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Dual Batt Diagram needed

Guilhermepilot

Guilhermepilot

Well Known Member
Does Someone have a good diagram
For dual pc680 batt one alternator single
G3X GTR200 GTX 327?
I would like to have a dedicated batt for avionics
during start

Thanks in advance
 
I'm not sure why you want a dedicated avionics battery for start. If you insist on having one, I'd sure consider a much lighter/smaller battery for the avionics.
 
I also would just go with a lightweight battery for the avionics buss for start-up. I have dual PC-680's in my -10 with dual masters. Even with both masters on and the avionics booted up, there is enough draw to turn most the avionics off when I crank the engine.
 
Guilherme,

I'm trying to figure out that same thing at the moment. Well almost. I did plan on having a aux alternator. Do a search of VAF and you will find most of what you want. If you don't want a second alternator like I do it is simpler. You can look at the Z-14 aeroelectric page that has 2 batts and 2 alternators as a start. There are also some references that show you how to use a couple of diodes to do the isolation.

I was trying to figure out my panel layout and then I realized I needed to figure out more of my electrical system before I could finish the panel.

Basically the idea is to have a separte Aux Batt power switch to enable your startup instruments. The Aux Batt bus can be powered by the Main bus through a high current diode. Th Aux Batt is then charged by the Main bus through a diode and series resistor for current limiting. Once the Main power switch is turned on it should then supply the devices instead of the Aux battery. There are lots of variations on this scheme so I'm trying to figure out exactly what I want. I couldn't find a schematic that has everything that I want so I think I'll have to start drawing my own.
 
IBBS

I'm using the IBBS battery http://www.tcwtech.com/IBBS.htm

For my G3X essentials bus.

I have not started my engine yet (2 weeks:rolleyes: from now)
but my VP-X is showing the G3X only pulling 1-2 amps (2 screens and ADHR)

At that rate the 4amp/hr (6 amp max) should last over 2 hrs with just the G3X in an emergency. Definitely fine for starting.
 
Bill

I'd say your estimates are a little on the optomistic side. I just looked the currents up today in the G3X I installation manual. Each screen 370 & 375 are sped'd at 1.1 Amps max plus the current for the other boxes like the GEA24. Granted typical numbers are probably less. Remember that the max current drain of the battery in amperes is different than the battery capacity ampere-hours. The capacity is the current drain times the duration hours at a rated current. So for backup purposes where I would want to be conservative you have less than 2 hours of backup time give 4 A-H divided by 2.2 amperes for the two screens alone.

This approach is conservative I admit but I do think it's important for these backup applications that everyone understand the correct way to do these calculations. The amount of actual battery life available for an emergency situation is up to each builder. Just my 2 cents as Stein says. Everyone can do their own thing and will I'm sure but my backup is going to based on worst case numbers.
 
Here is a link to Bob Nuckolls' designs (free download): http://www.aeroelectric.com/PPS/Adobe_Architecture_Pdfs/
Z-10/8A 1 & 2 has a brownout battery. Just erase or ignore the dynamo circuit at the top of the drawing. I have done that in this modified version: https://drive.google.com/file/d/0B7ZTG2VpCuDRdzlRS2YxQUtpc0k/edit?usp=sharing
Here is another circuit that I drew: https://drive.google.com/file/d/0B7ZTG2VpCuDRVWYzM3JQYy1mNkk/edit?usp=sharing if it is desired to isolate the two batteries.
Joe Gores
 
Basic Backup/Brownout System

This design is derived from Bob Nuckolls's work. In some ways even simpler.
1zqg5s0.jpg
1zqg5s0.jpg
1zqg5s0.jpg
1zqg5s0.jpg
 
Yes is very complex, I think have an avionics health at starts
And during eletrical fault is the way thanks for your input
Here in Brazil we do not have odyssey and import is a problem due to dangerous cargo policies but I found a battery caled moura it has 12v 18 amps, it is for boat but I think will fit well dimensions is the same

Thanks

rapid_ascent said:
Guilherme,

I'm trying to figure out that same thing at the moment. Well almost. I did plan on having a aux alternator. Do a search of VAF and you will find most of what you want. If you don't want a second alternator like I do it is simpler. You can look at the Z-14 aeroelectric page that has 2 batts and 2 alternators as a start. There are also some references that show you how to use a couple of diodes to do the isolation.

I was trying to figure out my panel layout and then I realized I needed to figure out more of my electrical system before I could finish the panel.

Basically the idea is to have a separte Aux Batt power switch to enable your startup instruments. The Aux Batt bus can be powered by the Main bus through a high current diode. Th Aux Batt is then charged by the Main bus through a diode and series resistor for current limiting. Once the Main power switch is turned on it should then supply the devices instead of the Aux battery. There are lots of variations on this scheme so I'm trying to figure out exactly what I want. I couldn't find a schematic that has everything that I want so I think I'll have to start drawing my own.
Click to expand...
 
There has been a discussion on Bob Nuckolls' AeroElectric list concerning a series resistor in the aux battery charging circuit. http://forums.matronics.com/viewtopic.php?p=316578
K1 Aircraft Electrical System is a nice simple circuit. Relays controlled by the E-Bus switch could be located at one or both batteries while still making it simple for the pilot to operate. The advantage of relays is the ability to shut off power at the source in case of smoke in the cockpit or imminent forced landing.
Joe Gores
 
An lightweight alternative to a brownout battery is a DC-DC converter used to boost the voltage to avionics during engine cranking. DC-DC converters are available on eBay at low cost from China. The claimed ampacity is exaggerated. So it is better to buy one rated at 2 or 3 times the expected load.
Joe Gores
 
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