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  #11  
Old 05-03-2018, 05:35 PM
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Walt Walt is offline
 
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Small backup batteries cannot accept a high current charge, if you use a battery that can accept the full alternator output then you need to size wires, relays, diodes, etc. appropriately.
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  #12  
Old 05-03-2018, 05:36 PM
GeraldC GeraldC is offline
 
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Quote:
Originally Posted by ssonixx View Post
Do I have this right?
Dan is right. Ignore all of your schematic except for the main battery, the E-bus relay, and the start enable switch. Ignore the master solenoid completely.
Then draw the E-bus relay with the relay closed instead of opened, which is how it will be when you turn off the master switch. You've pretty much designed a latching relay.
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  #13  
Old 05-03-2018, 05:39 PM
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Actually Joe designed it, but yep, it's latched, unless the shutdown procedure includes cycling the start enable.

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  #14  
Old 05-03-2018, 07:34 PM
ssonixx ssonixx is online now
 
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Understood. Thank you.

Quote:
Originally Posted by Walt View Post
Small backup batteries cannot accept a high current charge, if you use a battery that can accept the full alternator output then you need to size wires, relays, diodes, etc. appropriately.
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  #15  
Old 05-03-2018, 07:36 PM
ssonixx ssonixx is online now
 
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Got it! Thank you for your effort to draw this. I would never have seen this.

Quote:
Originally Posted by DanH View Post
Actually Joe designed it, but yep, it's latched, unless the shutdown procedure includes cycling the start enable.

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  #16  
Old 05-03-2018, 09:24 PM
Mich48041 Mich48041 is offline
 
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Location: Riley TWP MI
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I modified my drawing so that the E-Bus relay can be turned on regardless of the battery contactor state.
I like to think of the switch as an E-Bus switch, not as a start enable switch. The E-Bus switch must be off
in order to start the engine. Yes, leaving the E-Bus switch on will run the battery down same as if the
master switch is left on. Bob N. has his E-Bus connected the same way. Mount the Master switch and E-Bus
switch and aux battery switch next to each other and shut all off simultaneously.
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  #17  
Old 05-04-2018, 03:54 PM
bjohnson1234 bjohnson1234 is offline
 
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Quote:
Originally Posted by Mich48041 View Post
I modified my drawing so that the E-Bus relay can be turned on regardless of the battery contactor state.
I like to think of the switch as an E-Bus switch, not as a start enable switch. The E-Bus switch must be off
in order to start the engine. Yes, leaving the E-Bus switch on will run the battery down same as if the
master switch is left on. Bob N. has his E-Bus connected the same way. Mount the Master switch and E-Bus
switch and aux battery switch next to each other and shut all off simultaneously.
what software are you using to create these diagrams?
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  #18  
Old 05-04-2018, 05:22 PM
Mich48041 Mich48041 is offline
 
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Location: Riley TWP MI
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Sometimes I use AutoCad and sometimes Express.sch
AutoCad is not intuitive. Even after getting proficient at using it, it is easily forgotten.
After not using AutoCad for a year, it was frustrating trying to re-learn it.
Express.sch is free and a WHOLE lot easier to learn and use.
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  #19  
Old 05-04-2018, 07:11 PM
jump4way jump4way is offline
 
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Quote:
Originally Posted by Walt View Post
Small backup batteries cannot accept a high current charge, if you use a battery that can accept the full alternator output then you need to size wires, relays, diodes, etc. appropriately.
To Walt?s point, what in Joe?s diagram protects the small backup battery from high alternator charge current?
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  #20  
Old 05-04-2018, 07:23 PM
moosepileit moosepileit is offline
 
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Don't you just use a resistor on the feed from the main bus to the small battery after a diode so the small battery cannot power the main bus? Allows about 1/3 of the amp-hour rating of the small battery to charge the small battery? 1 have 1 AH SLA that gets 300 milliamps via a 50 ohm resistor. Even with a schotky diode with low forward loss, it never exceeds 13.8 volts in flight. V=IR.

My small battery is only for brownout protection at engine start of a GRT EFIS and Trutrak Gemini PFD. The Gemini has two input paths, both with diodes allowing power only in from the small battery or the essential bus, whichever has higher voltage. The GRT has 2 power inputs and internal diodes, 1 the essential bus, the other the small battery.
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