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View Poll Results: What is your electrical setup?
1 batt / 1 alt 28 28.28%
1 batt / 1 alt and yes I fly IFR 11 11.11%
1 batt / 1 alt plus a backup batt (IBBS) not just G5 battery 6 6.06%
1 bat/ 1 alt plus backup (IBBS) and I fly IFR 10 10.10%
1 bat / 2 alt 10 10.10%
1 bat / 2 alt with sd-8 alt (z-13) 3 3.03%
1 bat / 2 alt plus (IBBS) 10 10.10%
1 bat / 2 alt with sd-8 alt (z-13) plus (IBBS) 3 3.03%
2 full sized batt / 1 alt (z-19 or equivalent) 7 7.07%
2 batt / 2 alts (z-14 or equivalant) 11 11.11%
Voters: 99. You may not vote on this poll

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  #11  
Old 03-15-2019, 10:36 PM
Paul 5r4 Paul 5r4 is offline
 
Join Date: Oct 2006
Location: Foley, Al
Posts: 375
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Good timing on this thread. I just now am thinking of converting my VFR only 7A to IFR. I've pretty much decided to go with a second full size battery each with redundant ways to deliver their power to any avionics that need it. I'm with DakotaHawk. If alt quits.... the dynon will have a separate battery.... the Garmin G5 will have an internal battery.... the ifly software on my tablet driven from a stratux receiver will provide a synthetic vision capability. That would be last resort. Remember there is two full size batteries to power the important stuff too. I think I would make it back to the planet with time to spare. I'm not one that would press on! Loss of the alt would prompt me to take action to get back to VFR weather or at the least below the clouds ASAP.
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  #12  
Old 03-16-2019, 04:22 AM
control control is offline
 
Join Date: Feb 2006
Location: Stockholm, Sweden
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I have one alt, one bat and no back-up battery. I consider my AC a strictly VMC machine in this configuration.
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  #13  
Old 03-16-2019, 08:06 AM
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Carl Froehlich Carl Froehlich is offline
 
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As Iíve offered in the past, I will send my dual PC-625 power scheme to anyone interested. Just PM me your email address.

Carl
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  #14  
Old 03-16-2019, 08:47 AM
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GalinHdz GalinHdz is offline
 
Join Date: Mar 2010
Location: KSGJ / TJBQ
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1 battery, 1 alternator and I occasionally fly in IMC.

But have dual self powered P-Mags, dual Skyview, a D6, a Garmin Aera, an Android tablet and a handheld radio all with internal backup batteries. Probably electrical overkill to quickly get me on the ground.



Before you ask, yes I only have 1 engine.
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Last edited by GalinHdz : 03-16-2019 at 08:49 AM.
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  #15  
Old 03-16-2019, 08:57 AM
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N941WR N941WR is offline
 
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As you design redundancy into your electrical systems, be very careful.

The more complexity you add, the more likely it is something will go wrong; either you didn't take something into account with your design, you take the wrong action when SHTF, or a part fails, rendering your entire electrical system useless.

The best system is one that requires no action by the pilot in the event of an electrical failure.

Remember, Bob K's most excellent electrical design book came out before EFIS's were popular or had internal backup batteries. I wonder what he would recommend today. (I haven't looked at his book in Iver 10 years.)

If you install any type of battery backup system, schedule battery replacements every "X" years.

If you have an E-buss or other type of backup system, practice with it and if it isn't what you need, change it.

Best of luck and be safe!
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  #16  
Old 03-16-2019, 09:17 AM
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Carl Froehlich Carl Froehlich is offline
 
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Quote:
Originally Posted by N941WR View Post
SNIP>>>

The best system is one that requires no action by the pilot in the event of an electrical failure.<<<<SNIP
Exactly correct.
Design Objective #1: Continued IFR flight (including comms and XPDR) following an element failure with no pilot action. Electrical failure is not the simple loss of the alternator as this does not result in the immediate loss of any of the panel. The more challenging single failure points are common connections (including grounds), solenoids, switches, the various diode schemes and such.
Design Objective #2: Restoration of the lost panel components following an element failure with minimal pilot action. That action not to impact flying the plane in IMC and factoring in a high pucker factor.

