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Ford edis with megajolt

My statement:
Originally Posted by rv7charlie View Post
If you think about it, a modern battery is extremely reliable. If maintained properly, it's probably the most 'reliable' component in the plane. So why are there two?
Batteries have been known to take an unexpected dump, especially some lithium ones. With a battery dependent ignition system, you lose a single battery, the engine stops. That's a good reason for a second one in my view. I have personal experience in this regard...

We never recommend anyone running two EIs in an aircraft to use a single battery.
Boy, the interwebs are a tough place to communicate.

1st, my mistake for not specifying 'modern *sealed lead acid* battery'. The various lithium chemistries are still a big wild card to introduce, especially when they interact with another other new variable.
Now that that is out of the way, aren't you making my point? If redundancy is highly recommended, shouldn't all single points of failure that negate the redundancy be eliminated, as well? If you'd quoted the rest of that post, you'd have seen:

Something that comes up all the time on the Aeroelectric List is not designing for reliability (which should be a given), but for redundancy. If you think about it, a modern battery is extremely reliable. If maintained properly, it's probably the most 'reliable' component in the plane. So why are there two?

That last question was rhetorical; Of course you want redundant power. But if the non-redundant delivery is the failure point, then it's just dead weight. (Pardon the pun.)

Last, I'm more comfortable with redundant generating systems (which will weigh less) with redundant paths , than with redundant batteries, which still have (highly variable) endurance limits even if they don't actually fail. Yes, you can do both, but should we add an extra set of wings, as well? (Rhetorical question.)

Charlie
 
Even with two alternators? I have a Plane Power and an SD8.
Yep, I have cleaned the negative terminal of corrosion (green) on my Odyssey PC680.

Three thoughts.

One, I'm going to give IGN2 a separate ground, as corrosion could cripple the ground path at the main battery negative terminal.

Two, I never considered corrosion, as I've never seen it on any AGM battery. Yet it exists. Peer review is good.

Three, regarding dual alternators or dual batteries; as we've seen (again), God is in the details.

NOTE PLEASE: I much appreciate the peer review of specific wiring. However, let's not steer this thread off into general battery and alternator debate. It's about EDIS and Megajolt, ok?
 
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Ignition #2 now installed. Useful data...

Current draw, per ignition, EDIS and MJ/E combined:

Switch on, engine not running, 90 mA

1200 RPM, 520 mA

1800 RPM, 800 mA

2700 RPM, 1.08 amp

Single ignition drop, 25~30 rpm
 
Considering all the stuff in the prior pages about the drive speed of a six cyl mag/rotor assembly, I suspect your mag hole trigger may not be a viable option for me???

I also have a 6 cyl engine I'd like to try this with. I'm looking at putting one trigger on the front of the crank, and one on the rear for added safety. By my calculations an 18 tooth mag drive gear would bring the 1:1.5 drive ratio on the 6 cyl engines back to 1:1 while using a standard mag shaft. Such a gear would need to be custom made for our applications. Cut stock gears won't do it. These would need to be ground and case hardened.

I believe the existing 6 cyl mag gear is 10 DP, 20 PA. I can have them made using EN36A for approximately $250 if we order 10 at a time.

I have a design for a suitable housing to offset the larger gear in the case and allow timing to be adjusted. If there is sufficent interest I may post some Solidworks images of what I have mocked up.
 
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I also have a 6 cyl engine I'd like to try this with. I'm looking at putting one trigger on the front of the crank, and one on the rear for added safety.

As a thought exercise, explore trigger location risk. Feel free to add to the lists.

Crank trigger:
1. belt breakage may take out reluctor bracket or wiring

Mag hole trigger:
1. torsional vibration issues
2. bearing issues
3. oil seal issues
4. machining error
5. component joining issues

What else?

Yes, I went with rear triggers, and I'm not going to say you shouldn't. On the other hand, I think the risk factors are higher with mag hole triggers, an inescapable result of parts count. The six cylinder compounds that problem, by adding custom gears and housings, and a somewhat higher chance of torsional vibration issues at some unknown RPM. They don't put rubber drives on 6-cyl mags without reason.

Even given the lower torsional risk of the 390 (short 4-cyl crank with pendulums), one key reason I've been flying an EDIS/Slick combination for a year was the opportunity for long term examination of the trigger unit drive gear. It was out for inspection last week.

