A method and arrangement is provided for estimating an initial value for
an internal battery temperature of a vehicle using a four zone process
that determines which of a predetermined set of time zones correlates
with a measured period of time for an engine of the vehicle being in an
engine-off condition. Once the time zone is determined, an initial
estimated value of the internal temperature of the battery is determined
as a function of a set of parameters correlated with the determined time
zone. The set of time zones include a holding time zone, a model based
estimation time zone which is greater in time than the holding time zone,
a first self-adjustment zone which is greater in time than the model
based estimation time zone, and a second self-adjustment time zone which
is greater in time than the first self-adjustment time zone.