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  #1  
Old 07-09-2020, 10:56 PM
N546RV's Avatar
N546RV N546RV is offline
 
Join Date: Aug 2010
Location: Brookshire, TX
Posts: 1,202
Default Couple SDS CPI2 install questions

Planning, planning, planning...such is my life these days. This must be that last 90% everyone talks about. This has surfaced a couple questions about installing/packaging the CPI2 components.

#1: How accessible should the ECU and backup battery units be? Both these units have fuses that might require service at some point. I have no expectation of making them accessible in-flight, but I'm also not sure that burying them behind the panel is smart either.

My first inclination was to package the ECU alongside my fuse blocks, which I intend to place on a hinged mount behind the panel for on-ground accessibility, but getting the ECU on there alongside the fuse blocks and associated stuff is pretty tight. Moving the ECU to my upper avionics shelf - which will only be accessible by removing the center of the panel - would make things a good bit roomier.

I figure in a general sense if these fuses are blowing on any regular basis, I've got obvious issues, so I suppose this mostly comes down to possibly dealing with teething problems early on. I still feel like overall, having these units somewhat buried wouldn't be a bad thing.

#2: I'm interested in the "switchology" for the CPI2. I'll be full electronic, and thus running a dual ECU unit. I intend to use toggle switches, not a key switch, for ignition control. My current schematic iteration has two DPST switches, one for each ECU. Each switch controls power to the ECU and coil (purple and red wires) for that ECU.

What I'm wondering is whether I should also provide a way to kill the coils with a dedicated switch or switches, either for the purpose of killing the engine quickly, or for killing the coil packs individual (as with a traditional mag check). I know all the preflight stuff can be done from the controller - is there any benefit to using the controller in lieu of external switches for the runup procedure?

One thing I thought about was to replace those DPST switches with ON-OFF-(ON) DPDT switches for this purpose. The center position would of course have everything powered off, up would be the normal "on" position in-flight, and down would be the momentary position, and could activate the external kill function for the connected ECU. This would enable both traditional "mag checks" as well as the ability for a quick engine kill.

The other alternative would be to simply have a third switch that killed both ECUs, and was used only for an emergency shutdown, and all runup operations could just run through the controller.

This is definitely the more fun question, and I'm very interested in people's thoughts here. Thanks!
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  #2  
Old 07-10-2020, 01:54 AM
leok leok is offline
 
Join Date: Apr 2013
Location: Clarkston, MI
Posts: 435
Default My Installation

I have been running the dual CPI-2 for almost 100 hours. I have had to access the main control box exactly one time. That was to add an SDI recommended capacitor to quiet false low current indications in my particular system. No fuses have ever blown. I have power for one side fed through my VPX-pro system and one side fed through a direct battery buss (bypassing the master). I would suggest that having access for occasional maintenance is critical, but you will not need regular access to the fuses.

My battery is low on the forward firewall. I would have put it inside the cockpit if I could have made a spot that was easy to service, but completely out of the way. I mounted it low and outboard to keep it out of the high heat after shutdown, but high enough to be away from the exhaust. The back of the engine is a pretty busy environment with access needed for regular oil filter access. I am sure in the cabin would be a kinder environment for the battery life, but nowhere to put it.

Switchology is another matter. You will need two on off switches to power the system up. You can do the run-up mag check on the head, but it is not very straightforward with a lot of button pushing. Having dedicated switches to tell the system to suspend ignition 1 and 2 for an ignition check is faster and more straight forward in my opinion. With its own internal back up power you will also need a switch to tell the system to shut down. Simply turning off the power will only switch it to back up power.

I found it simpler to use a traditional key switch to accomplish all of those tasks. Starting the engine is simply to turn on the two CPI systems power and key the starter. Run up ignition check is key position 1 and 2 ‘mag’ check. Shutting down is mixture, system power switches off, key off. All accomplished with two power switches and 1 key switch.

