Accutronics has developed a high-energy density lithium-ion (Li-ion) battery system that complies with shipping and transport regulations due to its modularity. There are restrictions on the number and weight of batteries that can be shipped, and batteries with energy in excess of 100 Wh have additional restrictions placed on their transport. The Accutronics Intelligent Power Vault (IPV) off-the-shelf modular battery system draws energy from removable, sub-100-Wh Li-ion batteries and feeds them through a central controller. Energy systems with less than 100 Wh then can be manufactured whilst still complying with transportation regulations. Up to eight batteries can be built into one system, providing in excess of 700 Wh. Suitable for battery backup applications, the IPV consists of a control module on the exterior and slots for between two and eight battery modules. Each of the individual modules in the IPV is a compact 86.4-Wh rechargeable Li-ion battery, called the VR420. The whole assembly weighs less than 8 kg.