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12-31-2009, 08:29 PM
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Join Date: Jan 2005
Location: Columbia, SC
Posts: 804
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Multiple solutions ...
Quote:
Originally Posted by jjconstant
Hi All
I have my plane wired up with 2 PC680 batteries. I start the engine on both batteries. Problem is, my GRT Horizon 1 dual screens come on with the master but the starting voltage sag causes them to reboot. Is this bad for them...do I need to install a switch or switches and keep them off until after starting? I didn't think with 2 batteries the starting current draw would still reboot the systems, but...
Jeremy
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Having been down this path I would suggest getting a THIRD battery of at least 7.5AH capacity and feed that to the third voltage input. Fuse as appropriate and route through a switch. Feed the third one for charging via appropriate diode setup OR just purchase backup battery module from GRT.
At engine start, the voltage drops a LOT more than most people probably realize. It does not take much to keep the the GRT alive but if the voltage goes below 8V they are going to check out. Even a small 9v battery would keep them alive but you will want something you can charge AND something that keeps them going for a few minutes even if all the big stuff fails.
Another reason for doing it this way is that you can just switch on the GRT's and NOT have to turn on the master and drain your main batteries when you want to check things out on the ground.
James
__________________
James E. Clark
Columbia, SC
RV6 Flying, RV6A Cowling
APRS
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01-01-2010, 06:28 AM
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Join Date: Apr 2008
Location: Webster, MN
Posts: 94
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Intelligant Power Stabilizer
TCW Technologies makes a product called an Intelligent Power Stabilizer that will keep the power at 11.25 VDC or greater with input voltages as low as 5 VDC. The power drop and EFIS re-boots is exactly what this unit was designed for and can provide up to 8A output for that short time. That would even run a Garmin G900X. The largest system weights 14 oz, much less than a battery.
Christer
SteinAir Inc.
A&P, Avionics Tech
Cessna 120, RV-8 under construction
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01-01-2010, 06:57 AM
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Join Date: May 2005
Posts: 502
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Back up battery and charging
A couple of mentions about the back up battery on the GRT EFIS but no details on the charging circuit. Is it simply wired to the main bus with a diode or is it more complex than this? I've been meaning to add this to my GRT Sport and need to get after it.
Always appreciate the input.
__________________
Carl Raichle
Lutz, FL
RV-9A N194CR
RV-14A Under construction
Based at KZPH
AA4SR
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01-01-2010, 08:00 AM
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VAF Moderator / Line Boy
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Join Date: Jan 2005
Location: Dayton, NV
Posts: 12,256
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Quote:
Originally Posted by carlrai
A couple of mentions about the back up battery on the GRT EFIS but no details on the charging circuit. Is it simply wired to the main bus with a diode or is it more complex than this? I've been meaning to add this to my GRT Sport and need to get after it.
Always appreciate the input.
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Mine comes off the battery bus with a diode and resistor (to limit current in case of a problem). Also have a circuit breaker/fuse in there for safety. It charges anytime the smaller battery is at a lowr potential than the main battery bus. I put in a new 5 Ah Aux battery about every two years.
Paul
__________________
Paul F. Dye
Editor at Large - KITPLANES Magazine
RV-8 - N188PD - "Valkyrie"
RV-6 (By Marriage) - N164MS - "Mikey"
RV-3B - N13PL - "Tsamsiyu"
A&P, EAA Tech Counselor/Flight Advisor
Dayton Valley Airpark (A34)
http://Ironflight.com
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01-01-2010, 10:30 AM
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Join Date: Jan 2005
Location: Columbia, SC
Posts: 804
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Ditto Paul's comment plus ...
Quote:
Originally Posted by Ironflight
Mine comes off the battery bus with a diode and resistor (to limit current in case of a problem). Also have a circuit breaker/fuse in there for safety. It charges anytime the smaller battery is at a lowr potential than the main battery bus. I put in a new 5 Ah Aux battery about every two years.
Paul
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You can do it this way **OR** you can now get a setup from GRT. Last time I chatted with them, they were using a battery smaller than I wanted to I put the circuit onto a larger battery. There is a "sense" wire that you can connect to the Horizon and display a **sort of** battery charging status. It works as advertised but we agreed it could be improved on the "user interface" side.
James
__________________
James E. Clark
Columbia, SC
RV6 Flying, RV6A Cowling
APRS
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01-01-2010, 10:55 AM
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Join Date: Sep 2006
Location: Bozeman, Montana
Posts: 858
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Questions
Here is the wiring chart for the GRT Back-up battery, which I find a little obtuse. Do you use just one for all your EFIS's (EFII?), or one each? Should the aux battery pull power off the main or avionics bus? When you say battery bus Paul, is that the same as the main bus? NASA nomenclature? Do you then just run with the aux battery on, or do yo shut it off after startup?
I have questions about using the Intelligent Power Stabilizer too. The wiring diagram for it shows it feeding off the main bus. So this means that each unit that is wired to it will come on as soon as you turn on the main bus, right?