If the single risk of a front trigger is belt failure (are there more?), a fella could turn out one heck of an armored shield with a a TIG and some 4130 plate.
 
As a thought exercise, explore trigger location risk. Feel free to add to the lists.

Crank trigger:
1. belt breakage may take out reluctor bracket or wiring

Mag hole trigger:
1. torsional vibration issues
2. bearing issues
3. oil seal issues
4. machining error
5. component joining issues

What else?


If the single risk of a front trigger is belt failure (are there more?), a fella could turn out one heck of an armored shield with a a TIG and some 4130 plate.


OR ... you could have no front alternator , just a vac pump pad mount alternator and keep the nose ultra clean, light and simple on a day VFR only RV.
 
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A bit more work...

With a bit more work Dan, you could put some permanent magnets in the flywheel and make a brushless alternator out of the flywheel. That would also get rid of the drive belt on the front end.
 
If you've already got a mag drive sensor for one ignition, why not use a crank trigger for the other, and consider the redundancy taken care of?

I did put a guard over the CAS on my Wankel installation, but I it's worth mentioning that I can't remember the last time I had an alternator/fan/water pump belt failure, on a car or a/c. Cars I can understand; most have spring tensioners that maintain proper belt tension, but I've had great luck, even with a/c engine belts. Current belt tech is pretty impressive.

Charlie
 
As a thought exercise, explore trigger location risk. Feel free to add to the lists.

Crank trigger:
1. belt breakage may take out reluctor bracket or wiring

Mag hole trigger:
1. torsional vibration issues
2. bearing issues
3. oil seal issues
4. machining error
5. component joining issues

Dan,

I don't disagree there are some considerations with the rear pickup and its engineering. However, I think you have somewhat understated the risk associated with two pickups on the crankshaft as anything that gets loose in there may well destroy both systems.

I am not overly concerned if the rear mounted system fails (and doesn't compromise the engine itself). Simultaneous failure of both pickups could result in a fatal accident.

The group may find the following accident report useful.

http://www.atsb.gov.au/media/5341498/AO-2013-221 Final.pdf
 
Dan,

I don't disagree there are some considerations with the rear pickup and its engineering. However, I think you have somewhat understated the risk associated with two pickups on the crankshaft as anything that gets loose in there may well destroy both systems.

I am not overly concerned if the rear mounted system fails (and doesn't compromise the engine itself). Simultaneous failure of both pickups could result in a fatal accident.

The group may find the following accident report useful.

http://www.atsb.gov.au/media/5341498/AO-2013-221 Final.pdf


It seems that we are going down the familiar rabbit hole of trying to guard against the mere possibility of failure, rather than evaluate the probability, as Dan is wisely suggesting. After all, the entire accessory gear train in a Lycoming depends on a single 5/16 bolt securing the crank gear- yet we don't give that much thought. So back to Dan's point, aside from a belt coming loose (which is easily guarded against), or bad design/maintenance (as the Glassair accident suggests), what is the probability that something can "get loose in there" (behind the ring gear) that wouldn't cause engine stoppage anyway?

I'm not saying it can't happen, and I'm not saying that I'm not blind to my own logic/justification, but I'm not seeing a higher risk with a properly designed and maintained front pickup system.
 
After all, the entire accessory gear train in a Lycoming depends on a single 5/16 bolt securing the crank gear- yet we don't give that much thought.

To compare the reliability of a home brewed, one of a kind crankshaft position sensor installation with a component that is the subject of numerous SBs and has 60+ years and millions of hours in service doesn't really work for me.

This whole thread started with Dan building a rear mounted pickup. Presumably he had his reasons despite both of us acknowledging the additional complexity.

We all have different views on this stuff and that's fine. My personal design goal is zero probability of a single failure taking out both ignitions.
 
My personal design goal is zero probability of a single failure taking out both ignitions.

Go for it. I can see a little higher risk per trigger, but an argument for low risk of double failure makes sense.
 
Maybe I missed it..

Maybe I missed it in an earlier post...

Dan.. I see pics in post #4..
What High voltage power pack are you using? ie. What year/model car/truck did it come from?
Did you make your spark plug wires or did you buy some off the shelf?
What spark plugs are you using? Gap?

