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  #71  
Old 12-13-2012, 07:01 AM
humptybump humptybump is offline
 
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Walt, don't worry about the technology in your panel. The world is scheduled to end in 9 days and Brian won't get a chance to fly his new panel.

Brian's new panel is sure to be wonderful.

Mike - like you, I'm going the "upgradable panel" path.

This thread is both a good and fun read!
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  #72  
Old 12-14-2012, 07:27 AM
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Brantel Brantel is offline
 
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Here is the proposed wiring diagram for my backup/aux power system:

click for big version:



The backup battery will get charged anytime the master is on. The typical startup work flow will be to close the Aux Battery feed switch first thing to get the EFIS and EMS up and running before start. This switch will remain on till shutdown.

Charge current is limited by the 10ohm 20W resistor. The VP-X Pro takes care of monitoring the backup batteries voltage level.

Distributed over-current protection is provided by both inline fuses and the 6 fuse block.

The Schottky diodes take care of ensuring current flow in the correct directions and to power up the Gemini which does not have a built in backup power pin. The G3X system has backup power pins.

I ended up ordering this battery from BatteryMart.com:



They had hundreds of good reviews on this battery and I have ordered from them before with good service. This appears to be a high volume battery for them so hopefully I will get a fresh one....
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---------------------------------------------------------------------
RV-7/TU, #72823, N159SB
Lyc. O-360 carbed, HARTZELL BA CS Prop, Dual P-MAGs, Dual Garmin G3X Touch
Track N159SB (KK4LIF)
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  #73  
Old 12-14-2012, 09:32 AM
humptybump humptybump is offline
 
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Doing some quick math (often a dangerous thing) ...

The 10 ohm resistor in your charging circuit is pretty large. According to an EE I consulted for the same topic, here is what I got ...

Quote:
Va = alternator voltage
Vb = minimum battery voltage at discharge
Ic = desired charge current

then you have R = (Va-Vb) / Ic

So if your alternator outputs, say, 14.8 volts and the battery has discharged to 11.8 volts and you want a maximum of 2 amps charge current, 14.8-11.8=3, 3/2=1.5, so you'd need a 1.5 ohm resistor.

If you were to actually start a charge from the maximum discharge voltage on the battery, you'd be dissipating 6+ watts in this configuration until the battery voltage starts coming up.

As the battery voltage comes up, of course, the change current drops off until it reaches essentially zero when the battery equals the alternator output.
If I use your 10 ohm resistor, as assume a backup battery below usable voltage - say 4.8V - I get the following ...

10 = (Va-Vb) / Ic
10 = (14.8 - 4.8) / Ic
10 = 10 / Ic

Your Ic (charge current) is 1A.

Last edited by humptybump : 12-14-2012 at 10:50 AM.
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  #74  
Old 12-14-2012, 10:05 AM
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Brantel Brantel is offline
 
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Quote:
Originally Posted by humptybump View Post
Doing some quick math (often a dangerous thing) ...

The 10 ohm resistor in your charging circuit is pretty large. According to an EE I consulted for the same topic, here is what I got ...



If I use your 10 ohm resistor, as assume a backup battery below usable voltage - say 4.8V - I get the following ...

10 = (Va-Vb) / Ic
10 = (14.8 - 4.8) / Ic

Your charge current is 1A.
Glen,

You are correct, and it is that way on purpose. The charge circuit is intended to be a trickle charge only with a slow charge rate.

This is the way I want it for a couple reasons:

1. These type of batteries typically require a pretty slow charge rate to last very long and to not overheat.

2. In the event that I accidently run this battery all the way down, this resistor becomes the only limiter to the current since the internal resistance of these types of batteries is like .025 ohms. This current limit resistor will keep the battery from overheating and or blowing the charge circuit fuse.

Since most of the time this battery may only get used for a few minutes during startup, most flights it will have plenty of time to stay charged up fully.