Carl

Carl
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  #17  
Old 03-16-2019, 02:53 PM
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catmandu catmandu is offline
 
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60 amp alternator, PC680, worst case 7.5 Ah alarm battery to give me 30 plus minutes of avionics buss to get out of the clouds. Diodes make it all work effortlessly.

And an alternator on the pmag, but I donít count that really.
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  #18  
Old Yesterday, 12:09 PM
Paul 5r4 Paul 5r4 is offline
 
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I've received Carl's schematic for dual batteries and he's reinforced to me via emails the importance of being able to get that power to the critical places with no to minimal pilot action. I absolutely agree with the previous post about making your system too complex. That in itself adds a degree of increased risk.

Here's my thinking. I'll have two batteries and one alt. If I have an alt failure, I would be notified of that by the Dynon EMS. If I confirm/agree with the EMS of an alt failure, all I have to do is flip the two switchs to get power from BOTH batteries directly to the avionics and turn off the master switch. Power from the batteries will be direct to the avionics with the only connections being 1. At the battery 2. The relay (power in and power out) 3. The avionics buss connection.

With the Dynon's back up battery and the built in G5 battery along with the two full size batteries up front, I feel this would give me best I can figure an absolute minimum of like 90 minutes to get back to VFR or below the clouds.

Discussion: Carl's stresses the importance of getting the power to the necessary equipment. I agree. That includes battery grounds. Each of my batteries will be grounded side by side to the airframe/engine block.
A thought on the relays that will be the only thing inline between the batt power and avionics buss. The connection for power in and power out of each relay from each battery to the buss. There is of course the wires running into the cockpit for the switch and switch to ground that could fail too.... as well as the switch itself. Here again, There is ANOTHER switch going through the other relay to provide power from the other battery directly to the buss. OK..... What are the odds of first an alt failure followed by a second failure of a relay/switch/wiring connection at the same time and if that WERE to happen, there is the second battery with the exact same setup to get power from that OTHER battery to the buss? Admittedly I'm just learning all this stuff and am speaking from probably the most inexperienced point of view on VAF.

Reviewing my own schematic, I see there's a single point of failure at the 25 amp pull breaker. If that did happened it would only make sense to turn off both "direct to" relay switches again and go back to the battery only side of master to get power to the avionics buss. I wonder if it would make sense to leave the batt side of master on from the beginning of the alt failure and turn on the two "direct" source switches. Of course this last would add the importance of sheding all unnecessary loads from the main. The advantage is now there are THREE ways power is getting from the batteries to the avionics buss.

Any thoughts are appreciated.
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Last edited by Paul 5r4 : Yesterday at 01:57 PM.
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  #19  
Old Yesterday, 02:25 PM
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Carl Froehlich Carl Froehlich is offline
 
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Paul,

Good process, now take it a step further. Consider a fault on the avionics buss itself. You loose everything.

Run half of your panel on each battery by having two avionics busses. As you'll note in the material I sent you having four small 30 amp avionics relays provides option to have a normal and backup source of power for each avionics buss. Last step is to delete the avionics master switch you have that ties the avionics buss to the main buss.

On any electrical fault first immediate action is to open both master solenoids - this places panel power in the most reliable state. Once stable, then decide if you want to trouble shoot stuff or just fly the 2+ hours on the reserve electrical capacity and figure it out on the ground.

Carl
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  #20  
Old Yesterday, 07:37 PM
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maniago maniago is offline
 
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I didnt vote cause I'm not RV, but I'm fully Z14 architecture (some minor mods wrt switches) and a Mini-X with back up batt. I'll prob use an Ipad with FlyQ for non panel maps and planning etc. Gear list in my sig block. IFR.
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Last edited by maniago : Yesterday at 07:42 PM.
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