  The Josephson effects in two weakly linked Bose-Einstein condensates have
been studied recently. In this letter, we study the equations derived by
Giovanazzi et. al. [Phys. Rev. Lett. 84, 4521 (2000)] focusing on the effects
of the initial acceleration and the velocity of the barrier on the ``dc''
current. We find that the dc current has lifetime which critically depends on
the moving velocity of the barrier. Moreover, the influence of the initial
acceleration is also investigated and found to be crucial for the experimental
realization of the effects.
