25 April 2020

Avionics: Installed backup battery for Horis AI

Back in November of 2018, I replaced my old-school TruTrak ADI2 backup AI with a Kanardia Horis 57.  I don't have backup power in my airplane, but I decided that the backup AI ought to have backup power just in case things fall apart in the soup.

Kanardia makes a UPS-L for just this purpose, spec'ing that it can run the Horis 57 for 190 minutes.  At only 4.2 ounces, that seemed like a good option.


I placed it on the subpanel in the only remaining space something could fit.

I discarded the DPDT switch that Kanardia provides in favor of the Otto K1/K2 series switches that I have on my panel (go here to see the model numbers of most of my switches).  They have one throw of that switch controlling the state of the UPS ("on" or "off") and the other side physically disconnecting the UPS from the device it is powering.  I decided that it was only necessary to control the state of the UPS and physically disconnecting wasn't necessary, so I only needed an SPST or DPST switch.  

On my panel, red switches are thematically switches that don't need to be on all the time.  They also have a red light.  So for the UPS, I thought a red switch with a green light would be appropriate.  Technically, the UPS need not be on all the time (so, red switch), but the green light would mean that it's okay if it's on.  I would need an independent light on the switch since the state wires on the UPS are logic level to ground.  I decided that the light should be powered by the UPS, so it I forget to turn if off when the Master is off, not only will my Horis still be on, but the green light will be too.

When I designed my panel originally, I thought to add a slot for a switch I might add in the future.  I plugged it with a blank.  Well, turns out that the future finally came.


The Otto K1AABPCADA switch fit the bill.  And adding a label was easy with my label maker.

No comments:

Post a Comment