Yup, I've used many for different applications over the years. They hold a charge a long time and go and go. That's why we're leaning towards this known quantity/ quality. I have a 7 amp hour one over 20 years old now, still pretty good despite some abuse over its life.
Van's Air Force
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SDS CDI vs Pmag
- Thread starter FLY6
- Start date
Yup, I've used many for different applications over the years. They hold a charge a long time and go and go. That's why we're leaning towards this known quantity/ quality. I have a 7 amp hour one over 20 years old now, still pretty good despite some abuse over its life.
czechsix
Well Known Member
Ross, I mentioned DO-160 in terms of a reference for ensuring aircraft electronics are adequately hardened for the intended operating environment...you can design the system with the objective to meet these industry standards (many of which have been developed by lessons learned the hard way) without actually spending the significant money & time to prove that the equipment passes all the tests. It's like designing an airframe to Part 23 structural standards but not spending $ millions to actually prove (aka certify) it. You can also selectively design for the conditions you care about and ignore the rest. I don't want to pay for a unit that is environmentally sealed against sand, dust, and hydraulic fluid when I'm going to put it in my panel, but it would be nice if a voltage surge doesn't leave me with an engine failure...
Also with respect to a built-in backup battery, I think it's a great idea but please make it optional, easy to replace, and some kind of built-in monitoring/self test method would also be great. One problem with backups is you don't tend to use them until you really need it, and that's a bad time to discover that it died last year without notifying you...
As I said, we'll do as much testing as we can afford, to approach the applicable DO 160 standards and protecting the unit/ maintaining power to the unit under all conditions is paramount for sure. The battery backup will be optional since some will already have a larger backup battery system installed.
It will certainly have a monitoring system built into the unit. We already have some ideas on that part. To avoid any conflicts, it's not going to be tied into ship's power for charging. The goal would be to charge externally every 90 days or so which seems practical with the PS AGMs batteries.
Ross,
1. Will the new CPI2 have the capability to monitor battery (batteries) health?
2. Will there be an audio alert that could be fed to an intercom or audio panel?
Right now, looks like the backup battery will be an option for those who want it. It will assess backup battery health on bootup so you can make a go/ no go decision before you even start. Probably have an LED on the face to warn you of low voltage as well.
Might be able to add an output for an audio alert. Maybe at the 9V level as you'll have already got an alert prior to startup. Ideas and feedback on this aspect welcome here.
I'm researching electrical systems for use with a dual SDS EI for my RV-8 equipped with an IO-360. I am considering something similar to a two battery system like the one depicted above (DanH) from a different but related thread, specifically, "Dual Lightspeed igntion install - warning" http://www.vansairforce.com/community/newreply.php?do=newreply&p=1174921
Some EFIS are limited to allowing the real time monitoring of the electrical system (battery) health to one channel, mine is. Should I decide to go with a dual battery, one alternator system, like the one shown above, I would need to check Batt2 health before each flight.
If the CPI2 allowed the monitor or check of voltage for for at least one, possibly two batteries this would help. An audio and visual alert would be excellent.
The strategy we're looking at right now would be to self check the CPI2 backup battery on power up display voltage of it and maybe an LED for go/no go, then switch to the main source if it's above 12V or so. We may change or refine that as we get into further thinking and testing.
As usual, I'm late to the show. My CPI will be superseded before it even gets installed. Haha.
I like the green.
In the electronics world, things can evolve and change quickly as new features and products emerge. We hinted on a 2018 release of this about a year ago. We're letting people know now about the new CPI, months before planned release, even though we know it may cost a lot of 1st gen CPI sales, because we think it's the right thing to do.
Nobody wants to just finish buying some new avionics only to find that 2 weeks later the manufacturer brings out something newer and better.
Tomcat RV4
Well Known Member
The color SURE don't effect the great service or quality ! Tom
Ross, I must apologize. I certainly didn't mean anything negative towards SDS. I recognize how quickly the electronics world evolves and I was just laughing at how this always happens to me. I'm sure GRT will release a new EFIS/EIS in a few months...right after I purchase a system
I look forward to learning about the CPI2 and maybe I'll install it rather than buying a second CPI module (I'm installing a single module dual coil system as a stepping stone into the EI world).