Be cautious around EE's, they are strange people!!!
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Brantel (Brian Chesteen),
Check out my RV-10 builder's BLOG
RV-10, #41942, N?????, Project Sold
---------------------------------------------------------------------
RV-7/TU, #72823, N159SB
Lyc. O-360 carbed, HARTZELL BA CS Prop, Dual P-MAGs, Dual Garmin G3X Touch
Track N159SB (KK4LIF)
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Last edited by Brantel : 12-14-2012 at 10:16 PM.
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  #75  
Old 12-14-2012, 10:23 AM
morganjp morganjp is offline
 
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Question:

Will having the alternate battery being recharged any time the master is on shorten the battery life? When we updated my panel we put the alternate battery on a breaker to the avionics bus only. That way I can get the atis info and program the 396 and 430 off the alternate battery without the master being on. After starting the engine I then turn on the avionics master and rechage the alternate battery until I get my first 396 advisory to switch fuel tanks at thirty minutes into the flight. Then I turn off the breaker to the alternate battery until the next flight. It doesn't make sense to me to have the alternate battery controlled by the master breaker and having both batteries discharging at the same time.

Just my 2 cents.

John Morgan
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  #76  
Old 12-14-2012, 10:28 AM
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Brantel Brantel is offline
 
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I want to get all the heavy cutting, grinding, drilling, etc. out of the way before the avionics even come out of the box. Then do a good vacum job on the interior to get rid of the mess I have made.

So last night I started working on the panel support ribbs.

The old panel support had three ribs. Two on the pilot side that were riveted in non-standard locations and one factory one on the co-pilot side.

I had to drill out the one on the left and the one on the center and then cut the one off on the right. I also drilled out all the rivets for the old map box braces.



Here it is all clean and full of holes like swiss cheese!



So then I discarded the pilot side one and added a new piece of angle to the one I cut off from the co-pilot side and re-mounted it to the pilot side. I moved the center one to the co-pilot side. The new panel will not have a third one. I used the Red panel to locate and drill the new locations for the ribs. Keep in mind that this Red panel is now a mock-up only panel because I do not like the Red color mismatch with the fuse. I have a new Grey one being built that will become the final panel.





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Brantel (Brian Chesteen),
Check out my RV-10 builder's BLOG
RV-10, #41942, N?????, Project Sold
---------------------------------------------------------------------
RV-7/TU, #72823, N159SB
Lyc. O-360 carbed, HARTZELL BA CS Prop, Dual P-MAGs, Dual Garmin G3X Touch
Track N159SB (KK4LIF)
Like EAA Chapter 1494 on Facebook
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  #77  
Old 12-14-2012, 10:47 AM
humptybump humptybump is offline
 
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Brian,

One thing I am curious how you solved is the back support for the radio stack. Do you have a direct supporting connection at the back of your radio stack and if so, how is it fastened ?

In my case, I want my panel to be easily removable. The radio stack back "support connection" is what I have not figure out yet.
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  #78  
Old 12-14-2012, 10:54 AM
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Brantel Brantel is offline
 
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Quote:
Originally Posted by humptybump View Post
Brian,

One thing I am curious how you solved is the back support for the radio stack. Do you have a direct supporting connection at the back of your radio stack and if so, how is it fastened ?

In my case, I want my panel to be easily removable. The radio stack back "support connection" is what I have not figure out yet.
Not yet but I know what I want to do. I will have an angle fastened to the sub panel horizontally creating a shelf for the trays. I will also make two vertical ones on the sub panel that are removable for the sides and the trays will get a screw thru the side into them.
__________________
Brantel (Brian Chesteen),
Check out my RV-10 builder's BLOG
RV-10, #41942, N?????, Project Sold
---------------------------------------------------------------------
RV-7/TU, #72823, N159SB
Lyc. O-360 carbed, HARTZELL BA CS Prop, Dual P-MAGs, Dual Garmin G3X Touch
Track N159SB (KK4LIF)
Like EAA Chapter 1494 on Facebook
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  #79  
Old 12-14-2012, 01:22 PM
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Brantel Brantel is offline
 
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Quote:
Originally Posted by morganjp View Post
Question:

Will having the alternate battery being recharged any time the master is on shorten the battery life? When we updated my panel we put the alternate battery on a breaker to the avionics bus only. That way I can get the atis info and program the 396 and 430 off the alternate battery without the master being on. After starting the engine I then turn on the avionics master and rechage the alternate battery until I get my first 396 advisory to switch fuel tanks at thirty minutes into the flight. Then I turn off the breaker to the alternate battery until the next flight. It doesn't make sense to me to have the alternate battery controlled by the master breaker and having both batteries discharging at the same time.