I know you use a IO390. Do you feel that these parts would work well for an O360 lycoming? I saw that Kirk has a 360. Are you guys running the same power pack, wires and spark plugs?

Thanks.
 
Dan.. I see pics in post #4..
What High voltage power pack are you using? ie. What year/model car/truck did it come from?

Follow the link in post#4 and read the Megajolt manuals. The popular EDIS-4 module seems to be a new or used Motorcraft DY-630, Module F1CZ-12K072-A, taken from a 91 to 96 1.9L Escort or Tracer. Also Standard Motor Products LX239.

I assume "power pack" means coils? There are two Ford choices, early and late, plus dozens of others that are compatible. Zillions of sources.

Did you make your spark plug wires or did you buy some off the shelf? What spark plugs are you using? Gap? I know you use a IO390Do you feel that these parts would work well for an O360 lycoming?

Made up plug wires. Components here: http://www.kingsborne.com/

I use long reach plugs, so they will be different. Everything else is the same.
 
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Update for those following along.

The wiring shown a few posts previously has one sneaky failure mode. If the path between the main contactor and the second battery should become open for some reason (broken wire, failed terminal, fusible link or diode burns open), the ignition would continue to operate normally...until the battery ran dead. It's not a critical failure; the other ignition would be unaffected. However, the "mag drop" is so small that a pilot might not notice. The only other clues might be a change in EGT and perhaps some slight roughness if LOP at the time.

It needs an voltage monitor, something to draw attention to a loss of alternator voltage on the second ignition. The EFIS already monitors the main bus, so that's covered. My GRT Sport doesn't have an available input for the monitor task, so I went looking for a suitable stand-alone device. This one fit the bill, and it was a whopping $4.59, delivered:

http://www.tomtop.com/modules-219/p-e1021.html

Voltage%20Monitor.jpg


The digital display is for setting the upper and lower voltage limits, using the three buttons. It's a "set and forget"; the board is mounted in a sealed box under the panel. If line voltage goes over or under the limits, it closes the relay and sets off a buzzer. I installed a flashing LED under the #2 ign switch, and set the lower limit at 12.8V:

Low%20Voltage%20LED.jpg


Function is dirt simple. The LED flashes when the ignition switch is moved to ON, prior to engine start, as battery voltage alone is below 12.8. That's the self test. It stops flashing when the alternator comes on line after start. If it flashes in flight, there is something wrong. The buzzer can't be heard in flight, but it's a perfect volume to warn that I've left the ignition on after shutdown, a nice bonus.
 
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Thank's for that link to voltage warning board.

I've order one for the 8 and one for the 9A.

Seems like a great safety feature if using a non standard battery.

Easy to implement as adjustable over-voltage 'Crowbar' with SCR.

Roger Bloomfield
 
Update for those following along.

The wiring shown a few posts previously has one sneaky failure mode. If the path between the main contactor and the second battery should become open for some reason (broken wire, failed terminal, fusible link or diode burns open), the ignition would continue to operate normally...until the battery ran dead. It's not a critical failure; the other ignition would be unaffected. However, the "mag drop" is so small that a pilot might not notice. The only other clues might be a change in EGT and perhaps some slight roughness if LOP at the time.

It needs an voltage monitor, something to draw attention to a loss of alternator voltage on the second ignition. The EFIS already monitors the main bus, so that's covered. My GRT Sport doesn't have an available input for the monitor task, so I went looking for a suitable stand-alone device. This one fit the bill, and it was a whopping $4.59, delivered:

http://www.tomtop.com/modules-219/p-e1021.html



The digital display is for setting the upper and lower voltage limits, using the three buttons. It's a "set and forget"; the board is mounted in a sealed box under the panel. If line voltage goes over or under the limits, it closes the relay and sets off a buzzer. I installed a flashing LED under the #2 ign switch, and set the lower limit at 12.8V:



Function is dirt simple. The LED flashes when the ignition switch is moved to ON, prior to engine start, as battery voltage alone is below 12.8. That's the self test. It stops flashing when the alternator comes on line after start. If it flashes in flight, there is something wrong. The buzzer can't be heard in flight, but it's a perfect volume to warn that I've left the ignition on after shutdown, a nice bonus.



