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  #21  
Old 05-03-2020, 09:27 AM
supik supik is offline
 
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Location: Bratislava, Slovakia
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Quote:
Originally Posted by Carl Froehlich View Post
Some thoughts:
- If your battery is flat, this is a hard “ground the airplane” issue. Use a real charger to bring it back, or better yet replace it as most AGM batteries suffer permanent capacity loss if you abuse it (e.g. leave the master on).
You are right, bad wording from my side. I meant the situation when for some reason the battery was discharged in flight (wrong procedures etc).

Quote:
Originally Posted by Carl Froehlich View Post
- I suggest you eliminate the ground power jump connection. This is a left over from vacuum driven gyros and mags. In other words, never jump start your airplane. You will be launching into the ether with no clue of battery capacity, if any. On top of that, these are massively clumkly plugs with big fat wires - both are on the list of things to minimize in our airplane.
Already installed very close to the battery for the purpose of ground maintenance, avionics setup and battery recharge.

Quote:
Originally Posted by Carl Froehlich View Post
- On loads for each alternator, you will need to carefully adjust each voltage regulator to make sure you have current flowing as you think you do (for each of your primary and back up modes). Adding diodes complicates this as voltage drop across the diode needs to be measured to achieve the load balance you want.
Normal ops is: both ESS(ESS Contactor) + ALT2 and MASTER (BATTERY Contactor) + ALT1 ON.
Normal current flow is expected to pass through the contactors and 'avoid' the Schottky Diode with voltage drop. Only in case the BATTERY Contactor fails open, current starts flowing through the diode from MAIN BUS to ESS BUS. Correct me if wrong.

Quote:
Originally Posted by Carl Froehlich View Post
- On loads for each alternator, you will need to carefully adjust each voltage regulator to make sure you have current flowing as you think you do (for each of your primary and back up modes). Adding diodes complicates this as voltage drop across the diode needs to be measured to achieve the load balance you want.
ALT 1 reg. is set to 14.4V
ALT 2 at 13.8V
-With both ALTs ON, ALT2 should take over as soon as Voltage drops to 13.8V sensed at the ESS BUS
-Regulators sense their respective bus they are feeding. In case ALT 2 failed, ALT 1 output won't be effected by the voltage drop across the diode to ESS BUS.
Should ALT 1 fail, ALT 2 can still feed both the ESS and MAIN BUS as long as both contactors are closed and load shedding performed by pilot.

Quote:
Originally Posted by Carl Froehlich View Post
Note however that 60 amp alternators will put out more than 60 amps, so upsize your current limiter to 70 amps. But again if you are trying to use the alternator to breath life into a dead battery, you are violating a prime rule as discussed above.
- On my planes I do add a “shore power” breaker to the main buss. I use this to connect my 30 amp regulated power supply using a short #14 jumper cable to run the plane on the ground. 30 amps is more than enough to run the whole panel and to keep the batteries topped off (just like the alternator does). In practice with both (charged) batteries on line and all avionics up - current draw is about 10 amps.

Carl
B&C 60Amp Alternator install manual says to use a 70amp CB or 60amp ANL, I'm going with the ANL.

I'll have a look at the shore power breakers.

Thank you for your comments.
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Last edited by supik : 05-03-2020 at 09:56 AM.
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  #22  
Old 05-03-2020, 09:27 AM
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Walt Walt is offline
 
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Why build such a simple aircraft with such a complicated electrical system?

5 busses, multiple relays, high current diodes etc., is it really necessary or is it just fun to work on the designs?
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  #23  
Old 05-04-2020, 03:39 PM
supik supik is offline
 
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Quote:
Originally Posted by Walt View Post
Why build such a simple aircraft with such a complicated electrical system?

5 busses, multiple relays, high current diodes etc., is it really necessary or is it just fun to work on the designs?
I could eliminate the avionics buses but it allows me to perform load shedding if I need to (ALT 1 failure / ground ops/flight preparation with engine out / engine start without additional draw from avionics on cold days)

The diode between MAIN BUS and ESS BUS is there for redundancy. I'm planing IFR+night ops.
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  #24  
Old 05-06-2020, 03:48 PM
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MCA MCA is offline
 
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I have to agree with Walt on this one. In the quest for redundancy, you'll likely get lower reliability and tricky troubleshooting in the future.

