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Why does the Surefly need continuous, uninterrupted power?

moespeeds

Well Known Member
Friend
Why does the Surefly need continuous, uninterrupted power even when parked?

I'm running wires for my Surefly single mag install today. I understand the need for uninterrupted power during flight, this is obvious.

But Surefly is calling for constant uninterrupted power even with the engine off. Considering that I'm using an Earthx LIFO battery and the associated issues with draining these things, I'd rather not worry about a continuous draw on it when I leave the plane sitting on the ramp for days or more on a trip somewhere.

The draw is 1 milliamp, I know this is tiny, but what's the purpose?

The difference in install would be a direct connection to the battery, or to the airframe side of the master relay.

Am I reading this diagram correctly that it can't be switched?
 

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According to the installation manual, yes.

They recommend keeping the aircraft on a tender if it sits for more than a month, but things like this tend to live in my head at night so I'd much rather have a switched connection to the thing.
 
pretty sure that addition to the manual came from the lawyers. I am guessing they don't want to be blamed / sued for an electrical issue that interrupted power to their units and take the plane down, like someone turning off the master or pulling a breaker. Remember, these are certified units and can easily see the pilot blaming someone for not knowing that this "mag replacement" required power via the master. These are sold as drop in replacements for mags and should expect pilots to treat them accordingly.

Larry
 
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That was my thinking Larry. Considering the installation is geared towards Certified aircraft, this could be legal BS.

Considering that at least in my understanding, all settings are analog via dip switches, I see no reason for this.
 
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The data suggest that a new PC680 battery has 16 Ah (amp hours) of juice. The Surefly draws 1 milli amp when at rest. Higher level mathematics indicates that after 1000 hours, or 41 days, a single Surefly would consume 1 amp of juice from the PC680. 15 Amps are left to start the engine. It does not seem like a big deal to me.

If a switch is added between the panel and the Surefly, then multiple failure points are added...at least two additional connectors, each connector has a crimp, and the switch, or CB or fuse itself. I count five failure points to add a switch.

I'm not saying don't add the switch. Rather, try to see Surefly's logic. Simplicity is beautiful.
 
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If there is anything in the manual that talks about what to do after losing electricity to the SIM, that might give some clues about how critical a 24x7 connection actually is.
 
If there is anything in the manual that talks about what to do after losing electricity to the SIM, that might give some clues about how critical a 24x7 connection actually is.

Nothing I saw, except that an interruption of power would cause a SIM reset, with a second of engine roughness while running.
 
clock

Correct me if I am wrong, didnt the old cessnas have clocks on board that constantly drew power? how much current was that?

But this would be a deal breaker for me too. I never liked things (except pets and wives) that would die if left unattended
 
I've been flying the SureFly for a couple of years. The keep-alive circuit has never caused any issues on my plane, the $40 PC680 wannabe battery has always started it even after a 3-4 week break from flying.

I consider the keep-alive circuit to be a non-issue and agree it's purpose is to eliminate factors that would interrupt the power supply. The only thing between the SureFly and constant battery power is an inline fuse.
 
If there is anything in the manual that talks about what to do after losing electricity to the SIM, that might give some clues about how critical a 24x7 connection actually is.

It didn't ship with a battery did it? Do they provide instructions on what to do if the battery in your plane goes dead? You get the point. No technical reason that it needs constant power.

Larry
 
Last year I put a new battery in my SIM equipped airplane. Old out, new installed about an hour later. Nothing reset, nothing needed attention, started same as before (the starter did spin with more enthusiasm), ran same as before. What does the 1 ma drain actually do?
 
Same for me using a EarthX battery with a Surefly. The draw is so low the plane would have to sit for months. Ours has never been on a tender.
 
If I’m not mistaken, if the sim is connected to the master solenoid positive terminal, there is no power to it unless the battery (master solenoid) switch is turned on. Therefore no battery drain.
 
That is not how they want it wired. They want it to the positive battery terminal or to the battery side of the master solenoid. The reason is obvious.
 
Well Sailvi since the "reason is obvious" and the guys that previously posted didn't allude to the reason, please enlighten the rest of us.

