Pat wrote: >Hello to the Group. My '46 415C seems to have an overloaded electrical = >system. The landing/nav lights, transponder and GPS/COM really pull some = >power [goes on to describe how some things have to go off so others can go on]...
Hmmm.
I'm not so sure I'm convinced that this is indeed the case.
When you add up the expected draw, versus the capacity of
generator and the reserves which should be in the battery,
they ought to be able to handle it. In fact, the real
smasher in this regard is the landing light. With everything
on, you might be running at a defecit (that is, the equipment
is consuming more than the generator is producing), but the
battery should make up for that for quite a while.
Before performing any transplant surgery, I'd look hard at the
wiring between the generator and battery, and particularly between
the battery and everything else. Primary leads can deteriorate inside
their connectors so that they won't carry high currents. All is fine
with just the radios on, but comes the landing light and you get
a huge voltage drop.
Also, sometimes the wire gauge is just too damned small. Someone
along the way might have replaced a fat wire with a skinny one.
Particularly in the case of long wires, they need to be fat at
12 volts in order to carry the current (that's the real reason for
28 Volt systems).
Look hard at the physical connections. Not just at the battery,
but at places like the fuse block. If it isn't soldered, take
it off and look. You may find ugly green stuff between the strands
of the wire. Or a lot of tarnish where it was clamped down.
Don't neglect the ground leads. What goes up must go down, and
poor connections here can be a problem. If a copper or steel
ground lead is bonded to aluminum, a high-resistance connection
can occur over time. Naturally, the current-carrying capacity of
the ground system must be as good and high as that of the 'hot'
side. A surprising number of electrical problems are traced to
a faulty grounding strap somewhere in the system.
Once the main, fat, wires that go out to the breaker or fuse panel
have been thoroughly overhauled, don't forget to look at the
wires out to individual devices. If the wire out to the landing
light is too small, or the connections dirty, it will have a
localized voltage drop which will make the light more sensitive
to low system voltage. Instead of getting 12 volts from a system
that has been loaded down from 13.6, it might get 10, which will
dim it noticeably.
Get the best battery you can, and keep it charged and the connections
clean. If the airplane is outside, maybe one of those solar trickle-
chargers would be a good idea.
Once everything is squeaky-clean, have the generator tested at a
shop that understands them (not many places do, but perhaps a place
that does antique auto electrical work does). Output of these guys
can sag quite a bit due to worn brushes and commutators. Unlike
alternators which, usually work fine or not at all.
It just doesn't sound to me like the load you're describing is
excessive for the capacity, unless you run the landing light all
the time. After all, the solid-state avionics probably draw about
one-tenth (in receive) or one half (in transmit) to what a 1955
vintage tube type set did.
Greg
--
Greg Bullough | AFM Local 1000 AFL/CIO
[EMAIL PROTECTED] | K2GWB
| PP-ASEL
www.eclipse.net/~gwb for Compass Rogues & NY Chantey Sings
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