Abstract: Disclosed is a hybrid electrochemical cell having two (or more) sub-cells each with different cell chemistry. For example, a second electrochemical sub-cell has a metal fuel electrode with the same type of metal fuel in a first electrochemical sub-cell, but has a different battery chemistry than the first sub-cell. A controller is configured to selectively generate an electrical current from at least one sub-cell in a discharge mode and selectively apply an electrical current to at least one sub cell in a charge mode, e.g., by controlling an open or closed state of switches. The operating modes may be controlled based on input parameters.