An uninterruptible power supply system, comprising: a back-up power supply comprising a plurality of primary battery banks arranged in parallel, wherein at least one of the plurality of primary battery banks is in a long-term storage state and one of the plurality of primary battery banks is in an operable state and is designated as a first working battery; a temperature control system configured to receive a temperature control input signal and, based thereon, maintain a temperature of the at least one of the primary battery banks which is in the long-term storage state at a refrigerated temperature, to maintain a temperature of the first working battery at a higher temperature, and to control the warming of one of the plurality of primary battery banks to be transitioned to the operable state; a plurality of battery condition sensors, wherein each battery condition sensor is configured to measure the condition of a corresponding primary battery bank of the plurality of primary battery banks; and a back-up power supply controller including one or more processors configured to: monitor the condition of the first working battery by monitoring the output of one of the battery condition sensors measuring the condition of the first working battery, determine if the condition of the first working battery is below a transition preparation threshold, responsive to a determination that the condition of the first working battery is below the transition preparation threshold, issue a temperature control input signal to the temperature control system to transition one of the primary battery banks previously maintained in the long-term storage state to the operable state, and responsive to a determination that the condition is below a retirement threshold, designate the transitioned primary battery bank as a second working battery and switch the source of the power provided by the back-up power supply from the first working battery to the second working battery. a back-up power supply comprising a plurality of primary battery banks arranged in parallel, wherein at least one of the plurality of primary battery banks is in a long-term storage state and one of the plurality of primary battery banks is in an operable state and is designated as a first working battery; a temperature control system configured to receive a temperature control input signal and, based thereon, maintain a temperature of the at least one of the primary battery banks which is in the long-term storage state at a refrigerated temperature, to maintain a temperature of the first working battery at a higher temperature, and to control the warming of one of the plurality of primary battery banks to be transitioned to the operable state; a plurality of battery condition sensors, wherein each battery condition sensor is configured to measure the condition of a corresponding primary battery bank of the plurality of primary battery banks; and a back-up power supply controller including one or more processors configured to: monitor the condition of the first working battery by monitoring the output of one of the battery condition sensors measuring the condition of the first working battery, determine if the condition of the first working battery is below a transition preparation threshold, responsive to a determination that the condition of the first working battery is below the transition preparation threshold, issue a temperature control input signal to the temperature control system to transition one of the primary battery banks previously maintained in the long-term storage state to the operable state, and responsive to a determination that the condition is below a retirement threshold, designate the transitioned primary battery bank as a second working battery monitor the condition of the first working battery by monitoring the output of one of the battery condition sensors measuring the condition of the first working battery, determine if the condition of the first working battery is below a transition preparation threshold, responsive to a determination that the condition of the first working battery is below the transition preparation threshold, issue a temperature control input signal to the temperature control system to transition one of the primary battery banks previously maintained in the long-term storage state to the operable state, and responsive to a determination that the condition is below a retirement threshold, designate the transitioned primary battery bank as a second working battery and switch the source of the power provided by the back-up power supply from the first working battery to the second working battery.