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PMag Questions

bkervaski

Hellloooooooo!
Testing
I have two questions for PMag owners:

1) Do you check the generator at run-up every flight or is it just a periodic check? I'll have mine on breakers since it's a retro and I don't want to rework my panel.

2) What are you finding at the 100 hour inspections?

Thanks!
 
1. I do the internal generator check maybe twice a year. The pMags are on pull breakers. Don't be surprised if the internal generator works down to 750 RPM or so.
2. 100 hour checks - nothing ever found (1200 hours on the pMags)

Carl
 
I do the generator every run up. Never had an issue.

100 hour inspection, never found anything. Almost 500 hours.

-Dan
 
1) Do you check the generator at run-up every flight or is it just a periodic check? I'll have mine on breakers since it's a retro and I don't want to rework my panel.

Not much point in having a p-mag if you're not sure the internal generator works.

I have found a dead one during a pre-buy.
 
I perform the generator check before every flight.

I had one fail at around 500 hours and the engine never skipped a beat. The only way I found it was in the preflight for the next flight.
 
P-Mags on breakers vs VP?

Op brings up a good point. I ran P-Mags on my -9A for many years which had separate panel mounted breakers. In planning my new build I am inclined to retain that configuration vs putting them on the Vertical Power bus for quick access to pre-flight testing . . . any thoughts on this Bill R?
 
Op brings up a good point. I ran P-Mags on my -9A for many years which had separate panel mounted breakers. In planning my new build I am inclined to retain that configuration vs putting them on the Vertical Power bus for quick access to pre-flight testing . . . any thoughts on this Bill R?

Mark,

You can still run the P-mags through your VP bus and install a three way switch for testing. (I have pullable breakers plus the three way switch. Up is ungrounded and powered, middle is ungrounded and unpowered, and down is unpowered and grounded.)

Here is how I perform my pre-flight check before every flight. It takes longer to read than perform.

pmag%20preflight.jpg


Here is an old picture of the panel, the switch placement has remained the same through three iterations and will remain the same as I plan the next panel upgrade.

Switch%20Placement.jpg

(You can see I still hadn't cleaned up the wiring when this picture was taken.)
 
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I have spring toggle switches (push to open) on PMag power (as well as breakers) and check the internal generators independently at run up on every flight. I?ve never had an internal generator failure in 500 hours.
 
We have dual P-Mags on our 7 - original fit since 2010.

I do a dead mag check every month, we do an inspection at annual when we change the plugs - whooo hoo, $7 a piece at O'Reillys ;)

Only time we had an issue was when someone timed them like dumb mags. Holy carp, that backfire was spectacliar !

Fit 'Em, Fly 'Em, Enjoy 'Em.

Bring on the 6 version into production.

:D
 
I do the generator check on every run up and have never had an issue. Dual P-Mags with individual circuit breakers and normally closed push to test buttons. I also do 100 hour inspections and have never found anything wrong. 450 hours and counting.


:cool:
 
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I think I like the normally closed, momentary switch configuration for testing the generator function. That seems to me to be a good solution. My thinking is normally the power is connected but during run-up I can do the generator test. A normally closed push button would work, but I'll stick with Honeywell toggles.
 
MAGs and PMAGs also hardly ever fail but we still do check at each run up before each flight, so the failure rate ought not to be a guide as how often we check them.

I do a MAG check as well as power check at each run up, so far has not had any failure with PMAG and my standard 100 hours has been just checking for what is recommended, play in the shaft and so far has not had any issues. nearly 600 on the 7A and now about 70 hours on the 14A
 
I had dissimilar component failures of both PMags at the same time. Neither caused loss of ignition. One PMag had a phase failure of the internal generator (alternator?) and the other had excessive radial and axial bearing play - which led to erratic timing. The PMags had less than 100 hours on them. They were an early build version, but I had sent them to Emag for upgrades prior to first flight.

I?ve since installed an EI32 Commander to monitor and I check the internal generator as part of the run up check. I have lever lock switches with a momentary ?up? position which removes ships power from the PMag.
 
I have dual P-mags with a pull breaker to each, can you guys tell me the best way to do the mag generator test!

1- bring RPM to 1600, than pull both breakers? Leave the key on Both?
 
