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Don Owens
Joined: 17 Jan 2006
Posts: 24
Location: North Central Washington
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 Posted: Tue Nov 21, 2006 9:20 am Post subject: Duel LSI ignitions (No mags) |
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Hi all, I would like some input on what would make others feel comfortable when powering duel electronic ignitions. I plan to have night and IFR capability in an RV-7. I have looked at Bob's schematics: Z-12 and Z-14. The Z-14 certainly covers all the bases, but I hate to hang an extra battery up front if it is not absolutely necessary. I am thinking that the Z-12 with the B&C 40 amp alternator up front and a B&C 20 amp alternator on the vacuum pump pad and a 17 amp/hr battery that would be redundancy enough. Am I living on the edge?
Thanks for the input
Don Owens
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frank.hinde(at)hp.com
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| Posted: Tue Nov 21, 2006 10:18 am Post subject: Duel LSI ignitions (No mags) |
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Here is what I have.
No mechanical fuel pump...two FI electric pumps one in each wingroot.
Emag and Pmag (Pmag is self powering)...If I could have been certain the
SD8 had enough guts I would have bought 2*Emags.
I have a GNS430,main buss
GTX 327, Icom A200 (wired to endurance buss)
Odyssey 18AH battery.
Last night I ran the SD8 on the ground and was very surprised to find
that at only 2000RPM (lycoming) I had enough power to run one fuel pump
and all the electronics...This includes the main contactor. Certainly if
I added any lights the batt volts would drop.
Now if my main alt died in flight I might still switch over to the
endrance buss and shutdown the Emag and run the RPMs to 2600. But it
seems I don't have to go mad about turning everything off I can to
maintain 12.2v at the battery. In real life if I was cross country IFR I
would probably go to the minimum, i.e turn off the 430 and audio
panel...But hand fly vectors from ATC...Making sure I have plenty of
charge to the Odyssey.
I suspect the SD8 makes more power than advertised. This is intened as a
night IFR machine.
Frank
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bob(at)flyboybob.com
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| Posted: Tue Nov 21, 2006 2:34 pm Post subject: Duel LSI ignitions (No mags) |
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Don,
I'm right there on the edge with you. I've got dual electronic ignition and
a modified version of Z-13. I have a second battery buss that only powers
the secondary ignition and fuel pump. That way the only single point of
failure is the bolt at the battery post. Can you say loc-tite, castle nut
and safety wire! The secondary ignition will be grounded directly to the
battery also. I have a 40amp primary alternator and a 20 amp back up dynamo
that runs on the endurance bus so if the master contactor craps out I'm
still flying with half power (electrical).
Regards,
Bob Lee
N52BL KR2
Suwanee, GA
91% done only 65% to go!
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klehman(at)albedo.net
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| Posted: Tue Nov 21, 2006 8:05 pm Post subject: Duel LSI ignitions (No mags) |
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Sounds reasonable to me as long as like the B&C 8, the B&C 20 runs fine
with the big capacitor in the circuit but no battery?
FWIW I am running Z-14 with two 8 AH batteries for the same total
battery weight although more expense. They parallel during cranking but
one will start the subaru just fine. I've found that with a dead battery
my John Deere PM alternator pops the overvoltage protection and fries
the regulator so it would likely be useless without a battery in the
circuit such as after a failed battery contactor or whatever. Probably
overkill but the nice thing about Z-14 is that my two ignitions etc. do
not share any common parts or wiring.
Ken
Don Owens wrote:
| Quote: |
Hi all, I would like some input on what would make others feel comfortable when powering duel electronic ignitions. I plan to have night and IFR capability in an RV-7. I have looked at Bob's schematics: Z-12 and Z-14. The Z-14 certainly covers all the bases, but I hate to hang an extra battery up front if it is not absolutely necessary. I am thinking that the Z-12 with the B&C 40 amp alternator up front and a B&C 20 amp alternator on the vacuum pump pad and a 17 amp/hr battery that would be redundancy enough. Am I living on the edge?
Thanks for the input
Don Owens
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Roger Bentlage
Joined: 27 Oct 2006
Posts: 6
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| Posted: Wed Nov 22, 2006 7:15 am Post subject: Re: Duel LSI ignitions (No mags) |
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Don,
I have a similar situation. Dual LSI, Garmin stack, dual BMA EFIS, AFS engine monitor, IO 360, all electric aircraft.
I opted for two totally independent electrical systems but with the ability to tie them together. B&C 60 as primary, B&C20 on the vacuum pad. LSI’s directly to the batteries through guarded toggle switches. Radios, EFIS, lights, etc split between the two systems.
I have a CAD (.dxf or .fcw) drawing I would be glad to share if anyone is interested.
Roger
RV-7 nearing completion
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mlas(at)cox.net
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| Posted: Wed Nov 22, 2006 7:16 am Post subject: Duel LSI ignitions (No mags) |
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Don,
I have been running dual LSI on my IO-550 powered Lancair Legacy since
Feb. 2006 and have 160 hours on it so far. I also wanted full night and
IFR capabilities. I went with the Z-14, 12 volt system, 80amp primary
alternator, and the 20 amp B&C alternator. The 80 amp main bus runs
most everything and the 20 amp bus runs one ignition, backup EFIS,
autopilot, landing gear indicators, and backup power for dual bus
avionics such as the air data computer, primary EFIS gyro, Nav/Com and
transponder. With everything running on the 20 amp bus I draw about 11
amps and can continue running the airplane in an IFR environment.
I read many post about running lighting on the secondary bus. When you
lose more then half of your power, the last thing you need are lights.
My airplane is setup with 8 busses: Two Ignition Busses 1 left & right,
(wired before the master contactor, so when the ignition switches are on
the ignition system is powered regardless of master switch position.)
Two direct battery busses 1 left & right(for courtesy items such as
cargo light and plug-ins for a GPS or other devices not used in flight,
main busses 1 left & right (all non-avionics systems), Two avionics
busses 1 left and right (all avionics systems). The main busses have a
tie contactor (normally always open/off) to provide additional starting
power and power in the event of an alternator failure on one side. The
avionics busses have a tie (normally always open/off) in the event of a
main bus fault or avionics contactor failure.
If I had to say what the most important aspect of my system is, I would
say having the Ignition system on its own bus allowing it to get power
when all other systems are shut down of fail. In my system you would
have to loose both batteries (less than 5vdc nominal) to loose both
ignition systems.
To date the system has worked flawlessly.
Mike Larkin
Lancair Legacy
TS-11 Iskra
Kitfox IV
A-319/320
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