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  #1  
Old 06-04-2018, 12:24 PM
Larry DeCamp's Avatar
Larry DeCamp Larry DeCamp is offline
 
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Location: Clinton, Indiana
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Default SDS CPI breaker/fuse question ?

Install docs and recent threads refer to breakers and fuses. I could consult Ross, but for the benefit of all who might care, are fuses as specified by SDS the bottom line for the coils and ECUís ?
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RV-3B flying w/ carb & Pmags
RV-4 fastback w/ Superior EXP 0360 /AFP & CPI
Clinton, IN
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  #2  
Old 06-04-2018, 12:52 PM
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rv6ejguy rv6ejguy is offline
 
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Default

You may use breakers or fuses as you prefer. They are really there to protect the wiring in most cases.

The ECUs, individual injectors and coils draw less than about 2 amps nominally, though short term surge current is higher on the coils and injectors for a millisecond or two, hence our cautions about setting breaker thresholds when using a VPX.

The fuel pumps draw the most current at around 4.5-5 depending on fuel pressure and surge current will exceed 10 amps on these.
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Ross Farnham, Calgary, Alberta
Turbo Subaru EJ22, SDS EFI, Marcotte M-300, IVO, RV6A C-GVZX flying from CYBW since 2003- 424.4 hrs. on the Hobbs,
RV10 95% built- Sold 2016
http://www.sdsefi.com/aircraft.html
http://sdsefi.com/cpi.htm


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  #3  
Old 06-07-2018, 11:05 PM
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Location: Spring Hill, KS
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Default Combining pump, coil, and ECU on one fuse

Ross, the SDS EFI wiring diagram for a 4 cyl Lycoming shows a 2A fuse for an ECU channel, 10A fuse for a coilpack, and 15A fuse for a pump. If I were to combine these together (to reduce the number of switches in the panel), would a 20A fuse be big enough or would the combined inrush of the coil, pump, and ECU coming on together possibly blow a 20A fuse even though the steady state current for those three things combined is less than 6A?
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  #4  
Old 06-08-2018, 05:38 AM
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rv6ejguy rv6ejguy is offline
 
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25 amp would probably be fine with one pump on but it's not standard practice to place several critical components on the same breaker or fuse especially where redundancy is concerned.

I'm a big fan of ATO type fuses. A fuse block to hold these behind the panel can be added if you were installing EFI in an existing airframe where you had no more breaker space or even in a new airframe.

I've used these for 30 years in race cars and aircraft, never had any issues with fuses coming loose or losing contact. Have had 3 of these blocks in my RV for 15 years now.

In the case of the CPI, where we're just driving the module and coils, you could use one fuse for a module and its coil pack since if either one goes down, you lose spark on that coil pack anyway. You'd want the 2nd ignition system to be on a 2nd fuse or breaker of course.
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Ross Farnham, Calgary, Alberta
Turbo Subaru EJ22, SDS EFI, Marcotte M-300, IVO, RV6A C-GVZX flying from CYBW since 2003- 424.4 hrs. on the Hobbs,
RV10 95% built- Sold 2016
http://www.sdsefi.com/aircraft.html
http://sdsefi.com/cpi.htm



Last edited by rv6ejguy : 06-08-2018 at 05:41 AM.
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  #5  
Old 06-08-2018, 08:09 AM
Larry DeCamp's Avatar
Larry DeCamp Larry DeCamp is offline
 
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Default CPI question for Ross ?

Thanks for the "one fuse for CPU & coil " comment. Less is more. That said, I wondered if the CPU tolerates intermittent cycling ? I was planning to power the cpu from the buss and have a switch for the coil only to " mag Check".
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RV-3B flying w/ carb & Pmags
RV-4 fastback w/ Superior EXP 0360 /AFP & CPI
Clinton, IN
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  #6  
Old 06-08-2018, 08:44 AM
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rv6ejguy rv6ejguy is offline
 
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Quote:
Originally Posted by Larry DeCamp View Post
Thanks for the "one fuse for CPU & coil " comment. Less is more. That said, I wondered if the CPU tolerates intermittent cycling ? I was planning to power the cpu from the buss and have a switch for the coil only to " mag Check".
The CPI has a runup feature to stop sparks at the CPU output level while keeping the CPU powered and running.

If you want to cut power to check coils, I'd cut coil power rather than CPI module power to do this.
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Ross Farnham, Calgary, Alberta
Turbo Subaru EJ22, SDS EFI, Marcotte M-300, IVO, RV6A C-GVZX flying from CYBW since 2003- 424.4 hrs. on the Hobbs,
RV10 95% built- Sold 2016
http://www.sdsefi.com/aircraft.html
http://sdsefi.com/cpi.htm


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  #7  
Old 06-08-2018, 01:51 PM
Ron77 Ron77 is offline
 
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Location: Kemah, Texas
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Default Question Larry

Hey Larry, are you ready to sell me your Pmags yet?

Ron B.
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  #8  
Old 06-08-2018, 05:43 PM
Larry DeCamp's Avatar
Larry DeCamp Larry DeCamp is offline
 
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Default Ron

Not ready because time spent putting CPI on the -3 would simply be time not finishing the -4. Donít wait for me to get your Pmags. My 0320 with Catto and EartHX are just a joy to work with.
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RV-3B flying w/ carb & Pmags
RV-4 fastback w/ Superior EXP 0360 /AFP & CPI
Clinton, IN
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  #9  
Old 06-08-2018, 07:19 PM
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czechsix czechsix is offline
 
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Quote:
Originally Posted by rv6ejguy View Post
If you want to cut power to check coils, I'd cut coil power rather than CPI module power to do this.
Does this advice apply to the EFI ECUs as well? I was planning a switching scheme where I could shut off one channel at a time while also switching the injector relays in order to do a full check of all redundant components in the system during run-up. Based on a previous email, it sounded like the EFI ECUs take a second or two to power up and start commanding spark & injectors, so I would expect the engine to sputter for a moment during this procedure (only done on the ground). But as long as the ECU isn't commanding any spark or injectors until it is fully booted up and come to its senses, there shouldn't be any backfire, kickback, or other bad things that happen...it would just miss a few revolutions and then pick up running normally again?
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RV-8A N2D #80583 - built/flew/sold
RV-14A #140017 - wings complete, empacone in progress...
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  #10  
Old 06-09-2018, 10:47 AM
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rv6ejguy rv6ejguy is offline
 
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You don't really want to shut down ECUs to check spark. Currently there is no runup check on the EM-5 so we recommend having coil power switches to check each ignition with dual ECUs.

The ECUs boot up in about .15 seconds and don't command any spark events until 1 crank rev establishes a time interval between magnets. Software changes about 5 years ago allow a seamless transition even turning the ECU off and then on at full rpm.

On the EM-6, we're likely to add a runup feature like the CPI has.
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Ross Farnham, Calgary, Alberta
Turbo Subaru EJ22, SDS EFI, Marcotte M-300, IVO, RV6A C-GVZX flying from CYBW since 2003- 424.4 hrs. on the Hobbs,
RV10 95% built- Sold 2016
http://www.sdsefi.com/aircraft.html
http://sdsefi.com/cpi.htm


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