REFLECTOR: POWER GUARD

[David Scharfenberg]

Hi Terry,

    Glad to hear that the building is going well.  I guess in the 
beginning I was concerned about the electronic ignition, and wanted to 
keep a fully charged battery just for it in case of an alternator 
failure.

Dave



On Aug 24, 2005, at 7:49 AM, Terry Miles wrote:

> 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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