Hey!  I recognize that attached schematic ... from Klaus.  

It suggests using the aux battery to power just one ignition, but I think I'd rather have both ignitions and put in a heavier 9AH battery.  

How?  Would this work? Delete the power select switch, connect the power select terminals instead, add a second Schottky where the word MAIN is, and put a (power select -- now) voltmeter switch between the existing lead and a second lead from the voltmeter to the MAIN side of the added Schottky?

My fuzzy logic suggests that 

If both alternators are out, the CB(s) will pop; electrical use reduced, and then both batteries will power on longer.  When the voltmeter starts down, switching the voltmeter to read from either side of the second Schottky would tell whether the master battery is failed or not... and to land sooner?

Hmmm.  More complicated than just adding a battery, breaker, diode and switch.

Maybe I could just add a battery, the diode and breaker, the second diode,  and delete the power select switch Klaus calls for?

Terrence

On Jan 17, 2012, at 10:41 AM, Sky2high@aol.com wrote:

Terrence,

 

Yes.  You have jogged my creaky memory about the direct connect.  And yes.  See: http://www.periheliondesign.com/powerschottkydiodes.htm for the type I use because of the low voltage drop.  That is, it can be used to isolate the backup battery from the main yet still be charged in flight.  See attachment.

 

Scott

 

 

In a message dated 1/16/2012 1:42:32 P.M. Central Standard Time, troneill@charter.net writes:

Scott,

Ok.  

Since my LSI dual ignition and prop are hot direct from the battery, how about just adding plus and minus separate lines from the 2nd battery to the ignition and electric prop switches?

And, should I have Schottky diodes ... somewhere to keep the stby battery charged normally, yet isolate it in case of main battery shorts?

(Sorry for the simple questions... I'm electrically challenged.)

Terrence

On Jan 16, 2012, at 11:34 AM, Sky2high@aol.com wrote:

Terrence,

 

If you have a dual LSI ignition, you should have a backup battery for one of the ignitions.

 

Scott

 

In a message dated 1/16/2012 7:20:26 A.M. Central Standard Time, troneill@charter.net writes:

Brent,

here's mine.  I also have my AOA vane on the wing.  Have an Odyssey battery, B&C alternator and a backup small standby alternator; and a Garmin 396 w/ its battery.
Can't think of a senario where I couldn't maintain control if I lost all electrical, except 5 vdc for the LSI ignition.
Considering adding an small backup battery in parallel, or just for ignition. 
Comments invited.

Terrence
L235/320 N211AL


On Jan 15, 2012, at 9:39 AM, Brent Regan wrote:

> Ed Gray writes: "I have no steam gage backups.  With dual screens, backup batteries and dual ADHRS I feel that I have enough redundancy.  Does anyone have input or comment?  This plane may be one of the first with no round gauges anywhere."(sic)
>
> Dead man flying.
>
> Regards
> Brent Regan
>
> --
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