Internal battery

hey guys hoping one of you can help me out.
I am currently trying to repair a Hitachi U-2000 UV/VIS spectrophotometer. After fixing many initial problems and hours of research i finally found the root cause of one of the main problems. A dead battery. apparently these machines go into some default settings and will not work at all and make the user think there is a serious problem to get them to pay for a representative to fly out and fix it. Any way i am trying to identify what the internal battery looks like, and its relatively difficult because its older and has several boards. I am familiar with what new batteries look like, but if someone has some pictures of what i may be looking for that would be greatly appreciated.. I know its a long shot, but any input is helpful and i can put pictures up of what im dealing with if that helps thaks all