GRT Avionics

This connector is labelled 'GPS memory', and is connected to power. What happens if the EFIS is using backup power, in which case this is no longer powered? Will the EFIS still function?

That's on the HXr connector document? It should be labelled "Clock Power". It maintains the time/date clock on the processor so the HXr doesn't forget what time it is when the main power inputs are lost. On some older HX systems it may make the boot sequence more reliable or slightly faster but that hasn't been evaluated for the newer HXr hardware. If that input isn't working, the EFIS will supply the clock power internally while the main power inputs are working.

Found this old post. I do not have anything connected to A18. would this be why my flight log data output is dated 2002. My Clock has the right time but doesn't get the date. You can manually load the correct date but it seems to lose it after shut down.
Trying to get the correct date on flight log.

Sal wrote: ↑Tue Aug 31, 2021 12:51 am Found this old post. I do not have anything connected to A18. would this be why my flight log data output is dated 2002. My Clock has the right time but doesn't get the date. You can manually load the correct date but it seems to lose it after shut down.
Trying to get the correct date on flight log.

On an HXr, HX, or Horizon HS, yes. If the EFIS can't get the date automatically then it has to be set manually. The EFIS can get the time and date from NMEA0183 GPS inputs and some ARINC GPS inputs. It can get time from some ADS-B inputs but not date. There's no internal battery so the only way to keep the time and date while the power is off is to connect A18 to always-on power (through a 0.1A fuse or 10kohm resistor).

Jeff
What sort of drain on the battery would you expect.

Well, worst case, you’d have 12/10k = 1 ma of current. Typical battery is 20 amp hours, so you’d drain the battery in 20,000 hours, or about 2 years.

I measured it at about 40 microamps.

Thanks Jeff and Bob,
sounds like I should connect up A18

Jeff,
I have a mini and two HxRs. My mini has battery backup, and all three are connected so they share dimming, baro etc. Will they also share time if the Mini is kept up to date? If not is there a setting that would make that work?

The battery backup in the Mini doesn't power the GPS when the EFIS is off. It either powers the whole thing or nothing.

The EFIS will only share time from a GPS. If the Mini's GPS is receiving then it will share the time from the GPS. If an EFIS somehow has valid time without any other time inputs then that time won't be shared. Setting the time manually in the HXr won't share the time.