If it's for certification reasons, I know how I'm going to wire mine. But, if there is indeed an electrical requirement inside the unit that has yet to be revealed....
 
If I’m not mistaken, if the sim is connected to the master solenoid positive terminal, there is no power to it unless the battery (master solenoid) switch is turned on. Therefore no battery drain.

I"m pretty sure most master solenoids have their + terminal "hot", e.g., connected to the battery. The master switch switches the - side to ground. Any other way, you need to run a hot (hopefully fused) wire up to the panel, then back to the solenoid.
 
Well Sailvi since the "reason is obvious" and the guys that previously posted didn't allude to the reason, please enlighten the rest of us.

If it's for certification reasons, I know how I'm going to wire mine. But, if there is indeed an electrical requirement inside the unit that has yet to be revealed....

The unit ceases to function with a loss of power. There are many aircraft malfunctions that could require turning off the aircraft master.
 
Why dont you install a pull Off style breaker in the always hot line to that Surefly. With that you could always pull that breaker if you wanted to disconnect it from the power source for some reason. Actually thats the way my Plasma II is wired. Dont recall ever pulling that breaker for any extended time period. The breaker is NOT located with the other master switched power items but over close to the mag switch and labeled "CDI PWR"
 
One milliamp is .001 amps. Almost nothing. Cars since the mid eighties draw 35 to 60 milliamperes or more just sitting. Some will draw 2 to 4 amps for a couple of hours after shutdown and then slowly go down to the 40 milliamp range.

One milliamp would not concern me

Bob Grigsby
Flying Cub regularly
Just bought a rudder for the Cub before the FAA AD hits
 
Sam and Dan both hit the nail on the head.

Continuous power only removes extra parts that cause failure points. An added switch adds failure points. The extra short section of wire, two extra connections, and the switch all add to possible failure modes.
 
Well Sailvi since the "reason is obvious" and the guys that previously posted didn't allude to the reason, please enlighten the rest of us.

If it's for certification reasons, I know how I'm going to wire mine. But, if there is indeed an electrical requirement inside the unit that has yet to be revealed....

I originally had my Surefly power wired to master solenoid to avoid draw as some have suggested. Then one day (during phase 1 flight testing) I started plane and found cockpit filling with smoke!! Thank goodness I was still on the ground. Turned master switch off immediately to cut electrical to everything and smoke quit. I had a potentiometer in my panel fail that was running a NACA vent controller.

I then realized why I needed Surefly wired direct to battery. In event of electrical fire, I need to turn master off, but would rather have both ignitions still working. Mine is now wired directly to battery as suggested in Surefly's material.
 
SNIP
I then realized why I needed Surefly wired direct to battery. In event of electrical fire, I need to turn master off, but would rather have both ignitions still working. Mine is now wired directly to battery as suggested in Surefly's material.

This is a key design point for power distribution schemes - but for the IFR panel as well as anyone flying with a ship power dependent engine.

On my RVs, the POH immediate action for any electrical issue is to open both Master solenoids. This removes the “fat” wires from the batteries and establishes a fully split system, each side of the panel gets an independent feed via 30 amp relays (no pilot action required). Reserve power is adequate to support full IFR flight (EFIS, NAV/Comm, XPDR, etc.) for 1.5 hours (one battery available) or 3 hours (both batteries available). No additional backup batteries are used.

Carl
 
This is a key design point for power distribution schemes - but for the IFR panel as well as anyone flying with a ship power dependent engine.

On my RVs, the POH immediate action for any electrical issue is to open both Master solenoids. This removes the “fat” wires from the batteries and establishes a fully split system, each side of the panel gets an independent feed via 30 amp relays (no pilot action required). Reserve power is adequate to support full IFR flight (EFIS, NAV/Comm, XPDR, etc.) for 1.5 hours (one battery available) or 3 hours (both batteries available). No additional backup batteries are used.

Carl

If the smoke keeps coming after turning off your “masters” (small wires can produce copious amounts), now what do you do?
You will literally have seconds to decide what’s next before you’re in big trouble as the CP fills with smoke.
Tefzel wire may not produce a flame but they will smoke more than you think if shorted (I’ve seen this up close).
 