Just my 2 cents.

John Morgan
John,

No it does not and as far as that goes, most UPS's and alarm systems have these types of batteries and while the power is on, they are being charged.

But being charged is kinda bad terminology....current will only flow into the battery when the battery's voltage is less than that of the voltage being applied to it. So if you apply a constant voltage to the battery, it will self regulate it's charge current down to the point where little if any current is flowing as long as the battery is capable of reaching a voltage that is close or equal to the applied voltage.

Such is the case with my planned circuit. The applied voltage when the master is on and the alternator is running will always be one Schottky diode drop below the voltage regulator output or somewhere around 13.8 volts which is right at the top of the recommended float charge voltage of this battery....

There are batteries out there that need constant current charging and that is a completely different animal.


"It doesn't make sense to me to have the alternate battery controlled by the master breaker and having both batteries discharging at the same time."

The reason this does not make sense to you is because that is not the way it all works. The load will only pull current from the supply with the highest voltage because the two power inputs are fed thru two back to back diodes....

The Aux battery is not controlled by the master relay, only charged by it. The Aux battery bus has it's own switch that comes on before start and stays on until shutdown. The Aux battery only provides current to the critical loads during startup until the engine is running with the alternator on and the avionics master is turned on. From that point the critical loads will source their current from their primary feeds thru the VP-X Pro unless the main battery and the alternator dies and in that case, the backup battery will start providing current to the critical loads.
__________________
Brantel (Brian Chesteen),
Check out my RV-10 builder's BLOG
RV-10, #41942, N?????, Project Sold
---------------------------------------------------------------------
RV-7/TU, #72823, N159SB
Lyc. O-360 carbed, HARTZELL BA CS Prop, Dual P-MAGs, Dual Garmin G3X Touch
Track N159SB (KK4LIF)
Like EAA Chapter 1494 on Facebook

Last edited by Brantel : 12-14-2012 at 09:47 PM.
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  #80  
Old 12-15-2012, 07:05 PM
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Brantel Brantel is offline
 
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First thing today was cleanup and cleanout time of the cockpit. I pulled up the carpet and cleaned all the wires, connectors, tools, screws, washers, nuts, bolts, parts etc. etc. etc. out of the airplane. It was a complete mess. I got it all cleaned up and moved on to making more of a mess....

First thing today was to remove the canopy. I hate putting it at risk but it just had to be done. My buddy that helped me who is also an RV builder and I both commented on how crazy I was for even messing with the canopy let alone taking it off and laying it in the floor. Hopefully it won't get damaged during the process.



Looks weird but it really opens up the work space. I needed to do some work on the seal in the front. The work I needed to do could not be done with the canopy on there. Bonus is that it is out of my way....
Got out the Dremel and did the cuts of the seal shelf that I needed to do. If I were building another tipup RV, this area would be built very much differently!!!!



Fabricating a new angle to go along the bottom of the panel.



All drilled in place.



Some reliefs need to be cut to make room for components of the panel.



Mark em and provide some relief.



All the reliefs cut out and blended.



Shot from behind....



Drilled out all the rivets holding this angle to the old panel. Not about to remake that thing again!!!



All removed and ready to fit to the new panel.

__________________
Brantel (Brian Chesteen),
Check out my RV-10 builder's BLOG
RV-10, #41942, N?????, Project Sold
---------------------------------------------------------------------
RV-7/TU, #72823, N159SB
Lyc. O-360 carbed, HARTZELL BA CS Prop, Dual P-MAGs, Dual Garmin G3X Touch
Track N159SB (KK4LIF)
Like EAA Chapter 1494 on Facebook

Last edited by Brantel : 12-15-2012 at 07:13 PM.
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