Second sv1000 display

I would like to install a second 10 inch Skyview on the passenger side as I think there is too much information for a single display.
I would like to move the moving map to the right and leave the PFD and engine mon on the left.

Dynon says the standard Rotax alternator does not alllow the additional power drain as they heard from VAN's.

Has anybody installed a second unit. I remember having seen pictures on the forum, but cannot find them.

Hi Jack

Here are a couple of links:

http://www.vansairforce.com/community/showthread.php?t=80077

http://www.vansairforce.com/community/showthread.php?t=76926

To date we have 30 flight hours of trouble free dual SV1000 operation in G-TWLV.

In normal cruise flight (both screens on, SL30, nav/strobes on, ANR headsets powered, PM1200 intercom on) the alternator keeps to around 9 amps. With the landing light and fuel pump on it may go to 11 amps.

Van's (and Scott on these pages) are naturally hesitant when it comes to fitting the two displays and I totally appreciate their concerns and position (especially in overloading the system if using the power socket).

All I can say is that in use we have seen no issues to date.

I carefully produced an Apollo 13 load analysis for our aircraft and I would suggest you do the same to give you a worst case scenario for your aircraft (everything flashing, moving, transponding and transmitting etc).

aerofurb said:

I carefully produced an Apollo 13 load analysis for our aircraft and I would suggest you do the same to give you a worst case scenario for your aircraft

Click to expand...

Excelent advice to anyone considering doing any electrical system mods on an RV 12

aerofurb said:

(everything flashing, moving, transponding and transmitting etc).

Click to expand...

I suggest you also add... the current load to recharge a somewhat discharged battery. How would this happen? Low engine RPM with a lot of electrical equipement turned on equals discharge of the Battery. Some possible causes.... airplane sitting quite a while since flown last, extensive idling on the ground (jambed up in traffic for departure at OSH), lots of slow flight, etc.

2nd display

Thanks Jerry

This is what I was looking for.
I also did the power analysis and it is a matter of how long you accept the battery to recharge from startmotor drain.
As you said the Rotax starts very quickly so i cannot see a problem.
I intend to give it a separate breaker and switch on when I need it like you describe.

Did you just connect the 12 volt and network cable between the screens?
Dynon tells me to buy a complete 37p harness but i guess i only need the supply leads and the 3ft network cable ?
Does the second screen need any licensed software or can I buy the cheaper bare unit without any special software ?
I just want the moving map on the second screen.

Thanks for your help

According to one of Van's employees that I talked with at OSH, ASTM standards require that the alternator be de-rated by 20 percent. That means that Van's must design the electrical system to use not more then about 14.4 amps. If registered as E-AB, the builder can do whatever he wants to. If registered as E-LSA, the builder can do whatever he wants AFTER the flight test period.
Is it wise to exceed 14 amps? It depends. The enemy of electrical devices is heat. As long as the alternator and regulator are kept cool, then it is OK to use up to the maximum power that the alternator can deliver. Alternators are self current limiting. It is impossible for them to put out more than rated power unless red-line RPM is increased. Technically, the Rotax alternator is a dynamo. But it is still self limiting. So the electrical system can never draw more than 18 amps from the alternator. Heavy loads that exceed the capacity of the alternator will draw power from the battery.
How do you know if the alternator or regulator are overheating? Without temperature probes, you don't know. Not exceeding 80 percent of alternator capacity will reduce failures.
The voltage regulator is the weak link in the system and is prone to failure if not properly cooled.
Joe Gores

Another valid point from Scott re the initial battery charging (two to charge - the main PC680 and the SV back-up battery).

On start up our ammeter (measuring alternator load) sits around 8 amps. We start with just the P1 screen on and then after start, the P2 screen comes on with the avionics master switch.

One thing with the Rotax is the time taken to get up to 50 deg oil temp for the power checks. By the time you get to take off, the main battery should be pretty much up to full charge.

On the Tecnam P2002-JF Sierra at work we had the regulator fail. This didn't have dedicated cooling to the regulator whereas the RV uses the lighting kit cooling shroud. The Tecnam used a small motorcycle battery and with a GNS430 and non-LED landing, strobe and nav lights, it was easy to flatten the battery whilst in flight.

On our dual SV installation, both screens are set up to give equal info so P1 can be left or right seat. We have the ethernet cable so you update one screen and other follows (upgrading firmware like to v4 required both screens to be done independently).