Once the false ‘low volts’ issue was solved with the addition of the capacitor, the system has been flawless. I have an IO540 thunderbolt. I just flew a 1310 nm trip from SLC to PTK at 11,500 alt, WOT fuel flow of 10.5 to 11 gph (lean of peak), 2450 rpm with an average of 160-165 kts true airspeed. I was in loose formation with another RV10 (1 mile lateral separation). When I switched on the LOP advance I picked up 2-3 kts and slowly pulled away from the other 10. I am a happy customer!
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Last edited by leok : 07-10-2020 at 01:56 AM.
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  #3  
Old 07-10-2020, 06:14 AM
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DanH DanH is offline
 
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Location: 08A
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Default

Quote:
Originally Posted by N546RV View Post
#1: How accessible should the ECU and backup battery units be? Both these units have fuses that might require service at some point.
I'm all for service access, but anything which can be reached in ten minutes with simple tools is plenty good here.

Quote:
I'm interested in the "switchology" for the CPI2.
It's in the manual.

For each ECU and coil, one DPST for the purple and red power supply wires, and one SPST switch for runup check, gray wire for left IGN, yellow for right IGN. When closed, the SPST switch grounds the circuit and shuts down the respective ignition.

The runup switch can be a toggle wired to be normally open, or a normally open push button, or a rotary key switch. I'd pick the toggle, mounted upside down so up is open. I'd rank the rotary switch last for reliability, but operation is innate for a pilot transitioning from most traditional GA birds. That is a big plus. Always good if your switchology conforms with convention.

Quote:
One thing I thought about was to replace those DPST switches with ON-OFF-(ON) DPDT switches for this purpose. The center position would of course have everything powered off, up would be the normal "on" position in-flight, and down would be the momentary position, and could activate the external kill function for the connected ECU. This would enable both traditional "mag checks" as well as the ability for a quick engine kill.
If the engine was running, the center OFF would make the system switch to the backup battery, not quick kill.

That's not necessarily a bad thing. Up would be normal run, middle would check operation of the backup system, and the spring-loaded down would kill ignition for runup checks. It would be a one switch runup pad function check for each ignition.

Note that to shut down the engine using the ignition switch rather than the mixture knob, you would need to hold both switches in the down position at the same time until engine rotation ceased. Only then would releasing the switches put the systems in a fully OFF mode.

Quote:
The other alternative would be to simply have a third switch that killed both ECUs, and was used only for an emergency shutdown, and all runup operations could just run through the controller.
Not just no. Four letter no
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Last edited by DanH : 07-10-2020 at 06:17 AM.
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  #4  
Old 07-10-2020, 06:20 AM
F1 Rocket F1 Rocket is offline
 
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Default

I?m in the process of gathering up all the components to convert my Rocket to a dual CPI-2 set up. I have two double pole switches that will control CPU/coil power to ignition A and B. I also have two momentary push buttons that will be wired to shut down either ignition. I thought I had everything handled with the this setup but after reading the above posts I?m asking myself: ?What prevents the engine from running off the backup battery once the two main power switches are turn off and the engine is shut down?? In other words, will the back up battery fire the ignition if the prop is turned on the ground? Do I need a separate switch to shut off the back up power?
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  #5  
Old 07-10-2020, 07:06 AM
F1 Rocket F1 Rocket is offline
 
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Default

Ok...RTFM:
? Power down of the CPi2.
Due to the ecu having its own backup battery, power down is unique on the CPi2. When you turn off Mainbus 12 volt
power to the CPi-2 it automatically switches over to its backup battery. If there is no engine rpms, and no keypad keys are pressed, it will begin a power off countdown within 5 seconds, and after counting down from 10 to 0 it will shut off unless Mainbus power is switched back on. So total power off time is approximately 15 seconds.?

So stay clear of the prop within 15 sec of shut down.
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  #6  
Old 07-10-2020, 07:29 AM
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agirard7a agirard7a is online now
 
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Location: Newport, RI
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Default CPI-2

I do my run up check using the controller. It’s very easy and efficient. The system from the control head, momentarily shuts off a coil for a few seconds and then it fires back up automatically. It allows you to check both coils independently.

I have the main system wired to my master buss. When the master is on it powers up an ignition bus ( made by Blue Seas) with 4 circuits ( 2- 3amp fuses, 2 -10 amp fuses).
I also have two dipole switches which can cut off the power individually to each coil. These are switched after the ignition bus.

