What does the "EMERG BATT switch" and the associated phrase "(if starting battery installed)" mean? I could not understand what the "EMERG BATT switch" and its associated expressions (if starting battery installed) in the "INFLIGHT ENGINE RESTART" procedure in the emergency section of the Tecnam P2006T aircraft mean. Because even though I scanned the entire AFM of the aircraft, there is no information about the "EMERG BATT switch", which is referred to as the backup battery. Also, I didn't understand what was meant by the expression (if starting battery installed). I think I need a detailed answer. I am attaching to the question the image of the page where the procedure is and where these statements are mentioned.
While I have not worked on this type of aircraft, I believe that it has 2 separate batteries. One battery is used just for the starters. The second battery supplies power to the various aircraft systems such as lighting and avionics.
During normal operations the generators charge both batteries, but only the first battery is used for the starters and only the second batteries the rest of the systems. Placing the battery switch to emergency allows both batteries to power the starters. That way if something has happened to first battery, the second battery might still be able to restart the engines.