Real Care Baby Simulator Batteries

My Family and Consumer Science Class has five Real Care Infant Simulators that we use to give real-world parenting experience to 8th graders.  RealCare Baby makes it possible for students to practice caring for an infant 24 hours a day with schedules based on those of real infants.  Babies cry for care at all hours, day and night and students must determine what Baby needs: feeding, burping, rocking, diapering.  Students wear a unique wireless ID to ensure accountability and baby's computer tracks its care and safe handling. A detailed assessment data is downloaded post-simulation which tells me, as the teacher, exactly how students performed in their care of baby.  

Our program has had these babies for seven years, and while our babies are in excellent condition, the batteries are only made for five years and they desperately need replacing.  I have had several instances this year where babies' batteries have died while at home with a student and the student does not get to experience the full simulation.  These batteries are $150 each and my program does not have the funds to replace them. Please help me keep my infant simulation program alive!