Texas Instruments' bq25505 devices are specifically designed to efficiently extract the microwatts (µW) to miliwatts (mW) of power generated from a variety of DC energy harvesting, high-impedance sources without collapsing them. These sources include photovoltaic (solar) or thermal electric generators (TEGs). The battery-management features of the bq25505 ensure that a secondary rechargeable battery is not overcharged by this extracted power, with voltage boosted nor depleted beyond safe limits by a system load. The integrated multiplexer gate drivers autonomously switch the system load to a primary, non-rechargeable battery if the secondary battery voltage falls below the user-defined VBAT_OK threshold.