Redundant charging and discharging MOSFET driving in battery backup system

Aspects of the disclosure relate generally to uninterruptible power supply units for systems requiring back up power. Each unit may include UPS circuitry for controlling charging and allowing discharging of a battery. The UPS circuitry may includes a controller and a plurality of metal-oxide semiconductor field effect transistors ("MOSFET") switches. The MOSFETs may include charging and discharging MOSFETs arranged in series with the battery all driven by a single gate driver, such as a controller. In this regard, the controller may limit the charging current though all of the MOSFETs and charge the battery. The MOSFETs may be arranged such that if the charging MOSFET fails, the redundant charging MOSFET may continue to limit the charging current to the battery. Similarly, a redundant discharging MOSFET may be arranged in series with a discharging MOSFET in order to continue to provide discharging current if the discharging MOSFET fails.