$1,234 · 1920s 3 tube radio help needed.

In need of help , have a 3 tube shortwave radio, that run on batteries1922-1927. then switched to ac power supply 1928..wanting to run on batteries again, i have batterys ready to use but previous owner has not very clear + and - and V markings and do not want to fry anything, im a bit in over my knowledge base...any help will be appreciated. thanks.