I suspected I would get a lot for funny replies. Since my calculator is a museum piece, no one ever touches it. I'm not a battery expert but the code "C8501" could it be the supposed expiry date [Jan '85]. The irony is that the manual mentioned that "the batteries that come with your calculator...
In 1984 I bought a CASIO scientific calculator fx-100 which included 2 AA 1.5V alkaline Casio batteries [Casio Mabic C8501]. I have been using this calculator every single day throughout my student and professional life (total:28 years) with the SAME two batteries. I have written to CASIO asking...