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Kellym
Joined: 10 Jan 2006
Posts: 1700
Location: Sun Lakes AZ
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 Posted: Tue Jan 27, 2015 4:43 pm Post subject: Dual Alternator, Dual Battery, Single Bus |
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I believe you heard the information backwards, since Dynon's printed
manuals up through the current revision of a week ago say to start the
engine with the Dynon on, and mention nothing about starting on a backup
battery. It just says that if you want the EFIS to be on during start
that you should install a Dynon backup battery for the EFIS. The Dynon
itself controls switching to its backup battery, which is connected only
to the Dynon, not to the system buss, and it keeps the Dynon alive while
you are cranking.
Perhaps it is just a communications problem, that what you are trying
to say is what the Dynon manuals say. You crank on the Ship's battery.
The EFIS is kept alive via its backup battery, which isolates the
display from the system buss when voltage drops below its minimum, and
keeps the system up with power from its backup battery.
On 1/27/2015 2:44 PM, ARGOLDMAN(at)aol.com wrote:
| Quote: | Actually,
That information came from a conversation that I had with Dynon's Tec.
When I asked him how do I monitor my oil pressure ect on startup he
told me about starting the engine on the backup battery.
So if you start the engine with the skyview attached to the system bus
and you get the electronic glitch that would reboot your system, by
the time it reboots and is able to give you an oil pressure reading
you may have toasted your engine. Are they just talking about the
starting draw decreasing the voltage to the point of resetting or the
transients caused by starting when they talk about the use of
auxiliary power on startup. My understanding, possibly wrong is that
the dynon battery is automatically connected in the case of low
voltage. If low voltage is the case, does the switchover happen
quickly enough to prevent the reboot? If a transient situation does
the small aux battery have the capability to filter it out?
Additionally the installation/operation instructions for the ICOM
A-200 (not really an ancient radio) state,
"Do not turn the power on until after the aircraft engines have been
started. This is important for the protection of the circuit."
If you are concerned about single point failure, nothing stops you
from having a duplicate avionics switch. I have duplicate fuel pump
switches (located in different places).
Rich
In a message dated 1/27/2015 9:50:01 A.M. Central Standard Time,
fransew(at)gmail.com writes:
<fransew(at)gmail.com>
> TO MINIMIZE THE CHANCE OF THE SYSTEM RESETTING DURING ENGINE
CRANKING, THE OPTIONAL REDUNDANT (DIODE OR'D) POWER INPUTS MAY BE
CONNECTED TO AN AUXILIARY BATTERY . . .OR STABILIZED POWER INPUT. . .
The Garmin manual does not recommend using backup power during
engine start. It says that OPTIONAL backup power MAY be used.
Both Garmin and Dynon say that having optional backup power will
prevent rebooting during engine cranking, which I think is a good
idea because rebooting is annoying. But neither company says that
not having backup power will damage their units. And neither
company recommends disconnecting their units from the aircraft
electrical system during engine starting.
The point that I am trying to make is that an avionics master
switch to protect avionics is unnecessary. Installing an avionics
master switch introduces a single point of failure. If that
switch fails, avionics go dark.
Joe
--------
Joe Gores
Read this topic online here:
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Kelly McMullen
A&P/IA, EAA Tech Counselor # 5286
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Kellym
Joined: 10 Jan 2006
Posts: 1700
Location: Sun Lakes AZ
|
| Posted: Tue Jan 27, 2015 4:46 pm Post subject: Dual Alternator, Dual Battery, Single Bus |
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The Dynon backup battery is a rechargable lithium battery of some sort,
which the Dynon Skyview system controls the charging rate, and it maxes
out around 12.2-12.25 volts. It requires you run a battery test at least
once a year to ensure 1 hour of capacity.
On 1/27/2015 3:07 PM, Justin Jones wrote:
| Quote: | I would be interested in looking at the circuitry of the standby
battery from dynon. Does anyone know if there is a diode that allows
current to flow from the standby battery to the dynon but not back
into the battery?
Seems that you would either have a need for a replacement standby
battery, or you would have a need to recharge the dynon battery
somehow (if it were rechargeable) when the standby battery dies.
Justin
On Jan 27, 2015, at 12:44, ARGOLDMAN(at)aol.com
<mailto:ARGOLDMAN(at)aol.com> wrote:
> Actually,
> That information came from a conversation that I had with Dynon's
> Tec. When I asked him how do I monitor my oil pressure ect on startup
> he told me about starting the engine on the backup battery.
> So if you start the engine with the skyview attached to the system
> bus and you get the electronic glitch that would reboot your system,
> by the time it reboots and is able to give you an oil pressure
> reading you may have toasted your engine. Are they just talking about
> the starting draw decreasing the voltage to the point of resetting or
> the transients caused by starting when they talk about the use of
> auxiliary power on startup. My understanding, possibly wrong is that
> the dynon battery is automatically connected in the case of low
> voltage. If low voltage is the case, does the switchover happen
> quickly enough to prevent the reboot? If a transient situation does
> the small aux battery have the capability to filter it out?
> Additionally the installation/operation instructions for the ICOM
> A-200 (not really an ancient radio) state,
> "Do not turn the power on until after the aircraft engines have been
> started. This is important for the protection of the circuit."
> If you are concerned about single point failure, nothing stops you
> from having a duplicate avionics switch. I have duplicate fuel pump
> switches (located in different places).
> Rich
> In a message dated 1/27/2015 9:50:01 A.M. Central Standard Time,
> fransew(at)gmail.com <mailto:fransew(at)gmail.com> writes:
>
>
> <fransew(at)gmail.com <mailto:fransew(at)gmail.com>>
> > TO MINIMIZE THE CHANCE OF THE SYSTEM RESETTING DURING ENGINE
> CRANKING, THE OPTIONAL REDUNDANT (DIODE OR'D) POWER INPUTS MAY BE
> CONNECTED TO AN AUXILIARY BATTERY . . .OR STABILIZED POWER INPUT. . .
>
> The Garmin manual does not recommend using backup power during
> engine start. It says that OPTIONAL backup power MAY be used.
> Both Garmin and Dynon say that having optional backup power will
> prevent rebooting during engine cranking, which I think is a good
> idea because rebooting is annoying. But neither company says
> that not having backup power will damage their units. And
> neither company recommends disconnecting their units from the
> aircraft electrical system during engine starting.
> The point that I am trying to make is that an avionics master
> switch to protect avionics is unnecessary. Installing an
> avionics master switch introduces a single point of failure. If
> that switch fails, avionics go dark.
> Joe
>
> --------
> Joe Gores
>
>
> Read this topic online = Use utilities Day
> ================================================ -
> MATRONICS WEB FORUMS
> ================================================ - List
> Contribution Web Site sp;
> ===================================================
>
> *
> *
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| | - 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 |
|
_________________
Kelly McMullen
A&P/IA, EAA Tech Counselor # 5286
KCHD |
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