Batboard

So I am unable to locate the DIU Service Manual 68P02949C75 on MOL, only could find the Basic Ops Manual. So my question is what battery does the DIU 3000 need internally? I located it on the encryption cartridge slot looks slightly shorter than a AA battery and does it need to be chargeable?

Thank you for your help

CR123A and no, it's not charged by the DIU.

Thank you MattSR for the help.