Fw: REFLECTOR: dual batteries discussion

KeithHallsten KeithHallsten at quiknet.com
Fri Mar 11 23:53:52 CST 2005


Don,

Your logic seems good for your situation - if you are going to carry lead
anyway, you may as well have it do some work!

However, I am installing a little B&C SD-8 alternator instead of a vacuum
pump on the engine accessory pad.  I am using a light fixed-pitch prop, and
my pilot seat will have to support a bit more weight than yours does, so I
don't expect to need nose ballast.  I don't expect to use dual batteries at
this point, but if my weight-and-balance calcs show I need more weight in
the nose, that's a reasonable way to add it.  Isn't it great that we can
customize our systems to fit our needs?!

Keith

----- Original Message ----- 
From: Don19dw at aol.com
To: reflector at awpi.com
Sent: Thursday, March 10, 2005 1:10 PM
Subject: REFLECTOR: dual batteries discussion

About a year after first flight, I installed a second battery and additional
components for a dual battery system for the following reasons.
1) the additional battery weight in the nose of 30# moves CG forward for
more stable cruise flight.(My weight is 190# and I also carry 25# of lead
ballast under right rudder pedals when alone in front seats)
2) the dual batteries produce a large increase in starter cranking power
available for cold weather starts and in the event of a flooded engine
start.(definitely a big plus).
3) provides dual sources of electrical power if the alternator fails.
(Provides plenty of power for the one electronic ignition system and
necessary instruments for flight).
4) much cheaper solution for the alternator failure than installing a second
alternator.
Equipment details:
(a) 2 Exide Premium 60 batteries, 30# each, with side bolt terminals, no top
terminals, so batteries could be stacked one on top of the other inside
nose, clear of retractable nose gear.(See attached photo)
(b) the alternator splitter (blue finned box in lower left corner of
picture) is a marine component from West Marine.
(c) batteries installed with terminals outboard so cables are clear of nose
gear retraction
(d) also installed a separate ground terminal in gear wheel guide just above
splitter. (see photo) This allows me to check each battery voltage or charge
each battery thru open gear doors without having to remove top hatch.
(e) These are inexpensive auto batteries which do cause some corrosion of
nearby metal parts. However cleaning corrosion and covering areas with
Vaseline has solved that problem
As a point for discussion, I believe a dual battery system is a much better
electrical back up system than dual alternators.
Don White   N19DW  XL/RG




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