Dan,

Your diagram depicted immediately above in white over black shows a relay and a volt meter between the diode and smaller battery.

Is the relay on the blue (Tomtop) circuit board shown above the same relay as the one depicted in the white over black diagram?

Is the "voltmeter" depicted in the white over black diagram actually the LED you have mounted under the switch labeled "Mag 2"?

How's it all working? Anything you'd change or do differently.

I am preparing to install dual EI (SDS) and I'm interested in using this concept.

Thank you,
 


Dan,

Your diagram depicted immediately above in white over black shows a relay and a volt meter between the diode and smaller battery.

Is the relay on the blue (Tomtop) circuit board shown above the same relay as the one depicted in the white over black diagram?

Is the "voltmeter" depicted in the white over black diagram actually the LED you have mounted under the switch labeled "Mag 2"?

How's it all working? Anything you'd change or do differently.

I am preparing to install dual EI (SDS) and I'm interested in using this concept.

Thank you,

No, it's an additional check feature. You've pulled up a diagram from another thread. The voltage monitor can be seen at the lower left, parallel with IGN2. It warns if the small IGN2 battery is not being charged.

The relay, push-to-test switch, and the voltmeter (center of the diagram) allow a check of the battery itself, in flight. Pushing the button disconnects the secondary battery from the rest of the electrical system and displays its voltage under IGN2 load. The voltage monitor will light its panel LED at the same time, since the voltage will drop below 12.8V.

The inexpensive voltage monitor has been flying since early this year. I have collected the parts for the push-to-test-the-battery circuit, but have not yet installed it.
 
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Frank there is a guy at Kars Rideau Valley Airpark (just south of Ottawa right on the Rideau River) named Jim Scoles who is running the Megajolt with a Ford EDIS module in an O-200 powered Tailwind. I'm sure if you dropped in to see him he would be happy to show it to you.
 
Annual time, always an opportunity to catch up on some projects.

Last year I installed a voltage monitor (see a few posts back) based on a $5 board from China. It continues to work great, flashing a light and sounding a aural warning if IGN2 power falls below a preset threshold. It would let me know if the small secondary battery dedicated to IGN2 is not being charged, as the alarm threshold is set at 13V.

However, there remained the possibility that the small battery may not have very much storage capacity, or otherwise had developed a fault. After all, the whole point of installing a dedicated battery is to have some flight time on that ignition after shutting down the aircraft electrical system. Simple approach to the problem is a load test, i.e. check the battery voltage under load.

With the engine running, pressing the test button disconnects the IGN2 battery from the charging source, and sends power to a miniature panel voltmeter. The display is battery voltage under load.

This photo taken with the engine not running. It was sitting right on 12V while powering IGN2. Sorry, the button is under my index finger.

Backup%20BatteryTest.jpg
 
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Dan,

Thanks for posting your findings on your circuit.

Have you established probable cause for the diminished storage capacity of your small battery?

Your voltmeter placement and button look well placed. I like your labeling.

Thanks,
 
Have you established probable cause for the diminished storage capacity of your small battery?

I have no reason to believe it is diminished. It's a tiny little 3AH battery running with a 1 amp draw, so 12V under load sounds about right. Anyone have a reason to believe otherwise?
 
If I'm reading this correctly, when you use the press-to-test function you are getting the ignition battery alarm (because it trips at 13V to signal loss of its charging source) AND you're able to read the instantaneous voltage on the ignition battery. If this interpretation is correct then 12.6V certainly looks normal for an instantaneous test after disconnecting the charging source.

Ingenious.

The only possible alteration which might be considered would be to have a second locking position on the press-to-test switch in which the contacts are held closed so you can more easily perform a longer-term load test on the ignition battery. I suggest a locking toggle only because it would require a very conscious effort to more permanently isolate your ignition battery from its charging source.

I really like the way this is set up, especially because it uses the disconnect relay in its Normally Open (relaxed) state for normal operations. Pretty hard to improve on this circuit.
 
If I'm reading this correctly, when you use the press-to-test function you are getting the ignition battery alarm (because it trips at 13V to signal loss of its charging source) AND you're able to read the instantaneous voltage on the ignition battery.

Correct.