I use a key start, the two dipole switches, located just above my ignition switch( up for on), obviously have to be turned on to start the engine. When I shut down, I pull the mix, shut off both switches, turn off the key, turn off the master. The dipole switches are needed. I first had the system wired without them just using the master. The problem was there was some apparent left over voltage in my panel wiring. (back up batteries) that kept the control head from completely shutting off. The system works well.
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Last edited by agirard7a : 07-10-2020 at 08:05 AM.
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  #7  
Old 07-10-2020, 12:52 PM
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N546RV N546RV is offline
 
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Location: Brookshire, TX
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Default

Quote:
Originally Posted by DanH View Post
If the engine was running, the center OFF would make the system switch to the backup battery, not quick kill.

That's not necessarily a bad thing. Up would be normal run, middle would check operation of the backup system, and the spring-loaded down would kill ignition for runup checks. It would be a one switch runup pad function check for each ignition.

Note that to shut down the engine using the ignition switch rather than the mixture knob, you would need to hold both switches in the down position at the same time until engine rotation ceased. Only then would releasing the switches put the systems in a fully OFF mode.
Yup, this is pretty much exactly the procedure I had in mind; I kind of feel like the switch setup has a certain elegance to it.
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  #8  
Old 07-10-2020, 03:47 PM
sjarrell sjarrell is offline
 
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Location: Hendersonville, NC
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Default

Quote:
Originally Posted by F1 Rocket View Post
I?m in the process of gathering up all the components to convert my Rocket to a dual CPI-2 set up. I have two double pole switches that will control CPU/coil power to ignition A and B. I also have two momentary push buttons that will be wired to shut down either ignition. I thought I had everything handled with the this setup but after reading the above posts I?m asking myself: ?What prevents the engine from running off the backup battery once the two main power switches are turn off and the engine is shut down?? In other words, will the back up battery fire the ignition if the prop is turned on the ground? Do I need a separate switch to shut off the back up power?
From the installaton manual:

If you don?t have a typical aircraft key/mag type switch, you can wire up yellow and gray to one or two normally open momentary push switches or toggle switches to kill ignition which will then shut down the engine. Remember turning off Mainbus power to the CPi2 just forces it over to backup battery power so your Mainbus or ecu power switch will not shut off the engine.

So, use your key switch to turn the ignition off. That grounds the ignition just like it would if you had traditional mags. Otherwise the engine is going to keep happily running until the CPi-2 backup battery runs out of power.

SDS also recommends having a separate switch from the master switch to prevent back feed as was mentioned previously, and separate breakers for the coilpack and cpu for each of the CPi-2 units. So, if you have a dual unit you'll need a total of 4 breakers and two double pole switches. Each switch controls power to one cpu and one coilpack via the main CPi-2 control unit.
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  #9  
Old 07-10-2020, 03:51 PM
David Carter David Carter is offline
 
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Location: Alpharetta, GA
Posts: 157
Default You can do this with only two switches

I've been running a dual CPI-2 setup for just over a year. Great unit. Like an earlier poster, I've only needed access once to install a capacitor into each of two wiring connectors.

I'm finalizing a new panel design with SteinAir, and based on feedback from SDS, I will be using a pair of locking toggle switches to provide "off", "run", and "mag check" positions for each ECU.

That portion of the panel design looks like this:



This is a wiring diagram that I got from SDS. I understand that this was created by another SDS customer, and reviewed by SDS.



I'm very tight for panel space, so this makes the most of a limited amount of real estate.
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  #10  
Old 07-10-2020, 04:47 PM
sjarrell sjarrell is offline
 
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Location: Hendersonville, NC
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Default

Quote:
Originally Posted by David Carter View Post
I've been running a dual CPI-2 setup for just over a year. Great unit. Like an earlier poster, I've only needed access once to install a capacitor into each of two wiring connectors.

I'm finalizing a new panel design with SteinAir, and based on feedback from SDS, I will be using a pair of locking toggle switches to provide "off", "run", and "mag check" positions for each ECU.

That portion of the panel design looks like this:



This is a wiring diagram that I got from SDS. I understand that this was created by another SDS customer, and reviewed by SDS.



I'm very tight for panel space, so this makes the most of a limited amount of real estate.
It appears you have both CPUs and Coilpacks wired directly to the main bus through the switch. SDS recommends individual breakers or fuses for each CPU and each Coilpack.

You may want to double check this with Ross or Barry.

From the installation manual:

"The Purple 20 ga on the 14pin main harness plug, needs a 2 to 5 amp fuse or breaker."

"The Red 18 ga wire on the 12pin coil harness plug. Needs a 10 to 15 amp fuse or breaker."
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