Only one payment was needed for the licensed nav software on both screens. We are using PocketFMS - much cheaper than Jepp and covers the UK nav info really well. No doubt it will work well in NL too.

ELECTICAL LOADS Base load Addition Peak % time avg interm

Skyview terminal 3.5
Back-up battery charge 1.5 25 0.4
Skyview terminal 2 (no back-up batt) 3.5
Transponder 0.4
2 x SV32 Dynon servo's 2.6
Com radio receive/intercom mode 0.3 Transmit 1.5 6 0.1
Fuel pump Switched 2 10 0.2
Navigation lights 0.4 Strobe 1.8 20 0.4
Landing/Taxi light landing 2 8 0.2
Trim motor occasional 1 1 0.0
Cooling fans 0.6
Master relay 0.1
Instr lights/Leds/hold relays 0.35
AV5000 0.1
Starter motor During start 60 2 1.2

11.9 plus average 2.4

Genarator max current 18 A
De-rating to 80% as per ASTM 14.4 A
Average consumption per above 14.3 A (complies)

Spare current to 100% to recover battery from start 3.7 A
(Battery 13,8 V / 20 Ah)

i.e starting power drain of 1.2 Ah is re-charged in 20 minutes after which load returns to 80%

Power analysis

The import of my calculation sheet messed up on the last post. Sorry.

Anyway in cruise my average load with full time autopilot on and fuel pump off (I prefer to use it as a back-up during start only like in most planes) the load is 11.9 Amps. Averaging occasional loads with their useage % results in 2.4 Amps

I.e this total of 14.3 Amps is just below the ASTM 80% of 18 Amps = 14.4 Amps

I now require the spare regulator capacity to 100% being 3.7 Amps to recharge the battery drain in about 20 minutes which is acceptable.

Note this is a real worst case with both SV1000's on all the time, but of course the 2A of the fuel pump makes adifference.
No back up battery in the second SV1000.

I realise on low RPM is may drain a little but I intend to use the second SV only during long navigation flights where you need it most.

To me it seems like a reasonable solution like Aerofurb has already proven.

By the way I also use FMS to satisfaction and flew thoughout Europe with it.

One thing to know about SkyView is that it will not charge the SkyView backup battery unless your electrical system is above 12.25V, so if you ever really do load up the alternator to the point that it can't support the load, SkyView will shed the load of charging a backup battery.

Power load

Hi

My calculation:

5 A Skyvew and Backup batterie
1.3 A each ? Autopilotservo
2 A max / 0.3 A min Radio apollo 30
0.4 A xx1 transponder
5 A Strobe/ pos. ligth
2 A Landingligth
Up to 5 A power connector
0.2 A My garecht ads-b flarm

This is a possible max. Load 17.2 Amps, with a minimum of 6 A, and a averidge of 11 A.

If you install a second 5 A drain, it would too much.

Daniel, Switzerland

Hufise

Your calculation is too simple and pessimistic i think.

I calculed including use percentages f.i the radio takes 0,3 in receive and transmits 6% of the time (1.5 A) resulting in 0.1 A average.
My calc then uses 0.3 plus 0.1 for the radio.
The average of the Aeroled stobes is much less and the landng light are only on a few minutes per flight.
I do not drain 5 Amps from the connector
I also plan not to install a back battery on the back-up screen

I want to prevent battery drain in full operation and load no more than 80%.
I do not mind if the battery drains a bit only a few minutes during landing as long as the average is ok.
Do not forget i do not use the 2nd sv1000 all the time and can switch it off as well.
Moreover there are RV 12's with two screens with positive results.
I agree you have to be careful but I think this is not risky

Intermittent loads do not have to be considered when calculating the total load on the alternator. The battery can supply extra power for a short time when the alternator is maxed out. Fuse sizes should NOT be used for calculating the current draw of devices. Fuses are sized to prevent nuisance blowing; then the next larger nominal size is chosen. Even if realistic and accurate calculations are made, the actual total load on the alternator could be different. An ammeter can measure the actual load. Unfortunately for those using the AV-50001, the ammeter shunt measures current into or out of the battery, which is pretty close to zero most of the time. If the current shunt was instead located in series with the alternator, then the pilot would know how much current the alternator was producing. That is more useful information in my opinion. If electrical system voltage is 13 or higher, then the pilot knows that the battery is not being discharged. System voltage of 13.5 or higher indicates that the battery is being charged or maintained.
Joe Gores

