EMS Battery Backup

[Dwillows]

I’m an E-LSA newbie…. Just starting to fly my recently completed RV-12iS and trying to understand the panel switch “Backup EMS Battery Switch”.

I understand that Generator A can provide some power to the main bus if that switch is turned ON.

But what/where is the Backup EMS “Battery”? I assume that battery is not the main starter battery, nor the Garmin Backup EFIS Battery.

 

[jrtens]

From the Flight Training Supplement: The switch basically allows the main (one and only) battery to power the 912iS during dual generator failure.

 

[CTCole]

You're right, this is a confusing term. If you look through the wiring diagram in the POH, you will see that there is not a backup battery for the engine (there is a backup battery for the PFD/EFIS system, but that is up in the avionics compartment-- slightly different between the Garmin and Dynon systems). If the generators quit, you can turn on the "EMS Backup Battery" switch and it will connect the the aircraft battery to the fuel pumps and engine computers, which will power while you look for a place to land.

 

[Dwillows]

You're right, this is a confusing term. If you look through the wiring diagram in the POH, you will see that there is not a backup battery for the engine (there is a backup battery for the PFD/EFIS system, but that is up in the avionics compartment-- slightly different between the Garmin and Dynon systems). If the generators quit, you can turn on the "EMS Backup Battery" switch and it will connect the the aircraft battery to the fuel pumps and engine computers, which will power while you look for a place to land.

View attachment 117229

Thanks gents, you clarified that the battery referenced is the main (starter) battery. I appreciate your responses, many thanks.