The previously discussed voltage monitor board actually has a built-in voltmeter, used for setting the alarm limits. It also displays monitored voltage when not in the "set" mode, but it's awkward to make it a nice looking panel display. Besides, I wanted to be able to disconnect the IGN2 battery from the main battery for the load test.

If this interpretation is correct then 12.6V certainly looks normal for an instantaneous test after disconnecting the charging source.

That 12.6 is no-load. It's about 12.0 given a 1 amp draw.

UPDATE 2019: The little Motobatt AGM battery was ultimately deemed defective. As noted, its voltage under load was poor when disconnected from the alternator. The kicker was that over time, it started causing voltage fluctuations detectable by the voltage monitor board. I'd get random in-flight buzzer and LED indications for just a second or so. Checked all other components and connections, with nothing found, so I replaced the battery...after which there were no more odd indications. I think the battery had a cracked internal connection.

Ingenious.

Thank you.

The only possible alteration which might be considered would be to have a second locking position on the press-to-test switch in which the contacts are held closed so you can more easily perform a longer-term load test on the ignition battery.

Yeah, I was planning to see how long IGN2 would actually run on its own little battery. The RV-8's side switch console is open on the bottom, and the switch is just a ground, so for a one-time test all it takes is a jumper wire and two alligators.
 
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EI Internal Power

Hey Dan,

Forgive my ignorance, I am not familiar with your EI....and I am sure you have already considered this..... Are the EI internal power circuits electrically isolated from each other?
 
Hey Dan,

Forgive my ignorance, I am not familiar with your EI....and I am sure you have already considered this..... Are the EI internal power circuits electrically isolated from each other?

Two entirely separate ignition systems, independently powered from two batteries. I don't think anything short of an EMP pulse is going to shut down both.
 
I have no reason to believe it is diminished. It's a tiny little 3AH battery running with a 1 amp draw, so 12V under load sounds about right. Anyone have a reason to believe otherwise?

I wouldn't be concerned with 12.0, but I would expect mid 12's. Given that the battery just came off of a 14V float and the load is relatively light (.33AH), I would expect around 12.5 for a new battery.

Larry
 
If this interpretation is correct then 12.6V certainly looks normal for an instantaneous test after disconnecting the charging source.

A no load test straight off a float charge should be above 13 volts. A fully charged lead acid battery, after stabilizing, should be around 12.8.

Larry
 
Time to revive the EDIS discussion.
I just ordered the new Mk-2 Megajolt, promised shipping April 20, 2018.
https://www.autosportlabs.com/product/megajolte-mk2_crank_fired_ignition/
A pull from the link:

"Improvements in the new Megajolt/E MK2
The new Megajolt/E MK2 has been evolved to add the features you’ve asked for, while making the system more robust and compact:

Hard Rev Limiter included!
USB interface for ease of use: No drivers needed for Windows 10; easy to install drivers for previous versions of Windows.
Status LEDs for RPM and Ignition Advance signals to aid in diagnostics
Improved and ruggedized power supply and enhanced transient protection on inputs
More compact: Just 85 x 85mm
100% compatible with previous generation Megajolt/E and Megajolt Lite Jr V4 – drops right in!"


Dan, I sent you an email requesting the waterjet cutting files for the two types of trigger wheels, if you are still offering?
I've let this project slip while other ones somehow took over, but I'm looking at a couple of old Bendix magnetos that want some 500 hour $$$, so now would be a good time to invest those same $ in a (presumably) more permanent solution.
 
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Dan, I sent you an email requesting the waterjet cutting files for the two types of trigger wheels, if you are still offering?

You're welcome to them, but they must be on my hard drive at the office. Can't find them here at home. I'll look later today.

In the meantime, I know I sent copies to Mike Starkey and Graham in Oz (Airtractor8).
 
Scott,

I'll revise the drawing for the internal ring, and send one with both the original diameter and the slightly increased OD Graham preferred.
 
Thanks Dan;
I took the file Graham sent me to a local waterjet shop, but the proprietor backed out on the old 'Liability' excuse when he asked me what it was for...I just couldn't lie.
Also, he suggested that .015" was his tolerance limit, so I'll try a few other local shops for better when I get a few days off. I think this guy is more into art than mechanics.
My work/airplane mentor just got the EDIS bug, so I brought my demonstrator rig to his hangar and we put it on his lathe. I love how the pickup can be about 1/4" away from the trigger wheel before spark is lost. I made sure the trigger wheel was running crooked too. :rolleyes:
 
Is there a page with images on how the pickup wheel is mounted to the flywheel? Images on early pages in this thread are no longer available.
 