My PMAG is on a 3-way switch, one for each L/R. The down position is "off". There the ignition is powered, but the p-lead is off so it will not run. Mid position is "run" and that is with the p-lead on for running. Up position is "Test" and that removes power to the ignition to test it running off of ship power, but the p-lead is still on for running. "Test" is spring loaded so it goes back to "run" after a test.

When I start up the master is on, then both ignitions to "Run". Start, etc.....

On pre-flight run-up I set 2000 RPM. L ignition to "off", watch the engine run on the other ignition with a slight speed drop. While running L off, R to "test" so now the right is solo on it's own battery. Return R to "run" then L to "run". Repeat on the other side.

I think this tests the important parts of the system. I don't think it is needed to pull the breaker to it to get this done. It tests both single PMAG running on their own power each preflight.
 
I have dual P-mags with a pull breaker to each, can you guys tell me the best way to do the mag generator test!

1- bring RPM to 1600, than pull both breakers? Leave the key on Both?
FWIW with dual P-mags, individual circuit breakers and individual (normally-closed) push to test buttons.

e7e2.jpg


364.jpg


1 - Before engine start I push each test button to confirm they are actually disconnecting ship's power from the mag. The LMAGST and RMAGST indication on my DYNON EMS should turn RED while the button is pushed.
2 - After engine start I set the power to 1,000rpms then push each test button to confirm the P-mags operate without ship's power. There should be no change whatsoever to engine operation.
3 - I set power to 1,800rpms and do a normal mag check showing a 50-75rpm drop while running on one mag.

This procedure is part of my check list.

:cool:
 
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My config, a flight failure and checklist change...

I have the Pmag on its own CB and a 3 position toggle switch;
Up - UNGROUNDED / POWERED
Middle - UNGROUNDED / UNPOWERED
Down - GROUNDED / UNPOWERED
I like having all the switches in the UP position when they are normal for flight instead of in the middle like would be if using a momentary switch.

This setup is good for doing the run up check before every flight (which I do), but there is no switch configuration which puts you into config mode to set the timing. So I added an extra lead which runs from a ground block on the firewall through a spade disconnect (the water tight ones so it can't ground anywhere when it is disconnected) and to the Pmag to get me to the powered but grounded configuration when I want to set the timing.

I have one Pmag and one impulse mag in my Velocity and had an interesting failure the other day; I landed and during the rollout the engine died and couldn't be restarted. I coasted across the hold line... Strange with two ignition systems.

As part of the install/setup, I knew that the Pmag wouldn't generate its own power reliably below 800 RPM. I found the 12v wire had come out of the connector in flight. After fixing that, I then discovered the magneto was incapable of running the engine on its own below 700 RPM! Sent the mag out to the shop and ended up having to get a new magneto. Both systems worked fine prior to flight with only 80 RPM difference during the run up at 1600 RPM.

The mag shop said it was good idea to do a low RPM pre-flight mag check as well. So I have added that to my checklist. The Pmag can mask a faulty Slick (i.e., if the Slick dies in flight, you'll never know it).

(epilogue: I know mag should be sent out for repair following prop strikes, which this engine didn't have. However, this engine was oversped by the previous owner, torn down, inspected and reassembled by a reputable shop. However, the mag was never checked out before reinstalling. I think the overspeed may have damaged the mag... I have heard that they can be damaged above 3000 RPM.)

If you didn't see it a while back... there was an RV in France which had 2 Pmags installed (albeit improperly) and while turning on final neither had 12v power and both Pmags (and the pilot) died due to the low RPM. Make sure your Pmag is generating power during the run up and know below what RPM it won't.

MTCW
 
One more option

My setup uses master buss for both Pmags. It was wired before all the discussions about 3 pole switches and NC push buttons to test self-gen function. So, I periodically cut master power before run-up mag check. This has the negative impact of rebooting anything powered by the master buss.

A flight school owner/contract pilot once told me to test mags while taxing to the hanger, so you don?t discover the problem with a plane loaded with paying passengers. After following the discussions on clever switches and extra buttons, I thought of this:
What if you adopted a shut-down protocol to kill the master ( and dependant loads in your order of preference), then test each Pmag, then idle cutoff. This would even heat the plug insulators clean of lead (if you use it).
 
Inline breaker ?

