  Many applications, such as magnets and SMES, are usually charged and
discharged under a bias DC current, which may increase the AC loss. For their
design, it is necessary to understand and predict the AC loss. This article
analises the AC loss in magnet-like coils under DC bias contribution
super-imposed to the AC current. The analysis is based on a numerical model
that takes the interaction between magnetization currents in all turns into
account. The studied example is a stack of 32 pancake coils with 200 turns each
made of thin tape, such as $Re$BCO coated conductor. We present the current
density, the instantaneous power loss, and loss per cycle. We have found that
the loss increases with the DC bias current. The instantaneous power loss is
the largest in the initial rise of the the AC current. In following cycles, the
power loss is higher in the current increase than in the decrease. The loss per
cycle is the largest at the end pancakes. In conclusion, the highest cooling
power should be supplied to the top and bottom pancakes and during current
rise, specially the initial one. The presented model has a high potential to
predict the AC loss in magnet-size coils, useful for their design.