I look forward to learning about the CPI2 and maybe I'll install it rather than buying a second CPI module (I'm installing a single module dual coil system as a stepping stone into the EI world).
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Ross, I must apologize. I certainly didn't mean anything negative towards SDS. I recognize how quickly the electronics world evolves and I was just laughing at how this always happens to me. I'm sure GRT will release a new EFIS/EIS in a few months...right after I purchase a system
I look forward to learning about the CPI2 and maybe I'll install it rather than buying a second CPI module (I'm installing a single module dual going system as a stepping stone into the EI world).
No worries, I didn't take any offence to your comment, it's happened to all of us. One other guy asked why we'd announce this so early and possibly hurt current CPI sales. We like to involve our customers in the design process as we end up with a better product appealing to a wider market in the end. As on the EM-5, many of the best new features on it were suggested by existing clients using earlier versions.
Ross,
Will the new CPI2 have the LOP Switch located on the CPI2 device or will it (LOP Switch) need to be panel mounted?
Will the CPI2 have a provision for 1 power source or 2?
Thank you,
Will the new CPI2 have the LOP Switch located on the CPI2 device or will it (LOP Switch) need to be panel mounted?
Will the CPI2 have a provision for 1 power source or 2?
Thank you,
We're trying to move away from external switches on the new design, have to see how that goes.
We were discussing power backup in depth this afternoon during a brainstorm session.
1: Optional backup power for one CPI and its coil pack
2: Optional backup power for two CPI and both coil packs
Do both CPIs and coil packs share a single backup battery or have separate ones?
Do we allow charging the backup battery from the main bus or keep totally isolated?
We want to have useful capability and function without excessive complexity and cost. This usually means design simplicity.
We were discussing power backup in depth this afternoon during a brainstorm session.
1: Optional backup power for one CPI and its coil pack
2: Optional backup power for two CPI and both coil packs
Do both CPIs and coil packs share a single backup battery or have separate ones?
Do we allow charging the backup battery from the main bus or keep totally isolated?
We want to have useful capability and function without excessive complexity and cost. This usually means design simplicity.
In the IT space, usually simplicity for the customer means complexity for the developer.
My suggestion (taken from data center computers):
- Each coil has dual power inputs, one is primary the other is backup. If primary does not work, it auto fails over to the backup.
- Each cpi has dual power inputs, one is primary the other is backup. If primary does not work, it auto fails over to the backup.
- Via the CPI/Ignition cable, the CPI is notified of power failures. CPI can then pass up the chain.
- Each CPI is cross connected to the opposite coil. If a coil does not have standby power coming from the primary CPI, it auto switches to the second CPI.
- In terms of charging, I like solutions like this one: https://www.bluesea.com/products/7601/m-Series__Automatic_Charging_Relay_-_12_24V_DC_65A
Allows you so have multiple batteries charge off a single bus.
Is that over engineered enough? Really simple for the customer, painful for you.
The customer can then chose to have serial separate systems, or just by adding a cable provide point system redundancy at either the CPI and/ot the coil.
Tim
As I look at the SDS "Dual CPI Wiring" diagram, Revision 1.0, dated January 17/17, I see a few things that you might consider for removal from the aircraft panel and integrate into the new CPI2 architecture, specifically:
1. LOP Switch
2. Coil Pack 1 Switch
3. Coil Pack 2 Switch
Q1: Do both CPIs and coil packs share a single backup battery or have separate ones?
A1: Maybe it could be designed and built in such a way that this could be a user decision and configured accordingly and easily with a jumper. The options could be: a.) No backup battery. b.) One back up battery for one CPI/coil pack. c.) One back up battery for both CPI/coil pack. d.) Two back up batteries. One for each CPI/Coil pack.
Q2: Do we allow charging the backup battery from the main bus or keep totally isolated?
A2: Consider making it consistent with how EFIS MFG are doing it. Or, this could be a user decision and configured accordingly.
I have two Slick mags that are approaching rebuild time. I started out wanting electronic ignition for the obvious benefits it provides. Early on, I leaned towards Pmags because they are very easy to install. They do, however, have their limitations. I will not go into it here.
