REFLECTOR: POWER GUARD

[Terry Miles]

Hi Dave,
 
Good to hear from you.  Thanks for the explanation.  That is my first
inclination on this wiring setup too--separate relays. But the
literature on these Marine Switching units sound pretty slick.   But let
me ask--if I don't sound too dumb--why (in the case of alternator inop)
would you isolate your batteries?  Why not just leave them in parallel
ops when on batt power only, as opposed to running them down one at a
time?  Except to do a preflight separate voltage check, I see am
inclined to see them as one big batt.  A big part of the why of dual
batts for me is wgt and bal.  
 
For wiring simplicity, I am moving away from dual/multiple bus configs
in event of alternator failure, and plan on a manual download myself of
on/off switches and deliberately grouped CBs for fast load shed.  Only
exception might be a hot battery bus on batt #2 alone with a feed an
EFIS that (by manufacturer design) will accept three separate power
sources and automatically grabs the highest Voltage sense.  
 
Seems like I would have to be asleep a long time for the Alternator to
go out, have the low volt warning illuminated, and then run the primary
batt down, and have things go dark on you before I woke up and switched
to a "standby" battery.  This paragraph is the only reason I can come up
with to isolate dual batts in flight.  ...but I am a willing student.
Lightening strike?  
 
Thanks for your thoughts!
 
Big day down here today.  We are planning to put the top on.  We had 2
heat guns on the top flange of the firewall bulkhead due top flange was
angled up and seemed to be the high point.  While it was still hot and
malleable we dropped the top (still just dry fit) in hopes of bending it
back flatter.  It helped some.  Two noses lined up great.  No big
problems with sidewall line up.  The dust will fly today!
 
Terry

-----Original Message-----
From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
Behalf Of David Scharfenberg
Sent: Tuesday, August 23, 2005 11:46 PM
To: Velocity Aircraft Owners and Builders list
Subject: Re: REFLECTOR: POWER GUARD



On Aug 22, 2005, at 8:52 PM, Terry Miles wrote:




Does anybody else out there have a dual batt, single alt configuration?
 
Regards,
Terry




Terry,

I have two 17 amp/hr sealed batteries and one alternator. Each battery
has it's own relay, and switch on the panel. If I get a low volt light
(which comes on within seconds of the alternator going off line), I can
simply switch one battery off if I want to isolate it. That way both
batteries get full charging voltage, as opposed to charging through a
diode with it's resultant voltage drop.

Dave Scharfenberg
std/rg


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