Tundra10
Joined: 14 Jun 2010
Posts: 102
Location: Scarborough, Ontario
|
 Posted: Sat Jan 31, 2015 5:53 pm Post subject: Electrical System with Dual Batteries & Brownout Prevent |
 |
|
Joe,
A couple of things you probably have already considered and discarded
(or have omitted for simplicity):
No over voltage protection is shown.
Perhaps feed the bilge pump switch from main bus, or otherwise ensure
it can be easily shut off when turning off master switches to avoid
accidentally draining the battery.
As shown, there is no way to operate the Avionics and Engine bus as an
E-Bus without powering the Main bus.
That said, I cannot come up with an elegant switching solution to make
that happen.
One option is an additional switch that operates both relays, but in
an emergency, it would be easy to flip off the master switches before
turning on the E-Bus switch. If this is an electrically dependent
engine with the ignition powered from the Avionics and Engine bus,
that would lead to a pretty scary moment.
Another option is to use 2-10 switches and use the center position for
the Avionics and Engine bus, although again, in an emergency, the
tendency might be to turn those switches fully off, since that is the
habit ingrained at the end of every flight.
A totally different approach, what about this ? Feed the coils of the
relays from the Avionics and Engine bus. So when either contactor is
engaged, both relays are engaged and stay engaged when the masters are
shut off. Interrupt the feed to the relays at the end of the flight
with a normally on momentary switch marked Engine Shutdown. This
doesn't give you the ability to manually engage the Avionics and
Engine bus before flight to do clearance delivery and configure
avionics (you could using a 2-50 switch), but you won't shut off the
master switches and accidentally turn off the electronic ignition in
flight.
If you have previously posted details, I missed them. Are you
planning to connect an electrically dependent engine to the Avionics
and Engine bus ? Perhaps consider a battery bus for the critical
items ?
Bob can confirm, but perhaps there are situations, like a shorted cell
in a battery that would prevent the alternator charging the good
battery. In that case, perhaps it is better to add a second
alternator and keep the cross feed open during flight. This
complicates the pilot's job a lot and after mulling this over for
quite a while, I ended up going with Z13-8 for my plane.
Depending how far you are from civilization when the single alternator
fails, perhaps a second alternator is a good idea ?
Hopefully there is something useful to you in the above.
Jeff Page
Dream Aircraft Tundra #10
| Quote: | Time: 06:45:38 PM PST US
Subject: Electrical System with Dual Batteries &
Brownout Prevent
From: "user9253" <fransew(at)gmail.com>
Attached is a diagram that I drew of an electrical system with two
engine-cranking
batteries and brownout prevention. It is intended for a seaplane that will
fly into remote lakes. Either battery can crank the engine. One of
the batteries
will run a bilge pump. If the engine is cranked using only one battery,
then the other battery will provide 12 volts to avionics to prevent brownout.
The electrically dependent engine will be powered by the same bus as
the avionics.
With multiple current paths through two contactors and two relays, the
chances of this bus losing power are slim. Good workmanship will
prevent short
circuits.
Go ahead and point out any faults with this diagram or give
suggestions. You
will not hurt my feelings. I want to fix any shortcomings or design errors.
I used Bob N's Z-19/RB as a staring point, although you might not
see any resemblance.
Joe
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=437846#437846
Attachments:
http://forums.matronics.com//files/dual_bat_brownout_prevention__202.pdf
|
| | - The Matronics AeroElectric-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?AeroElectric-List |
|
|
|
Get Email Distribution Too!
FAQ
Search
Memberlist
Usergroups
Register
Profile
Log in to check your private messages
Log in