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Added the Surefly on my 7 wired as they suggested for continuous power from my EarthX but put the removable blade type fuse fixed below the oil door for easy access and quick removal if the plane will sit for a few weeks.
 
If the smoke keeps coming after turning off your “masters” (small wires can produce copious amounts), now what do you do?
You will literally have seconds to decide what’s next before you’re in big trouble as the CP fills with smoke.
Tefzel wire may not produce a flame but they will smoke more than you think if shorted (I’ve seen this up close).

Yep, this low risk issue is covered in my POH, and the design supports continued flight.

Carl
 
Yep, this low risk issue is covered in my POH, and the design supports continued flight.

Carl

My thoughts, having experienced a cockpit filling with smoke from a single 18ga unprotected (from the battery to CP) shielded wire that shorted and turning off the master didn’t stop the smoke, is that first you would be lucky to survive, and secondly I would never let another aircraft leave my shop with unprotected wires coming directly off the battery and entering the CP.

Bypassing the master contactor totally defeats it’s purpose.
If you think you have time to figure out or isolate the issue, we’ll good luck with that unless you’re wearing a smoke hood.
 
Confused

So i am a little confused by this thread.
The Surefly requires continuous power.

But yet some people are putting in a switch.

So my confusion, does it need continuous power only when operating, or does it need continuous power all the time, say to keep some memory alive?
 
So i am a little confused by this thread.
The Surefly requires continuous power.

But yet some people are putting in a switch.

So my confusion, does it need continuous power only when operating, or does it need continuous power all the time, say to keep some memory alive?

Does not need continuous power except for when operating, they provide a fuse to protect the power wire and recommend putting it on the hot battery side so if you do need to turn off the master in flight it won’t kill your ignition.
 
So i am a little confused by this thread.
The Surefly requires continuous power.

But yet some people are putting in a switch.

So my confusion, does it need continuous power only when operating, or does it need continuous power all the time, say to keep some memory alive?

The config for the SureFly is set with DIP switches, not user-defined software. The switches are set to determine either fixed or variable timing and the base timing. Once the switches are set, the initial timing is similar to a magneto, rotate the device until properly timed.

The constant power is for fail-safe operation, not retaining configuration. Some folks are trying to make this way too complicated. One of the major features of the SureFly is that it is pretty much a plug-n-play replacement for a magneto and doesn't require any solid-state ignition black magic to make it work. Just remove the mag, insert the SureFly retaining the existing harness, hook up one wire for constant power from the battery, time and fly. :)

It's all here:

https://www.surefly.aero/_files/ugd/f0684a_8989a7acb55d46619355cc83ba653ef1.pdf
 
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Perhaps some are seeing the term SIM, and are picturing a sim-chip out of a cell phone...........:confused:

Surefly Integrated Module

Stranger things have happened! :rolleyes:
 
My thoughts, having experienced a cockpit filling with smoke from a single 18ga unprotected (from the battery to CP) shielded wire that shorted and turning off the master didn’t stop the smoke, is that first you would be lucky to survive, and secondly I would never let another aircraft leave my shop with unprotected wires coming directly off the battery and entering the CP.

Bypassing the master contactor totally defeats it’s purpose.
If you think you have time to figure out or isolate the issue, we’ll good luck with that unless you’re wearing a smoke hood.

Why do I feel compelled to defend someone else's product? I dont know, But I do. I think I seek truth and want to enhance this website.

It seems to me that this post assumes that the installation calls for unprotected wiring. That is not true.

If we inspect in Post #1 the Surefly installation diagram from the Surefly installation manual we can see that all wiring of these ignition units are protected with a 10A circuit protection device. This is a very robust and generous circuit protection. It seems to me a very prudent and responsible installation.

The last 2 sentences of that post is bad advice. Bypassing the master is good design in this installation.
 
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So continues power is only required to satisfy the certified installation, and will not adversely affect the ignition as long as the engine is off.

Protecting the wire with the recommended 10a fuse at the battery seemed so obvious to me that I didn't bother mentioning it.

With one standard mag to keep the engine running without power, is it worth it to switch the thing via the master? I also can't stand long wire runs that I can't turn off, and this would be the only wire in my aircraft that won't cut off via the master. It's a 14ga mil-spec wire, about a 9 foot run, secured and grommeted the whole way with a 10a fuse at the battery.

