REFLECTOR: Battery Isolator

[michalk]

I don't have access to my schematics right now.  I can describe it 
easily enough though.

There are three posts on the combiner.  One for each battery, and one 
for ground.  It's quite simple, just connect each post to a battery. 
The ground wire does not need to be very large.  For the battery 
connections, about 10 gauge should do it.  The alternator charges the 
essential bus.  When charging, the two busses are combined.

I do see merit in the manual Nuckolls method.  It's a tradeoff.  I 
wanted it automatic, and less wiring.

I have two battery busses, but one alternator.  My backup bus is not for 
engine cranking, so that battery is two motorcycle type batteries on 
each side of my main battery.  I plan to swap out a battery at each annual.

I do have a "join" switch, but it's for powering the essential bus off 
the main battery.  You can't start the engine with it.

My essential bus powers the Autronic electronic ignition/injection, and 
avionics.  I did a load test, which is not entirely accurate because the 
load on the Autronic scales with RPM.  Accounting for that overhead with 
an estimated flying load, my batteries should keep the airplane flying 
for ten hours.  Make sure your battery capacity is longer than your fuel 
capacity.

Even if the Autronic loses power, the backups would still work.  My test 
was with all of the gyros and radios working ... a worst case scenario 
minus the pitot heat.  If I turned off everything but the gyros I 
imagine my flight time would be extended beyond 20 hours.  However, 
that's not the main intent of multiple systems.  Redundancy is what one 
is after.  A failure analysis is interesting.  In my case, it's the fuel 
pressure regulator that is the weak link.  Finding data on failure rates 
of equipment can be difficult, so one has to make assumptions and make 
sure those components are frequently inspected or replaced.

Anyway, I'm preaching to the choir here.  My plane is all electric. 
That means my systems need to have electrical redundancy.  Vacuum guys 
have a redundant system with it's own set of failure points.

You still want that schematic?

Alex wrote:
> Hey Brian-
> Can you send me a schematic of how you installed the West Marine isolator? I
> have one also- and trying to make sure I get it in there correctly-
> currently have separate relays for each battery installed, and I have a
> cross over relay , but not sure if I will still need it or not...... 
> 
> Alex
> alex157 at pwhome.com
> 
> -----Original Message-----
> From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
> Behalf Of Michael Watson
> Sent: Tuesday, January 02, 2007 11:51 AM
> To: Velocity Aircraft Owners and Builders list
> Subject: Re: REFLECTOR: Battery Isolator
> 
> Thanks Kurt/Brian,
> 
> Any comments AL.
> 
> I was looking at the ASE Sure-Power 70Amp unit for $40.
> Guess I'll buy and try it.
> 
> Mike W.
> 
> 
> On 1/2/07, Brian Michalk <michalk at awpi.com> wrote:
> 
>>I'm using a marine battery isolator from West Marine.  Seems to work 
>>okay so far.  Not flying yet.
>>I voided my warranty by opening it up to see the guts.  Simple 
>>comparator circuit with time delay which drives a relay.  When either 
>>battery is being charged, they are connected together.
>>
>>A person could easily make one, but for the $50 or so, it's not worth it.
>>
>>We use the solid state ones at work, and they seem to work okay.
>>
>>Michael Watson wrote:
>>
>>>Does anyone using dual batteries with an internal regulated 
>>>alternator, have a good source and part number for a battery 
>>>isolator? Thanks.
>>>
>>>--
>>>Mike W
>>>Velocity Elite RG
>>>Franklin /IVO Electric CS
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