I want the ability to change my timing, not just my curve, for specific RPM and MP. I prefer the ease in which the SDS CPI allows the operator to do that. By integrating some of the components on the "Dual CPI Wiring" diagram into your proposed new device, you add complexity on your side but subtract it on my side. You might also be able to design in even more reliability by removing potential points of failure currently depicted on the user side of the wiring diagram.
It's a priority to try to remove the external LOP switch for sure.
There's currently an internal function to do a "mag check". We'll carry that over to the new design.
There may be instances where people want to shut off coil power. If we internalize that, people would not easily have that option. These are all things we need to weigh.
Our intention is to provide a vendor designed option for emergency backup power (complete with battery, relays and mounting tray)to those who want it. People who already have or want to design their own setup could skip our solution and use their own.
We don't mind taking longer to design the CPI2 to be less complex for the user but we generally don't believe in design complexity and adding more points of failure for perceived risks which are minute in real-life. Components which are not there, can't fail.
Our products are made to order for each customer. This includes coil mounting, options and wiring harnesses. When it comes to activating options, some are done with jumpers, others in software. We make this stuff easy to change for ourselves or customers.
We have to remember that this keeps the engine running or not, arguably more critical than glass displays. If battery charging isolation gives us less chance of taking down the ignition, we'd go that way. If we can find a super reliable way to charge the backup battery (BB) and still have super reliability against all considered faults, we'd go that way.
When it comes to wiring engine electronics, at some point, excellent power and ground connections have to be made to the aircraft. That's something nobody can control except the installer and in our experience, those are the #1 causes by far of the electronics going down.
99% of the stuff sent back to us which "does not work" either does work just fine (indicating a user wiring issue) or got very wet.
Keep the input coming. We'll try to consider and implement all the good ideas.
There's currently an internal function to do a "mag check". We'll carry that over to the new design.
There may be instances where people want to shut off coil power. If we internalize that, people would not easily have that option. These are all things we need to weigh.
Our intention is to provide a vendor designed option for emergency backup power (complete with battery, relays and mounting tray)to those who want it. People who already have or want to design their own setup could skip our solution and use their own.
We don't mind taking longer to design the CPI2 to be less complex for the user but we generally don't believe in design complexity and adding more points of failure for perceived risks which are minute in real-life. Components which are not there, can't fail.
Our products are made to order for each customer. This includes coil mounting, options and wiring harnesses. When it comes to activating options, some are done with jumpers, others in software. We make this stuff easy to change for ourselves or customers.
We have to remember that this keeps the engine running or not, arguably more critical than glass displays. If battery charging isolation gives us less chance of taking down the ignition, we'd go that way. If we can find a super reliable way to charge the backup battery (BB) and still have super reliability against all considered faults, we'd go that way.
When it comes to wiring engine electronics, at some point, excellent power and ground connections have to be made to the aircraft. That's something nobody can control except the installer and in our experience, those are the #1 causes by far of the electronics going down.
99% of the stuff sent back to us which "does not work" either does work just fine (indicating a user wiring issue) or got very wet.
Keep the input coming. We'll try to consider and implement all the good ideas.
flyboykelly
Well Known Member
7 and 9 cylinder!?!?
Our systems are all waste spark so hard to do on odd numbers of cylinders plus only a tiny market for Experimental radials so there would be a very long return on investment to develop new hardware and software.
I would go for the 70-80 minutes and 2.1 pounds.
qtrmiledan
Well Known Member
Back time
Second vote for 2.1 lbs and longer time.
Second vote for 2.1 lbs and longer time.
I choose the second option. 70-80 minutes and 2.1 pounds. What battery chemistry? SLA, LIPO, other?
Lead acid AGM.
Alternate power charging
Ross,
A quick browse on EBay I see solar power controllers that support AGM, and many various sizes, and specs for MC (Mono Crystaline) flexabile solar panels. I'm not an expert with this technology but interested if this might be a light weight alternative for keeping an AGM battery fresh. The MC panels look like they could be incorporated into sun visors, or integrated some way fairly easy.