Paul, do you have anything other than your EFIS Displays on your aux battery?
I am really wanting to set up an aux system if nothing else to avoid the reboot of the EFIS's
Hans
Last edited by nucleus : 01-01-2010 at 11:07 AM.
Reason: Another Question
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01-01-2010, 06:38 PM
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VAF Moderator / Line Boy
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Join Date: Jan 2005
Location: Dayton, NV
Posts: 12,256
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A few quick answers Hans -
When I say battery bus, I mean the "always hot" side of the battery (through a fuse). Essentially, the batteries are paralleled, but isolated in one direction. It is not the same as the main bus - different side of the main battery contactor.
I power the Display Heads and AHRS from the Aux Battery feed, and keep the Aux battery on from before start to after shutdown - no reason to turn it off, and i you have a main power problem in flight, you don't have to take a step to turn the Aux on. Simple is your friend!
I have no experience with the Intelligent Power Stabilizer, so can't help you there.
Paul
__________________
Paul F. Dye
Editor at Large - KITPLANES Magazine
RV-8 - N188PD - "Valkyrie"
RV-6 (By Marriage) - N164MS - "Mikey"
RV-3B - N13PL - "Tsamsiyu"
A&P, EAA Tech Counselor/Flight Advisor
Dayton Valley Airpark (A34)
http://Ironflight.com
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01-01-2010, 08:42 PM
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Join Date: Jan 2005
Location: Columbia, SC
Posts: 804
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Quote:
Originally Posted by nucleus
Here is the wiring chart for the GRT Back-up battery, which I find a little obtuse. Do you use just one for all your EFIS's (EFII?), or one each? Should the aux battery pull power off the main or avionics bus? When you say battery bus Paul, is that the same as the main bus? NASA nomenclature? Do you then just run with the aux battery on, or do yo shut it off after startup?
I have questions about using the Intelligent Power Stabilizer too. The wiring diagram for it shows it feeding off the main bus. So this means that each unit that is wired to it will come on as soon as you turn on the main bus, right?
Paul, do you have anything other than your EFIS Displays on your aux battery?
I am really wanting to set up an aux system if nothing else to avoid the reboot of the EFIS's
Hans
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I used their circuitry but with a 7.5 AH battery to power two displays plus AHRS. You want to "power" it (the circuit) with over 14 volts from a logical point in your system so it will charge the battery.
I then took the output and sent it to a small fuse block via a switch. A tap each from there to Display 1, Display 2 and AHRS. Each with appropriate fuse (around 1 or 2 amps ... I forget at the moment).
Operating mode:
1. Get in plane and turn on the "backup battery" (or whatever you want to call it) switch. This starts power up of EFIS (es).
2. Master, fuel pump etc, START. The main batteries can sag all they want but the EFIS(es) keep right on running as this circuit is isolated.
3. Leave switch ON during flight (as Paul does). Battery gets recharged and if everything else failed in the dark of night in the clouds in the middle of a storm over the mountains, blah, blah ... you still at least have the EFIS (with AHRS) telling you which way is up.
Again, this is basically the same as what Paul does with his "homebuilt" version  . I even had built basically the same earlier. It just has the added benefit of having been done by GRT and having the sense wire with settings to tell something about the health of the battery.
Feel free to contact me offline if there are other questions.
James
p.s. AGAIN, at around 8 volts or so you WILL lose the GRT EFIS. Just keep that in mind.
__________________
James E. Clark
Columbia, SC
RV6 Flying, RV6A Cowling
APRS
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01-02-2010, 09:43 AM
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Join Date: Oct 2007
Location: Emmaus PA
Posts: 55
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IPS product solves this problem
Christer got it right,
Our IPS series of products was designed to solve this exact problem. The IPS-4a unit provides protection for up to 4 amps of load and is perfect for systems such as the GRT EFIS. The IPS-4a weighs in at only 8 oz and unlike a battery requires no additional maintenance.
Our IPS-8a version provides up to 8 amps of load current and weighs 14 oz.
All the details are available at www.tcwtech.com
Thanks,
Bob Newman
TCW Technologies, LLC.
RV-10 40176
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01-03-2010, 07:48 AM
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Join Date: Jan 2005
Location: Las Vegas, NV
Posts: 488
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I have a similar setup (two 680s)
and find that I can start up my panel (thru the endurance bus switch) on the left battery and then start the engine on the right battery only. Never had a problem starting on just one 680 (180 hp 8.5 compression ratio). I figure if I ever have a starting problem, I'll just switch off the panel and start the engine on both batteries.
BTW, I always fly with both batteries in the system and charging. I figure if I ever have an alternator problem, I'll have two fully charged batteries to manage my power options (L, R, or both) as the flight requires.
__________________
Terry F.
RV 7A N457RV
250 hours and lovin it! 
Southern Nevada EAA Chapter 1300 - www.eaa1300.org
Paid VAF 03/17
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