A multi-series battery control system comprises a plurality of unit
battery cell of which unit consists of multiple battery cells connected
in series; a plurality of control IC comprising a control circuit for
controlling the unit battery cell; a main controller that sends and
receives signal to/from the control ICs via an insulation; means for
sending an abnormality signal, which represents the existence or the
absence of abnormality of the control ICs or the battery cells, to the
main controller from the control ICs, responding to the first signal
outputted from the main controller via the insulation; and means for
searching contents of the abnormality in the control ICs or the battery
cells and sending the abnormality contents signal based on the search, to
the main controller from the control ICs, responding to the second signal
outputted from the main controller via the insulation.