I received the Megajolt/E controller yesterday. It is the new (just released!) Mark II version, and has been upgraded including a USB mini port for programming and a new smaller case.
This morning, I'm reading the instructions, and particularly the programming portion:
https://wiki.autosportlabs.com/MJLJ_V4_Operation_Guide
I'm wondering if anyone using the Megajolt control would like to share their programming or comment on programming preferences?
Right off the top, it looks like the ten RPM bins could be divided across 4000 RPM instead of 10,000RPM.
The Rev limiter is an option not available with magnetos....and the ignition advance could be programmed to retard at an excessive RPM as well.
Cockpit control of advance (could be used for leaning) is available via an auxiliary input, or could be automatic based on a thermistor (oil or cylinder temp?)
 
Right off the top, it looks like the ten RPM bins could be divided across 4000 RPM instead of 10,000RPM.

Try:

1000
1500
2000
2100
2200
2300
2400
2500
2600
2700

It extrapolates between bins, so the big jumps down low don't matter.

The Rev limiter is an option not available with magnetos....and the ignition advance could be programmed to retard at an excessive RPM as well.
Cockpit control of advance (could be used for leaning) is available via an auxiliary input, or could be automatic based on a thermistor (oil or cylinder temp?)

I'm switching to get the hard rev limiter, one box now and one later (the conservative approach with new hardware).

The dual map function is a single wire, ground to activate, so two brains can be tied to the same cockpit switch without risk. It's a single flip to change from a ROP map to a LOP map. (WRONG...see next post)

I suppose it could be rigged to un-ground based on temperature or something, but KIS has a lot of merit. Since we can map 100 points (RPM x MP), there is no virtue in a hardware based return to the ROP map just for high manifold pressure. Enter retarded timing values for the high manifold pressure area of the LOP map. That way, if you go to full throttle with the LOP map engaged, who cares? We don't use that part of the map up high in lean cruise anyway.

It is possible to enter a timing offset based on an external input, via pin 9.
 
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Previously I wrote...

The dual map function is a single wire, ground to activate, so two brains can be tied to the same cockpit switch without risk. It's a single flip to change from a ROP map to a LOP map.

...which is true enough, when both ignitions are powered. What I didn't realize was that with one ignition OFF, it apparently becomes a path to ground for the other ignition, even with the map select switch open. Flip one to OFF, and the other changes to map 2.

The way my maps are configured (all high power settings are low advance), it doesn't seem to make any difference. However, it could with a different map. So, going forward I'd suggest wiring the map select grounds through separate switches, or through a DPST rather than ganging them on a SPST.
 
Current EDIS4

I?m building a bench mock-up of a megajolt/EDIS4 ignition system to get to know it before laying out more concrete plans to put it in an airplane. What current should I plan for for the ignition when running? I?m setting up for 20A on three separate feeds, but I can?t sustain it indefinitely on my power supply Thanks.
 
Thanks....

Thanks Dan, I might have asked the wrong question. In the same scenario, what is the current draw of the coil?
 
Current

Dan, do you recall how you measure current? Did you use a scope and picked up the individual coil dwells or some other fast instrument that would give an average value? I ask because I may be on the opposite side, where my admitadly Amazon shunt based ammeters I have in my bench setup are showing much higher current flow. At about 1000 rpm, I?m recording ~2A, 2400 rpm is ~4.5A., it?s linear with rpm, which makes sense. I?m guessing my setup is showing peak current snapshots. Running at 2700rpm, neither the coil nor EDIS have more than 35F temperature rise over ambient in still air, so it seems efficient.

Overall, the Megajolt/EDIS/coil setup runs really well. There are some quirks to the Megajolt software, but the system is simple to execute.

I have a vac pump and the tone ring/timing wheel on variable speed drives, an old school timing light to verify reported advance. I can isolate the Megajolt, dropping the EDIS in to backup, and have the two map switch installed. I?m going to work with it some more, but I think it?s going in the airplane. The tone wheel may be tricky. I also need to decide what to do about the D3000.
 
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