This paper discusses new developments in lead-acid battery chemistry and the importance of the system approach for implementation of battery energy storage for renewable energy and grid applications. The described solution includes thermal management of an UltraBattery bank, an inverter/charger, and smart grid management, which can monitor the state of charge (SoC) and the state of health (SoH) of the battery during system operation. With such features, it can allow the battery to operate within an optimum SoC window and thus can further maximize the longevity of the UltraBattery. Importantly, the smart battery management can trend the SoH of the battery and allow cell replacement at a convenient time without affecting the system operation. Furthermore, the advanced system package allows remote monitoring and control of operation, thus reducing the running cost of the system. It is clear that the widespread use of renewable-energy systems, in turn, would lead to a reduction in global consumption of the limited supplies of the fossil fuels and in the associated production of greenhouse-gas emissions.