The batch thermal fixing scheme for multiplexed holograms is investigated. The dynamic behaviors of both electrons and ions in the case of light illumination and elevated temperature are theoretically analyzed, and hereby the optical erasure effect of subsequent recording light on ion-compensated electronic gratings is presented. The inter-batch optical erasure time constant, τF, is theoretically introduced, to evaluate the optical erasure to electronic gratings compensated by ions. The special experiment for measuring the parameter τF is designed and performed. The experimental result shows that inter-batch optical erasure time constant, τF, is much longer than intra-batch optical erasure time constant, τE, which agrees well with the theoretical prediction. Owing to the difference between τF and τE, the batch thermal fixing is an effective technique to achieve nonvolatile high-capability holographic storage.