary cell battery, a low voltage cut-off circuit electrically connected to the primary cell battery which provides an electrical connection to the primary cell battery while a voltage of the primary cell battery is above a threshold, and an ideal diode having an input electrically connected to the primary cell battery through the low voltage cut-off and providing a power bank output. A power sharing node has an input connected to the battery power bank output of each of the plurality of battery power banks and having a shared power output which provides power to circuitry of the wireless process variable transmitter.