Simplest Inline Battery Backup Mini EFIS

[Rich_Klarich]

Is there a schematic for the absolute simplest, in-line, backup battery?

The mini has 1 power input.

I have a standard single alternator and main battery with a zeftronics extrnal voltage regulator and overvoltage relay/crowbar. Standard master solenoid to the diode and switch-split essential and normal busses.

I have the footprint for the mini if I remove the current, only steam gauge, a 3-1/8 ASI, meaning pitot and static are ready to go in the right location.

I would like to put a 2 to 3 AH, 12v SLA battery to a Mini EFIS on its own circuit.

A SPST switch and 2 Amp fuse or CB would connect this battery and mini to normal buss power and charge the small SLA battery. It would be uphill of the diode to give full alternator voltage.

A second 1 Amp fuse and switch or circuit breaker switch would apply that power from the 2 or 3AH SLA battery to the mini efis itself. A small led voltmeter would also be on this line and mounted by the mini EFIS and switch as I don't see volts on the mini efis.

I have a EIS 4000 and Sport HS200 SV. I don't need the mini X or OAT or extra magnatometer for the Mini, I fly VFR though I am an IFR pilot and thr plane has an SL30 and TRUTRAk 385. If I were to lose power at night, the MINI and a 3AH battery give me a huge safety gain.

That is what I seek.

The D-1 is cute, my droids all do the same, but since I have pitot and static ready for a "real" instrument- The Mini B looks far better.

Thoughts?

[GRT_Jeff]

Several planes are using Paul Dye's electrical design which includes an aux battery for EFIS backup. Your plan sounds similar. His system uses diodes to handle switching between the aux battery and other sources, and resistors to limit charge current. The diagram at the top is missing some of the protection parts and maybe a diode, which you can read about in the text.
http://www.vansairforce.com/community/s ... hp?t=73527

You are correct that the Mini doesn't currently have a way to show the input voltage on the PFD page. I expect we will be adding some selectable data fields to the PFD in future software.