Check this thread and particularly the list and links to CTLS and how they seem to be running more on the standard alternator in their certified design. Now, maybe they messed up their arithmetic, maybe not. http://www.vansairforce.com/community/showthread.php?t=80077

Hi jack

Yes you rigth, but i forget the fuelpump drain of 2 Amps

Daniel, Switzerland

Mich48041 said:

Unfortunately for those using the AV-50001, the ammeter shunt measures current into or out of the battery, which is pretty close to zero most of the time. If the current shunt was instead located in series with the alternator, then the pilot would know how much current the alternator was producing. That is more useful information in my opinion. If electrical system voltage is 13 or higher, then the pilot knows that the battery is not being discharged. System voltage of 13.5 or higher indicates that the battery is being charged or maintained.

Click to expand...

People have debated this subject for decades based on their personal preference. There is a very specific reason the RV-12 amp meter is configured the way it is (which btw is the same as in most certificated aircraft designed over the years), and maybe without realizing it, Joe explained it perfectly.

If an electrical system has been properly designed, all that is required to determine if an alternator is functioning properly is a volt meter (which the RV-12 has). If the voltage is above about 13 V., the alternator is working properly.
If the pilot receives a low voltage warning they should realizes that they have had an alternator failure. With the amp meter connected to the battery feed line (load meter), the pilot can now use it to analyze the battery load. I.E., the RV-12 uses a 17 amp hour battery. That means a nominally performing / fully charged battery can supply 17 amps for one hour (or 8.5 amps for two hours). With the amp meter connected as a "load meter", the pilot can now shed loads until they get to an amperage load value that will give them sufficient battery power to finish the flight.
If the amp meter were connected to the alternator output, all it can ever tell you (for the most part) is if the alternator is working or not (and we already have the volt meter to tell us that). Once the alternator has failed, the amp meter is useless and the pilot will have to use the battery voltage to guess how much operational time they have left.

I should have known better than to criticize Van's design.
I agree with Scott that it is a matter of personal preference where the shunt is located. That is why I put "in my opinion" in my above post. Each shunt location has its advantages and disadvantages as Scott pointed out. I prefer to know the load on the charging system to make sure that it will not be overloaded. In the event the charging system fails, the pilot should shut off all unnecessary loads, especially lights. You never know exactly how long the aircraft battery will last. It all depends on how old it is and its state of charge. It is nice that the EFIS has a backup battery. The Rotax ignition system is independent and will keep working even if the master switch is turned off.

the pilot will have to use the battery voltage to guess how much operational time they have left.

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That statement is true no matter the shunt location.
If the government told me that I have too many instruments and have to get rid of one, I would pick the ammeter. They do make silly rules sometimes.
Joe Gores

Mich48041 said:

I should have known better than to criticize Van's design.

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I wasn't meaning to criticize your opinion Joe, just clarify for the thousands who lurk here but never post.
I just meant to point out the reasons the choice was made on the RV-12, to configure the amp meter as it is.
I do disagree with your need to monitor the alternator output though... If an electrical system is properly designed, a pilot should not have to monitor the alternator output to make sure it doesn't get over loaded. It wont be possible.

Hey Scott, no offense taken. That smiley face means that I was joking. We do not always agree but our intent is the same: to help other builders.
Joe Gores

I don't think that the intent is to ALWAYS monitor the alt output in amps. A temporary switch to that method would give us real world data -rather than arithmetic based on spec sheets -to let us second-guess Vans decision to not offer two screens and the conflicting CTLS decision. It could confirm if there is a real problem or not and how close to "the line" we would be operating. and id very close, what simple load-shedding things might be done. Would be nice to be able to easily switch back and forth between the methods.

Hufise

I did not forget the fuel pump because I only switch it on during take off and landing. So in the order of 10 minutes per flight.
This saves power but more important i know that the engine fuel pumps works, which I cannot really tell when both pumps are running.
Most Rotax driven planes use this system such as all Diamond planes.

Hotscam said:

I did not forget the fuel pump because I only switch it on during take off and landing. So in the order of 10 minutes per flight.
This saves power but more important i know that the engine fuel pumps works, which I cannot really tell when both pumps are running.
Most Rotax driven planes use this system such as all Diamond planes.

Click to expand...

Just keep in mind.... RV-12 owners that use mogas and choose to operate the back-up electric pump intermittently via a switch, are inducing a higher chance of vapor lock related problems.