Efficient, high power battery module; D.C. transformers and multi-terminal D.C. power networks utilizing same

Multiterminal, high voltage D.C. power networks in which the sub-terminals are electrically isolated from each other comprise D.C. transformers, as the terminals. Each transformer comprises a large number of efficient, high energy batteries, connected as two separate groups: one group made up of paralleled long strings of series connected batteries and the other group made up of paralleled short strings of one or more batteries each. Each transformer also comprises automatic monitoring, control and switching means for periodically exchanging charged and discharged strings between the two groups, one of which-the "primary"-is connected across the supply lines from the power source(s) for the network and the other of which-the "secondary"-is connected across the service lines providing power to users thereof.