REFLECTOR: Bus, Battery & Back Order

[Hiroo Umeno]

This is a timely thread for me as I am finalizing the firmware for the
annunciator panel MCU.  What voltage do you all trigger the low voltage
warning?  I am guessing that since alternator produce 14V and the
battery is at 12, simplistically it should be set to 13V or so, taking
the middle.  Is there a standard value that is the "industry standard"?

Also, somewhat related, does anyone have the voltage range for the
Westach capacitive fuel probe?  I've been scouring the web for the info
on this but the only thing I can find is 0 - 5V.  I somehow am hard
pressed to believe that it really is 0 - 5V rail-to-rail.  In reality, I
am guessing 0.5V to 4.5V or something like that.  Has anyone made
measurements?

-----Original Message-----
From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
Behalf Of Keith Hallsten
Sent: Thursday, June 16, 2005 9:11 AM
To: 'Velocity Aircraft Owners and Builders list'
Subject: RE: REFLECTOR: Bus, Battery & Back Order

Scott,

My point was to make sure that you have a low-volts warning that you
can't
miss, not that one set of hardware to accomplish that function was
required
over another.  As it happens, I plan to use the low volt warning that is
built into the B&C voltage regulator, but that's not because I think
there's
anything wrong with the warning from the EIS!  I already have the
regulator,
so the voltmeter function of the EIS just provides free redundancy.

Keith


-----Original Message-----
From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
Behalf Of Scott Derrick
Sent: Wednesday, June 15, 2005 9:00 PM
To: Velocity Aircraft Owners and Builders list
Subject: Re: REFLECTOR: Bus, Battery & Back Order

The GRT EIS already has a low voltage warning built in, with a panel 
mounted LED that lights up if any parameter is out of range, voltage 
being to high or to low being two of these alerts.

Why add another system to complicate things?  Or is the GRT EIS the 
system you were talking about.

Scott

Keith Hallsten wrote:

>Terry,
>
>That low-voltage warning light is the key item of electrical system
>instrumentation.  I have decided against an ammeter - I don't think it
tells
>me anything I need to know in flight.  I'm using a little SD-8 backup
>alternator on the vacuum pump pad, so my "main alternator out" drill
will
be
>to turn on the SD-8 and shed load until the low volts light goes out.
At
>that point I know that I'm not draining the battery, so it will be
available
>for the approach and landing phase.  A voltmeter and ammeter may be of
some
>use in troubleshooting on the ground, but I have no intention of
>troubleshooting in flight.
>
>We have plenty of panel real estate in the XL, so I don't see any
problem
>with 3.125" backup gauges.  My panel layout shows a lot of blank panel!
>
>Keith
>
>
>
>-----Original Message-----
>From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
>Behalf Of Terrence Miles
>Sent: Wednesday, June 15, 2005 8:16 PM
>To: reflector at tvbf.org
>Subject: RE: REFLECTOR: Bus, Battery & Back Order
>
>Keith,
>Thanks.  I should have mentioned that I also plan a big--very bright
low 
>voltage warning and guage.  That is the best argument for splitting off
the

>aux batt in flight and running only the the main batt---I mean the
situation
>
>when the alternator goes inop, you don't notice, now the batt drains
off
and
>
>your first indication is a dark silent cockpit.  Also planned is an
ammeter

>so I can watch the download and know what I have.
>
>Also on the GRT.  I have found to drop the EIS altitude and airspeed is

>looking like big dials 3.12 inch versus 2.25 inch versus none at all if
I 
>stay w/ the EIS.  My choice for Big dials due little are cheaper.
Little 
>altitude mean a single needle, little IAS means 180 kts max.  To get
over 
>about 220 kts you to buy tso'd stuff.  I am looking at $275 ias and 155
alt.
>
>Check out Stein air on autopilots.  TruTrak is announcing soon a
retangular

>shapped autopilot.
>
>see ya
>Terry
>
>
>
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