A battery or battery system containing one or more failing battery cells and/or containers may not be capable of providing power at rated operating voltages, currents, and/or time durations. For example, lead acid batteries lose their ability to accept a charge when discharged over a period of time. Even if maintained on a battery charger, lead acid batteries will eventually fail over time due to sulfation. Ohmic value also known as internal cell resistance or impedance and cell conductance. When a battery cell starts to fail the internal resistance of the battery cell increases. Ohmic value is known to be temperature dependent.
One usage for lead acid batteries is within high capacity uninterrupted power supply (UPS) systems. Typically, the high capacity UPS system is provided in the form of a number of lead acid battery cells electrically connected in series. Historically, these lead acid batteries have been characterized for an operating temperature like 77° Fahrenheit (25° Celsius) and are often used in a climate-controlled environment. A battery monitoring system may be used with the high capacity UPS system to routinely check and determine a state-of-health for each cell by measuring the cell ohmic value at 77 F. As such, dying cells can be detected and replaced prior to a failure. However, there are applications which use the battery and charger systems in extended temperature environments without climate control.
As such, new methods, systems, and devices are needed to better determine the state-of-health of battery systems (e.g. high capacity UPS systems) over extended temperature ranges. Additionally, other outdoor batteries may benefit such as vehicle batteries.