Ross,
A quick browse on EBay I see solar power controllers that support AGM, and many various sizes, and specs for MC (Mono Crystaline) flexabile solar panels. I'm not an expert with this technology but interested if this might be a light weight alternative for keeping an AGM battery fresh. The MC panels look like they could be incorporated into sun visors, or integrated some way fairly easy.
Right now we are looking to recharge the backup battery via ship's power with an isolation circuit for low and over voltage. Seems few people are keen to worry about that staying charged by external means even though these batteries retain over 90% charge after 2 months at 20C ambient. All options are on the table at this time though. Appreciate the input from all here.
Carl Froehlich
Well Known Member
One approach is to look at aircraft power requirements as a system, not as individually components. This way you can find more efficient and effective ways to achieve design objectives instead of the brute force approach of having multiple backup batteries; one or two for the igntions, one for the left EFIS, one for their right EFIS, etc.
Carl
I really appreciate the dialog and the way you interact with those interested in your products. I've learned much this way just by following the conversation. In a word, impressive. Thank you.
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Toobuilder
Well Known Member
Yep, color me a +1 for that trade.
We only care about keeping the engine running if the rest of the aircraft power systems go down for whatever reason, keeping things as light/ simple and reliable as possible. The design goal is to get you over an airport and safely on the ground to sort something like this out. We've seen, after being in this game over 20 years, that many people prefer (or should have) a vendor solution/ option in this regard.
battery capacity
I'd vote for the 70-80 minutes!
Also, I've been researching EI aux battery options, and one thing I've noticed is that these small batteries don't have nearly their nominal AHR's at 1.5amps (rough EI amp draw). Per the manufacturers data, a Powersonic PS-1220 (2.5AH & 2.1lbs) will only do about 1.5 AHR's at 1.5 amps....approx. 60min of backup. And that's assuming a new battery charged/maintained at 100% capacity.
I'd vote for the 70-80 minutes!
Also, I've been researching EI aux battery options, and one thing I've noticed is that these small batteries don't have nearly their nominal AHR's at 1.5amps (rough EI amp draw). Per the manufacturers data, a Powersonic PS-1220 (2.5AH & 2.1lbs) will only do about 1.5 AHR's at 1.5 amps....approx. 60min of backup. And that's assuming a new battery charged/maintained at 100% capacity.
We're down around 1.1 amps at 2500 rpm with a 4 cylinder setup. We look at the rating to 9V.
With respect to the new CPI2, will there still be independent power inputs for each ECU and each coil?
Said another way. Will your CPI2 dual EI offering have independent ECU or will they be integrated somewhat like the SDS EM-5 offering?
Said another way. Will your CPI2 dual EI offering have independent ECU or will they be integrated somewhat like the SDS EM-5 offering?
Larry DeCamp
Well Known Member
Amp Hours definition ?
I am following this thread closely because I am installing Ross's duel CPI soon. Talking with Kathy (earthx) at Osh, there is a significant difference in voltage available on the amps/time curve. Lead acid goes full charge to zero volts in a straight line. LiIron goes to a minimum voltage able to sustain ignition over the rated period. Maybe Kathy could jump in here and discuss this significant point.
I am following this thread closely because I am installing Ross's duel CPI soon. Talking with Kathy (earthx) at Osh, there is a significant difference in voltage available on the amps/time curve. Lead acid goes full charge to zero volts in a straight line. LiIron goes to a minimum voltage able to sustain ignition over the rated period. Maybe Kathy could jump in here and discuss this significant point.
So far the plan is to run the CPI and its coil pack off ship's power. Optional will be a backup battery pack that we offer with the mounting bracket and wiring to sustain power for a period of time if the rest of the aircraft electrical system takes a dump somehow.
You can have a CPI unit with one or two completely independent circuit boards inside to drive either 1 or 2 coil packs. One integral head will be able to access either board something like the current dual EM-5 setup.
I looked for suitable LiFePO4 batteries in this AH range and there's not much to choose from which are economical to purchase. Similar 2.5 AH ones are about 10 times the price but they are about half the weight of course. I wouldn't consider any other alternate lithium battery chemistry as they just introduce more risk in the cockpit potentially. Also, it seems these batteries are not so good at -20C where some of our Alaskan customers operate. Lead acid AGM just seems like the best overall compromise.