Carl, perhaps I misspoke. Now that you asked, each Pmag is on its own fuse and switch from the battery solenoid main buss that is powered by the master switch. Pmag switches: Down is grounded and up is 12v fused. The easy fix is NC push buttons, but I don't work on my 3B unless necessary in order to keep focus on my -4 build. I am encouraged to use breakers only on ALT field and Flaps that are known to experience excursions that are not symptomatic of a terminal issue that should not be reset in flight.
 
...

2) What are you finding at the 100 hour inspections?

Thanks!

Anyone find anything at the 100 hour inspection? I have one coming up, and it's not really that clear what to look for. The manual says this:

PmagManual LC114.28 p23 said:
Remove ignition and examine shaft and drive gear condition. Note: Ignition disassembly is not necessary (and if done may void your warranty). Look for excessive play (lateral and axial). Shaft rotation should be free, with no catching, flat spots, or grinding. The shaft on “P” models (with internal alternator) will have a push-pull rippling effect as the shaft turns and the permanent magnets pass the rotor poles. This is normal and expected. If a P model ignition does not have this magnetic ripple, the unit requires additional (shop) service.
Seems straightforward, but wanted to check with the brain trust beforehand, since I've seen them when they were new, but not 100% sure I would recognize a problem by wiggling the shaft.
 
Shaft play

Mickey,

At my last conditional inspection in February I had one of my pmags where there was lateral play in the shaft that amounted to about 1 mm total from side to side, maybe even a little less. The other pmag had absolutely none. I spoke to Brad about it over the phone and decided to send both units in. At the time, I had been flying the plane almost two years and had just over two hundred hours on it and had not had any problems with either unit.

When I got them back, the shafts on both units were rock solid. Brad didn’t say if there was any acceptable tolerance with shaft play, but convinced me that it was better to have them looked at than run the risk of internal damage or failure if shaft lateral play were to increase. Other than obvious repairs, I don’t know what all they check or service when they receive units in from customers, but in my case they also updated the software to version 41. I was also concerned about any possible damage due to excessive heat as the temp stickers on both units had tripped at just under 200 degrees.

I have to admit that pulling the pmags out far enough to conduct this inspection every year is a bit of a pain, but I’m happy with their performance so far and the customer service from Emagair has been excellent.

J Baker
RV8
 
Mickey,

At my last conditional inspection in February I had one of my pmags where there was lateral play in the shaft that amounted to about 1 mm total from side to side, maybe even a little less. The other pmag had absolutely none. I spoke to Brad about it over the phone and decided to send both units in. At the time, I had been flying the plane almost two years and had just over two hundred hours on it and had not had any problems with either unit.

When I got them back, the shafts on both units were rock solid. Brad didn’t say if there was any acceptable tolerance with shaft play, but convinced me that it was better to have them looked at than run the risk of internal damage or failure if shaft lateral play were to increase. Other than obvious repairs, I don’t know what all they check or service when they receive units in from customers, but in my case they also updated the software to version 41. I was also concerned about any possible damage due to excessive heat as the temp stickers on both units had tripped at just under 200 degrees.

I have to admit that pulling the pmags out far enough to conduct this inspection every year is a bit of a pain, but I’m happy with their performance so far and the customer service from Emagair has been excellent.

J Baker
RV8
Thanks Jim - this is very helpful. I would not have thought that 1mm shaft play is enough to take them out of service, but if that's what Brad says, I'll of course follow his advice. I'm also really happy with the performance of these pmags.
 
Doing my annual condition inspection at 981 hours. I have pulled off both P-mags and on my right one, there is more play in the bearings than I think might be acceptable. The left one has just a real tiny bit of play, but you can definitely tell it isn't completely and solidly rotating without any bearing play.

The maintenance guide doesn't give any specifics for bearing tolerances. It simply says the following:
"Look for excessive play (lateral and axial). Shaft rotation should be free, with no catching, flat spots, or grinding."​

I took a short video of the play in the right P-mag here.

How much play here is "excessive"?
I don't recall ever having this much play in previous inspections.

I had the P-mags firmware updated and gone over in 2018 ago when I had around 550 hours on them.
 
That looks like it should be sent in and fixed up to me, but hey, why not provide the link to the video to Brad at Emag and let him judge?
 
Doing my annual condition inspection at 981 hours. I have pulled off both P-mags and on my right one, there is more play in the bearings than I think might be acceptable. The left one has just a real tiny bit of play, but you can definitely tell it isn't completely and solidly rotating without any bearing play.