The great think about Exp aircraft is we can build what we want!
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  #25  
Old 06-07-2020, 04:08 PM
supik supik is offline
 
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Location: Bratislava, Slovakia
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Default Version 32

Thank you all for your comments, version 32 is alive -I had a look, it's still way simpler than Cirrus


https://i.ibb.co/6twfYhp/Diagram-OM-...v-032-200p.jpg

PDF: Diagram-OM-ELA-Igor-v-032 PDF


-do you see any mistakes? omissions? flaws?
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Last edited by supik : 06-07-2020 at 04:27 PM. Reason: PDF added
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  #26  
Old 06-07-2020, 08:14 PM
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johnbright johnbright is offline
 
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Default magneto switch options

Hi Egor,

Have you seen Bob Nuckolls' document called "Magneto Switch Options"? Some important differences from what you show.

http://www.aeroelectric.com/articles...tchOptions.pdf

I see the v32 jpg but not the pdf.
.
.
.
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  #27  
Old 06-07-2020, 08:16 PM
Mich48041 Mich48041 is online now
 
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Replace the 40 amp ANL alternator fuse with a 35 amp and move it close to
the E-Bus. The alternator does not need protection, the E-Bus does.
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  #28  
Old 06-08-2020, 03:00 AM
supik supik is offline
 
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Quote:
Originally Posted by johnbright View Post
Hi Egor,

Have you seen Bob Nuckolls' document called "Magneto Switch Options"? Some important differences from what you show.

http://www.aeroelectric.com/articles...tchOptions.pdf

I see the v32 jpg but not the pdf.
.
.
.
John,

I think I have the same setup as suggested by Bob N. unless I missed something? -except the Right Mag is not grounded (Left Mag (SureFly) is not impulse coupled). And I have omitted the BO pole by mistake but this one is not connected to anything either.

New PDF link: OM ELA Basic Electr Scheme v.32

Here is another guide from B&C which corresponds to Bob's setup + MOV across the S pole. https://bandc.com/wp-content/uploads...501-3_fig4.pdf
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  #29  
Old 06-08-2020, 04:39 AM
supik supik is offline
 
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Quote:
Originally Posted by Mich48041 View Post
Replace the 40 amp ANL alternator fuse with a 35 amp and move it close to
the E-Bus. The alternator does not need protection, the E-Bus does.
Joe,

I'm a little bit puzzled with this. B&C recommends the 40amp ANL for the backup alternator. I understand it's not going to put out more than 32amps untill I go above 2700rpm on the engine. So, yes 35 seems to be sufficient but will it make any difference?

You are right about protecting the ESS BUS:

-if ANL placed on the engine side of firewall:
  1. (condition: short is developed in the alternator), the ANL will protect rest of the wire leading through the firewall to the ESS BUS. Firewall feed through remains hot from ESS BUS.
  2. (condition: alternator has no fault but wire makes contact with firewall) - no protection to ESS BUS until ESS BUS is isolated. (ESS Switch to OFF)

-if ANL placed on the cockpit side of firewall:
  1. (condition: short is developed in the alternator), the ANL will protect the wire leading from the ANL to the ESS BUS.
  2. (condition: alternator has no fault but wire makes contact with firewall), ESS BUS is protected but short will be present until ALT 2 is turned OFF (ESS Switch to ESS BUS only)

Both variants IF specific faults develop require pilot action, but cockpit side protection will allow for ESS BUS to remain available.

So yes, I'm now leaning towards placing the ANL on the cockpit side of FW - thoughts?
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Last edited by supik : 06-08-2020 at 04:45 AM.
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  #30  
Old 06-08-2020, 08:08 AM
Mich48041 Mich48041 is online now
 
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The aux alternator "B" lead definitely needs to be protected between the E-Bus and
the firewall. If that wire shorts to the firewall, battery current will cause smoke or fire.
Take a look at an ANL data sheet. A 35 AMP ANL will carry 80 amps indefinitely without
blowing. How many amps will the E-Bus normally draw? I think that a 35 AMP is adequate.
Isn't the E-Bus switch normally shut off and E-Bus current flows through the diode?
What happens if the "B" lead shorts out? Does the 50 amp circuit breaker trip
before the ANL blows? Or does the diode smoke? Do any of Bob N's diagrams
have the aux alternator connected directly to the E-Bus?
There are 3 unnecessary points of possible failure between the E-Bus and the avionics bus:
a 20 amp breaker, a switch, and a relay. Why not eliminate the avionics bus
and power the avionics from the E-Bus?
Why have a 50 amp breaker? The E-Bus is not going to short out if properly installed.
Since the E-Bus is essential, eliminate unnecessary points of failure.
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