We consider the time to 9V as the significant factor to effectively fire the coils.
I will pick up 3 PowerSonic AGMs tomorrow and we'll bench test them running the coil pack and CPI. See how they do.
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Ross,
What would be slick since the coil is powered off the controller, is have a plug into the controller for the backup battery.
Let the controller handle all power switching, drawing extra power to charge the battery when needed.
Also, I would be in the 70-80 minute camp.
Tim
What would be slick since the coil is powered off the controller, is have a plug into the controller for the backup battery.
Let the controller handle all power switching, drawing extra power to charge the battery when needed.
Also, I would be in the 70-80 minute camp.
Tim
No, the coils are not powered from the controller only triggered from it, they have separate power, switching and fusing. This backup battery will power both devices.
Switching power sources will be automatic via the controller.
Ok, that is what I though originally but I must have misread a recent post.
Cheers and good luck
Tim
Have you established a price schedule for the new SDS CPI and it's options?
We're aiming to keep the CPI pricing without the backup option the same as now- $1170US. This will be the price regardless of coil mounts chosen. We want to be priced below P Mag which is the big dog in this market at the present time.
There will probably be some other new features added which I can't disclose at this time.
Can't say what the backup option will cost yet but I believe we should be able to keep it below $100. This would include the battery, CNC'd tray, hardware, wiring etc. The control circuitry will be in all CPI boxes so the option can always be added later too.
There will probably be some other new features added which I can't disclose at this time.
Can't say what the backup option will cost yet but I believe we should be able to keep it below $100. This would include the battery, CNC'd tray, hardware, wiring etc. The control circuitry will be in all CPI boxes so the option can always be added later too.
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Bill Boyd
Well Known Member
Inquiring minds ask newbie Q's ;-)
It just occurred to me that the wasted spark concept that's so easy to grasp with a 4 cylinder 4-stroke engine is a bit of a head-scratcher with 6 cylinders firing at 120-degree intervals. Seems like the wasted spark(s) would occur about 120* before exhaust stroke TDC and again at 120* into the intake stroke (less whatever advance is being run at the moment).
What keeps the charge from lighting off during the intake stroke? Google search was no help to me
I know you guys have long ago figured this out, but I'm just curious how the need for a distributor is avoided in this application.
It just occurred to me that the wasted spark concept that's so easy to grasp with a 4 cylinder 4-stroke engine is a bit of a head-scratcher with 6 cylinders firing at 120-degree intervals. Seems like the wasted spark(s) would occur about 120* before exhaust stroke TDC and again at 120* into the intake stroke (less whatever advance is being run at the moment).
What keeps the charge from lighting off during the intake stroke? Google search was no help to me
I know you guys have long ago figured this out, but I'm just curious how the need for a distributor is avoided in this application.
It's still a flat motor with opposing cylinders firing 360 apart.
Firing order is 1-4-5-2-3-6, so 2 fires 360 after 1, 3 fires 360 after 4, and 6 fires 360 after 5.
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Bill Boyd
Well Known Member
but I assume there's 120 degrees difference among the firing times of 1 & 4 & 2 & 5, etc.
Still trying to wrap my mind around how that's done in a 6-cylinder 720-degree firing cycle engine without a distributor or without firing a wasted spark during the intake stroke. Or else the spark on the uncompressed ingoing mixture has no effect??
If I'm having a brain fart, just refer me to a Youtube vid and I'll go away.
Still trying to wrap my mind around how that's done in a 6-cylinder 720-degree firing cycle engine without a distributor or without firing a wasted spark during the intake stroke. Or else the spark on the uncompressed ingoing mixture has no effect??
If I'm having a brain fart, just refer me to a Youtube vid and I'll go away.
Toobuilder
Well Known Member
The 6 cyl coil is really a 3 pack of dual output coils. The wasted spark only occurs on one plug at a time, not all six. The coil driver is what tells individual coil pairs to fire - its a bit like an electronic distributor.
Bill Boyd
Well Known Member