The maintenance guide doesn't give any specifics for bearing tolerances. It simply says the following:
"Look for excessive play (lateral and axial). Shaft rotation should be free, with no catching, flat spots, or grinding."​

I took a short video of the play in the right P-mag here.

How much play here is "excessive"?
I don't recall ever having this much play in previous inspections.

I had the P-mags firmware updated and gone over in 2018 ago when I had around 550 hours on them.

Lets us know what you find out from emag.
 
Doing my annual condition inspection at 981 hours. I have pulled off both P-mags and on my right one, there is more play in the bearings than I think might be acceptable. The left one has just a real tiny bit of play, but you can definitely tell it isn't completely and solidly rotating without any bearing play....


...I had the P-mags firmware updated and gone over in 2018 ago when I had around 550 hours on them.

To be clear, the P-Mags have a total of 981 hours on them? And 431 hours ago (at 550 hours) they were serviced to include new bearings?

Just trying to get some data points. Keep us posted!
 
Both of the videos above appear to contain excessive play. I pull mine every 100 hours and both of mine have 0 play compared to the ones in the videos. Mine just passed 930 hours. I’d be sending those in for bearing replacement.
 
I called Emagair today and left voicemail but did not get a call back. I've downloaded the repair request form and will be sending both of them in for the flat fee checkup.

I don't know if the bearings were replaced previously at 550 hours. I'm going to guess they were not.

I haven't had any ignition related issues, but this is why we do annual inspections to catch problems before they happen!
 
I called Emagair today and left voicemail but did not get a call back. I've downloaded the repair request form and will be sending both of them in for the flat fee checkup.

I don't know if the bearings were replaced previously at 550 hours. I'm going to guess they were not.

I haven't had any ignition related issues, but this is why we do annual inspections to catch problems before they happen!

Just so you are not surprised like I was - the Emag website still discusses the $135 flat fee check up. When I sent my pMags in fairly recently to have this done, I was billed $295 each.

I would also highly recommend anyone running two pMags to install a monitor like theEI Commander. I have had numerous "challenges" with my pMags and the EIC has been invaluable providing data to work through this (which I am still working through).
 
The EMAG website also claimed that PMAG’s were less maintenance intensive than magnetos…but I didn’t have to pull my mags off every 100 hours.

That said, the PMAG’s have provided great service, although I’ll be honest; I don’t think I’m in tune enough with my aircrafts performance to recognize the performance increase over mags (except maybe reduced fuel burn).
 
SNIP
That said, the PMAG’s have provided great service, although I’ll be honest; I don’t think I’m in tune enough with my aircrafts performance to recognize the performance increase over mags (except maybe reduced fuel burn).
Reduce fuel burn is the gain with pMags. That and easier starts, better plugs, dirt simple timing and such.

Carl
 
Reduce fuel burn is the gain with pMags. That and easier starts, better plugs, dirt simple timing and such.

Carl
I would argue that automotive plugs with adapters are not 'better', just cheaper.
Fuel burn only improves because you are able to run further LOP if that's your thing.
If you pay someone to take of your plane mntc cost will be higher.
Generally accepted that you'll have higher CHT's with pmags.
Easier starts, that's debatable.
Hand propping, nope not happening.
Problem away from home, single source for repair.
 
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I would argue that automotive plugs with adapters are not definately not 'better', just cheaper.
Fuel burn only improves because you are able to run further LOP if that's your thing.
If you pay someone to take of your plane mntc cost will be higher.
Generally accepted that you'll have higher CHT's with pmags.
Easier starts, that's debatable.
Hand propping, nope not happening.
Problem away from home, single source for repair.

Can an argument be made that a wider gap creates a bigger spark, therefor better fuel burn. With Auto plugs generally we have a wider gap.

Hand propping my plane is not happening regardless of PMAG or any other ignition system, unless you are one of those Marvel characters in the movies.
 
I would argue that automotive plugs with adapters are not definately not 'better', just cheaper.
Fuel burn only improves because you are able to run further LOP if that's your thing.
If you pay someone to take of your plane mntc cost will be higher.
Generally accepted that you'll have higher CHT's with pmags.
Easier starts, that's debatable.
Hand propping, nope not happening.
Problem away from home, single source for repair.

