Bongo Fury

This probably is a dumb question but how do I tell if my 2nd battery is set up as a leisure battery?

Do you have anything that would use a L/B ?
Disconnect the S/B and see if you can start the engine, if you can then you don't have a L/B !
Trace the wiring ?

Does the second battery positive run directly to the starter batt pos? (There might be an in-line fuse). If so, it's not a leisure batt.

If the wiring from it goes into a relay, or dissapears into the cab, then do what G8dhe suggests.

HTH

SD