I also have a separate power cutoff on the landing gear box that would break the 2ga battery cable before any of the aircraft systems, while leaving the master relay in the back closed/powered. In the event of an electrical emergency where I had to cut all power to the panel and systems, but not related to the battery, I would simply switch this connection and the surefly would continue to get power off the airframe side of the master while all other systems would be cut.

Considering that any in-flight emergency requiring the master to go off would likely originate at the battery in the back anyway, making the unbroken ignition run moot.

I guess I'll have to mull this one over.
 
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Why do I feel compelled to defend someone else's product? I dont know, But I do. I think I seek truth and want to enhance this website.

It seems to me that this post assumes that the installation calls for unprotected wiring. That is not true.

If we inspect in Post #1 the Surefly installation diagram from the Surefly installation manual we can see that all wiring of these ignition units are protected with a 10A circuit protection device. This is a very robust and generous circuit protection. It seems to me a very prudent and responsible installation.

The last 2 sentences of that post is bad advice. Bypassing the master is good design in this installation.

My post was not referring to the surefly installation but to unprotected wires finding their way into the cockpit in general (actually another popular electronic ignition supplier supports this). Please read all the posts before taking my words out of context.
 
I am not a fan of putting EI products on the master buss. Too many things can short, requiring one to turn off the master due to problems. I have a master buss, an avionics buss and an ignition buss. Each has an SP3T switch that can connect to the L, R or both batteries. Master has traditional contactors. Others use relays. Nothing wrong with a switch or breaker in the EI supply circuit; Just find a way to shut down the master without taking out the ignition. If you still have a traditional mag, this is a non issue.

Larry
 
So continues power is only required to satisfy the certified installation, and will not adversely affect the ignition as long as the engine is off.

Pretty sure the only rule they were trying to satisfy was this one:

A device not installed never fails

Protecting the wire with the recommended 10a fuse at the battery seemed so obvious to me that I didn't bother mentioning it.

Or a fusible link...two crimps, otherwise all wire.
.
 

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Or a fusible link...two crimps, otherwise all wire.
.

What's the advantage of the fusible link over a standard fuse?

I'd think it would be harder to replace in the field should it fail for some trivial or easily remedied reason?
 
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What's the advantage of the fusible link over a standard fuse?

I'd think it would be harder to replace in the field should it fail for some trivial or easily remedied reason?

Given the power feed for my SureFly is less than 24" long and is carefully insulated and secured, what trivial or easily remedied failure would occur? If the power fuse (link) blows.....the SureFly internals have expired.
 
As luck would have it, I've got 230 hours on the tach, AND an impulse coupled mag requiring a 250 hour inspection. Good opportunity to upgrade to the Surefly.

Installation was plug and play awesome with utilization of the stock Slick harness, but I too ran into the issue of providing constant power. I didn't like the idea of having to run another line thru the firewall, down some conduit, to reach the rear battery, so tied into the fat wire coming into the starter contactor.

Pro: kept my power run at about 18 inches, didn't have to run to the rear of the plane, easier install

Con: Is NOT constantly supplied with power - requires battery master to be on to energize the fat wire (battery contactor in the rear).

I was willing to accept this because I have another magneto that will continue if for some reason I have to shut down the battery. Was not worried about draining the battery.

Not all will accept this, and I wouldn't if I had two EI systems dependent on power.

Phil
RV10, built/flying
Bountiful, UT
 
Fuse or fusible link?

Given the power feed for my SureFly is less than 24" long and is carefully insulated and secured, what trivial or easily remedied failure would occur? If the power fuse (link) blows.....the SureFly internals have expired.
Good points. I did find the factory supplied fuse housing was handy for interrupting power (remove fuse) for the timing check. A fusible link would require a terminal removed, not a big deal but a hassle if things are tight. Because of a thoughtful IA, we’ve got a pigtail on the timing terminal, it made timing check easy, in an otherwise tough area to access. Some might think the timing doesn’t change, right or wrong, I want to check it.
My Surefly is on a Cessna. For the RV, I’ll take the EI that can make its own power, even if it hasn’t cleared the FAA hurdles.
 
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