Mailing List flyrotary@lancaironline.net Message #63955
From: Todd Bartrim bartrim@gmail.com <flyrotary@lancaironline.net>
Subject: Re: [FlyRotary] Re: back-up power for EC2
Date: Tue, 27 Mar 2018 23:27:13 -0700
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Yeah, I think that's why Tracy had 2 pins for power. The DB37 pin connector is mounted directly to the circuit board, so while not particularly difficult to add a new power connection plug with feeds onto the board, at this point I don't want to reinvent a wheel that has already been flight proven.
  I'll just add a couple of diodes at or just before the connector to have separate feeds. This will protect against any loss of power due to wiring.
   Actually the whole reason this has come up is....
Long ago I had a panel of fuses as per Electric Bob's advice. During my initial flight testing I had a couple of nuisance trips on things like the flaps. I don't recall any on anything serious. But in the years since, I was seduced by the idea of circuit breakers and convinced myself that this was a better idea. So at great effort and some expense I changed out all 37 fuses for CB's (yes that's right, I said 37). Click this link to see pic of panel to see why it was difficult to do.
I know that it was probably a waste of time & money as the fuses were equal if not superior.
   Anyways in the time since, as I've been working under the panel, wiring, testing, etc, I managed to accidentally pop a few CB's, but what was disconcerting was that one of CB's was toast and not able to reset at all. Now admittedly these are not aircraft grade CB's (like most of my plane), but they are affordable and they fit in place of the previous panel mount fuses and I've had good service from them in other applications (I replaced all the panel mount fuses in my camper with them long ago).
  So I analyzed my electrical system and everything else that is critical to flight already has redundancy with their own power feed such as primary & secondary injectors, leading & trailing coils, 2 fuel injection pumps, etc. The only weak link to this is the EC2 power supply and in the extremely unlikely event of a short in the wire supplying power and either the inability to reset the breaker or continued tripping due to a continued short, then a redundant power supply would avoid the "dark & stormy night" scenario.

Todd     (If I didn't like building stuff so much, I don't know what I'd do with all that time & money)


Todd Bartrim

On Tue, Mar 27, 2018 at 9:41 PM, Andrew Martin andrew@martinag.com.au <flyrotary@lancaironline.net> wrote:
Be careful if you decide to separate the Vin inside the ec2, I thought each pin in those plugs is only rated to 1a, so both need to supply power at all times.
Andrew

On Wed, 28 Mar 2018 at 11:37 am, Todd Bartrim bartrim@gmail.com <flyrotary@lancaironline.net> wrote:
Ah, yes. I understand you now. I've used them myself in the past. I used on to isolate my endurance buss from the main buss.
Just looked at your link and yeah, thats the same idea. I never used the heatsink though. Also used one to wire up my landing lights with an alternate feed for a wigwag flasher.
  I think at work I probably have in my spare parts bin several large diodes as well.
Yes, that should be fairly easy to accomplish.

Thanks. Anybody else have any comments? Tomorrow...

Todd   (everybody back east is in bed already, while they're just getting up down under)

Todd Bartrim

On Tue, Mar 27, 2018 at 8:12 PM, Andrew Martin andrew@martinag.com.au <flyrotary@lancaironline.net> wrote:
No. Add one of those 4 post diodes externally. If I can find mine I’ll post part number. But pretty sure they are about 25a capacity, you only use 3 of the pins, 2 in, 1 out. I think they are designed as rectifier, but are really good for putting 2 power supplies into 1 load.
Andrew

On Wed, 28 Mar 2018 at 11:04 am, Todd Bartrim bartrim@gmail.com <flyrotary@lancaironline.net> wrote:
Hi Andrew;
  Are you suggesting that the EC2 has an internal diode bridge for this isolation function? I just checked and have 0.3 ohm between pins, indicating they are common internally. However I should mention my EC2 is an original model (serial #315) and I believe Tracy may have changed a few things in later versions. It has been updated but this is only for firmware and not hardware.
  

Todd Bartrim

On Tue, Mar 27, 2018 at 7:53 PM, Andrew Martin andrew@martinag.com.au <flyrotary@lancaironline.net> wrote:
Todd, a diode bridge in between allows 2 separate power feeds and keeps them isolated.
Andrew

On Wed, 28 Mar 2018 at 10:50 am, Andrew Martin <andrew@martinag.com.au> wrote:

On Wed, 28 Mar 2018 at 10:46 am, Todd Bartrim bartrim@gmail.com <flyrotary@lancaironline.net> wrote:
Has anyone provided redundant power sources for their EC2?
  Currently I have power supplied via a circuit breaker, but I'm considering adding another power supply wire fed with a fuse.
However they would both still feed through pins 33 & 34 which are internally connected. So even if I was to separate these pins for there own feed (they are currently fed from the same wire), a short on either one would likely cause both the fuse and CB to blow. 
   I'm just trying to take care of a last few things on my list before taking this plane up to the airport and something I'd added to the list many years ago was redundant power for the EC2 since a failure of that could really ruin my day.
    Since the most likely point of failure (even though it's quite unlikely) would be the DB37 pin connector on the EC2, I'm not sure that it is worth the effort to open up the connector shell to add another power wire.
  I've changed my mind on this several times over the last while and now I'm running low on time so I'd throw it out for the collective wisdom of the group.

Todd Bartrim    (can't think of anything witty to sign off with) (I still miss Rusty's witt, for those that remember him)

C-FSTB
RV9 Turbo13B
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Regards Andrew Martin Martin Ag

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Regards Andrew Martin Martin Ag

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Regards Andrew Martin Martin Ag

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