Walt, quite a blast. Some thoughts:
- Better plugs as in a wider gap. Better plugs as the higher spark reduced fouling. If I never have to clean an aviation plug again it will be too soon.
- Fuel burn in cruise is reduced (same engine power) as the timing advances to more optimal firing angle - just like your car. ROP or LOP. Take off power timing is fixed, just like a mag.
- Get more power out of the engine at the same cruise fuel flow and CHTs go up. Physics. My CHTs in cruise (IO-360-M1B) are 350-370 - in the summer.
- I start in a blade. How many spam cans do you hear grinding away on the ramp waiting for the pitiful MAG spark to light the fires?
- If you really need to hand prop (starter died) you can (I don't recommend it). Considering the pMag retards timing for start I suspect hand propping would be more successful with pMags. Don't know and I will never try it. If your battery is flat, you should just charge the battery. If you are in Alaska on a gravel bar with a flat battery, I suggest poor planning.
- Single source repair? Like most everything on our planes these days? I can report that pMag after the sale service is top notch - not like a some vendors.

Carl
 
Teach me your ways Carl. I can get it to happen occasionally with my Pmag but getting the correct prime proves elusive most of the time.
Carl is not alone, I often get it started in one blade as well when cold engine. About 2 seconds of the boost pump is the right amount to get it started that way.Over priming usually causes more cranking for me.
 
EZ, Quick start for me too. Cold or hot.
I had a Pmag ignition coil go bad 4 years ago. I now carry a spare. $175. Have not needed to use it, of course.
Have enough plugs for 3-4,000 hours.
2 sets of adapters.
Pulling em at 100 hours, piece of cake.
 
I am not to keen to try hand propping an O-390.
A C-65 perhaps.
Thread drift; I hand propped an IO-520 on a Baron 58 once. Just once. Was the easiest hand prop I’ve ever done, and I suspect that was all luck. I certainly wouldn’t want to try it again.
 
Don't get me wrong, I think Brad and the others at EMAG do a great job and provide excellent service, a model company in that regard.
I just think some of the touted advantages as compared to mags are somewhat exaggerated, lately I've sent back a number of units for bearing changes which ends up costing around a kilo buck (for 2 units) with service cost and labor for customers. I've also had to spend quite a bit of time correcting/repairing bad wiring/installations at the less-than-ideal connector they use.
Are the advantages worth it, for some folks perhaps it is, for me, not so much.
 
Carl is not alone, I often get it started in one blade as well when cold engine. About 2 seconds of the boost pump is the right amount to get it started that way.Over priming usually causes more cranking for me.

I talked to Carl on the phone and have a subtle change I’m going to try. I think I am getting too much fuel often times. Sorry for the thread drift guys.
 
Away from home I had one 6-cylinder PMAG internal alternator fail at 45 hours. Unit still provided excellent ignition for start, and flight. Had I developed a dead electrical system then that one PMAG would have died. I have two...so the redundancy was acceptable for the flight home. Emag promptly repaired the unit at no charge.

RV-10 builders take note. If you have your aircraft battery(s) in the rear as the plans call for, and you pull your bus power from the battery side of the starter contactor at the firewall, as the Van's generic electrical system describes, you may have starting problems with the PMAGs.

This is rooted in the voltage drop seem at the starter contactor as the starter is pushing the engine thru each compression stroke. Turns out that the voltage drop at the upper stage of each cylinder compression (right before the PMAG fires during start) is just enough to affect the PMAG and it may not send a spark at TC. After much frustration and trying to figure out why my engine would not start I was informed of this RV-10 issue by Brad.

The solution was to run a new #6 wire from the battery contactor at the rear battery to the buses up front so as to avoid the voltage drop developing on the #2 wire at the starter contactor. This seems to have solved the problem.

Furthermore, Brad advised on building in the ability to "boot strap" an independent electrical power capability to the PMAG(s) in the event of a weak main battery. If you you have a weak battery you may get the engine to turn over...but that weak battery almost assuredly will be at a voltage during start that will prevent the PMAG(s) from firing.

My solution was to buy a cheap 8 AA cell battery pack with plug from Amazon. I keep it in one of the seat backs. Should I have a weak main battery I simply plug my AA cell pack into a receptacle behind the instrument panel. This receptacle is wired directly to the PMAG power (bypassing the normal power switch). Works like a champ. Using this setup with a weak battery, if the starter can get one of the cylinders to TC, my PMAG will throw a spark.

