In an example, an apparatus includes a charger for rectifying a direct current charge from an input alternating current voltage. A battery pack stores the direct current charge in a first string of battery modules and a second string of battery modules. An inverter is connected directly to the battery pack and inverts the direct current voltage to an output alternating current voltage. In one example, the first string of battery modules is directly connected to the inverter in parallel with the second string of battery modules.