Abstract: Disclosed herein is a modular battery system having at least one set of battery modules, preferably monoblock modules connected in series. Each of the battery modules may be designed with a first endplate and a second endplate, wherein each battery module is set between the first and second endplates and at least one band member couples the endplates to each other, binding the battery module between the endplates. The endplates are secured between a pair of rails and the system is disposed in a system housing. A cooling manifold provides a system wherein coolant flows into and out of each battery module. The system housing preferably has a coolant inlet and a coolant outlet. The cooling manifold is in flow communication with the coolant inlet and the coolant outlet. A battery monitoring system, which may include a battery control module and at least one remote sensing module, preferably monitors and collects performance and status information, such as voltage and temperature, of the battery modules.