David
 
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David,

A weak battery is a weak battery. This is the root problem. Your running additional wires may mitigate but does not address this problem.

I can report that my dual PC-625 battery install in my old RV-10 never had this problem. The new RV-10 will be done the same.

Carl
 
Don't get me wrong, I think Brad and the others at EMAG do a great job and provide excellent service, a model company in that regard.
I just think some of the touted advantages as compared to mags are somewhat exaggerated, lately I've sent back a number of units for bearing changes which ends up costing around a kilo buck (for 2 units) with service cost and labor for customers. I've also had to spend quite a bit of time correcting/repairing bad wiring/installations at the less-than-ideal connector they use.
Are the advantages worth it, for some folks perhaps it is, for me, not so much.

I am a believer in the fuel efficiency benefits of EI, with proper advance, in cruise. But just do not get the fascination with Pmags. 100 hour inspections, $500 bearing replacements, automatic timing changes, sub-par connectors, no warranty if over a certain unobtainable temperature, etc. My EI has magnets on the flywheel with 0 maintenance and electronics on the cold side of the firewall. A $200 inspection or a $500 bearing swap easily covers the cost of a $30 backup battery with biannual replacement, mitigating the benefits of the built in alternator. And the battery still works at 700 RPM.

Just one guy's opinion.

Larry
 
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Away from home I had one 6-cylinder PMAG internal alternator fail at 45 hours. Unit still provided excellent ignition for start, and flight. Had I developed a dead electrical system then that one PMAG would have died. I have two...so the redundancy was acceptable for the flight home. Emag promptly repaired the unit at no charge.

RV-10 builders take note. If you have your aircraft battery(s) in the rear as the plans call for, and you pull your bus power from the battery side of the starter contactor at the firewall, as the Van's generic electrical system describes, you may have starting problems with the PMAGs.

This is rooted in the voltage drop seem at the starter contactor as the starter is pushing the engine thru each compression stroke. Turns out that the voltage drop at the upper stage of each cylinder compression (right before the PMAG fires during start) is just enough to affect the PMAG and it may not send a spark at TC. After much frustration and trying to figure out why my engine would not start I was informed of this RV-10 issue by Brad.

The solution was to run a new #6 wire from the battery contactor at the rear battery to the buses up front so as to avoid the voltage drop developing on the #2 wire at the starter contactor. This seems to have solved the problem.

Furthermore, Brad advised on building in the ability to "boot strap" an independent electrical power capability to the PMAG(s) in the event of a weak main battery. If you you have a weak battery you may get the engine to turn over...but that weak battery almost assuredly will be at a voltage during start that will prevent the PMAG(s) from firing.

My solution was to buy a cheap 8 AA cell battery pack with plug from Amazon. I keep it in one of the seat backs. Should I have a weak main battery I simply plug my AA cell pack into a receptacle behind the instrument panel. This receptacle is wired directly to the PMAG power (bypassing the normal power switch). Works like a champ. Using this setup with a weak battery, if the starter can get one of the cylinders to TC, my PMAG will throw a spark.

David

Sorry, but that is just poor design engineering. In the auto world all engine electronics work down to 8.5-9 volts in order to deal with starter draw on a weak battery. I remember SDS posting that there units don't drop out until 9 volts as well.

Larry
 
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Sorry, but that is just poor design engineering. In the auto world all engine electronics work down to 8.5-9 volts in order to deal with starter draw on a weak battery. I remember SDS posting that there units don't drop out until 9 volts as well.

Larry
With that in mind, one could say, in an aircraft any ignition that can not be self-sustaining for power is a poor design engineering.

Self sustaining and super easy of installation has been one of my primary attraction to PMAG. In three airplane that I have owned and installed PMAG, none failed or needed service by PMAG.
 
Sorry, but that is just poor design engineering. In the auto world all engine electronics work down to 8.5-9 volts in order to deal with starter draw on a weak battery. I remember SDS posting that there units don't drop out until 9 volts as well.

Larry

Just so the record is clear, you can power a P-Mag with a 9 volt battery and get a good start….I’ve done it just to see if what Brad says works - and it does.
 
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