Lightspeed Ignition Wiring

I am building a 9A and trying to wire the power to the dual Lightspeeds for my O-320. The manual says to connect the supplied power cable to a breaker and directly to the battery. The power cable is a shielded cable with the center conductor going to the positive side and the shield going to the negative side of the battery. My question is about the length of unprotected cable from the battery through the firewall to the breaker. After the breaker is protected. Before the breaker is not. How have others done this?

mdud

Don't worry its pretty easy

mdud said:

wire the power to the dual Lightspeeds. The manual says to connect the supplied power cable to a breaker and directly to the battery.

The power cable is a shielded cable with the center conductor going to the positive side and the shield going to the negative side of the battery. My question is about the length of unprotected cable from the battery through the firewall to the breaker. After the breaker is protected. Before the breaker is not. How have others done this? mdud

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The short answer is you don't have to leave the center conductor (POS) unshielded except for an inch at the very end. Don't worry.


This is how to do it. Peal back the insulation and shield only an inch and than splice in a wire to run the ground to where you need. This way you have max shield.

=====================---(+)
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Here is what it will look like.

http://www.aeroelectric.com/articles/pigtail/pigtail.html

You will solder and wire wrap a pigtail onto the shield for the ground. Of course heat shrink it all. This will minimize the center conductor from being unshielded, BUT it probably is worry for nothing. The ground does not need to be shielded of course. This is a good clean way to do it from a wiring / installation standpoint.

Also be sure to support and strain relief the POS wire. It will not do any good to have a fancy shield if the POS wire breaks off at the battery lug. Those two wires are as important as your wing spar and crankshaft to staying in the air. Of course you'll route two separate independant power lines in parallel. However having physical separation is key idea. I'd power one from the battery side of the master relay and one on the battery, again two physically separate positions. To run one power feed from the battery to power dual LS ignitions is a bad idea. Frankly, one FEED from the battery BUSS is OK, as long as ONE is direct to the battery. Make all connections as high quality as possible, stout, robust and protected. Done right you'll have a lifetime worry free installation.

Also consider a SMALL AUX BATTERY to drive one ignition as Klaus shows. I have plans for dual LS and will use a small Aux battery. It will add an independant power supply and isolation.


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It might help to know why your are doing this?

The reason for direct connection to the battery is its simple , bypasses the master relay and main buss. Also a direct battery feed to the LS is a safety thing. If you ever have an electrical fire, God forbid, you will turn the master off first thing. You don't want to turn the ignition off. Therefore the independent power feed direct to battery. The down side of the battery feed is you MUST turn the ignition's off along with the master after shut down.

BUT WHY SHEILD? Well it may be overkill but here are the usual reasons for a shielded wire. BTW power wires are not often shielded.



Why did Klaus spec the battery power wires to be shielded? Well you have to ask Klaus, but my opinion is the Light Speed power line MIGHT make RFI (radio freq interference) and cause noise in your radio or intercom (may be). The other reason for shield power cable is a shielded wire is more stout. You could run separate single wires for each, Pos power and negative and not have a "noise problem". The LIGHTSPEED will not care.



**RFI Noise - Radio transmission involves a form of non ionizing ElectroMagnetic Radiation (EMF). The radio spectrum is say from 100Khz to 1Ghz. Below is the sonic range and above its into the microwave, radar, infrared, visible light, UV, x-ray, gama & cosmic range. When ever some device sets up alternating current (freq) in the radio range, in a wire of proper length to resonate at that "wave length" (antenna), nearby wires also of the right length or proximity can also resonate and can pick up that RFI. Many ways to keep these accidental radio transmitters from transmitting and accidental radio receivers from receiving. One way to avoid receiving or RFI is shielding, to drain off that external EMF. Transmitting is different but the idea of EMF is the same, shielding works both ways. However weight & cost makes shielding impractical for all wires. Also not all wires or devices make or are affected by EMF.

George,

Great info, but I think the concern was about the lack of circuit protection. For what it's worth, I put an inline fuse on mine a couple of inches back from the battery connection.

Great Idea

szicree said:

George,

Great info, but I think the concern was about the lack of circuit protection. For what it's worth, I put an inline fuse on mine a couple of inches back from the battery connection.

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Oh yea great idea. I struggled with that.

I mean its a hard choice. Running a HOT battery wire a good distance to a CB with out a fuse could be ugly.

On the other hand may be a fusible link might be better? Something that will not FAST blow but on the other hand will not make the wire turn into 4 feet of a glowing RED smoking snake, burning anything nearby.

They do make nice inline fuses. If going fuse I'd size as big as possible for the wire not the load. For example a 18 awg wire will "fuse" at about 83 amps, so a 20 amp fuse would work, even a little more. It would be just for a hard short. A 30 or 40 amp fuse would work. If the wire shorts dead to the battery, it will go to +1000 amps in short order and fuse will blow within a fraction of a second (before the wire got red smoaking hot).

(As a kid I did that on an old Ford car, running an unprotected hot battery wire to a car stereo. Yep, I grounded it and it was spectacular. Fortinitly the wire melted before too much damage was done or burned the car down. Look at all new cars they have a power fuse box right there next to the battery. In the old days they used fusible links. So on second thought fuses should be fine.)

Why did Klaus spec the battery power wires to be shielded?

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It might be as simple as mechanical protection for the conductor.

szicree said:

George,

Great info, but I think the concern was about the lack of circuit protection. For what it's worth, I put an inline fuse on mine a couple of inches back from the battery connection.

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Steve,
What kind of inline fuse / holder did you use? Some are very unreliable.

Bussman

fl-mike said:

Steve,
What kind of inline fuse / holder did you use? Some are very unreliable.

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Mike I am not Steve nor did I play Steve on TV or stay at Holiday Inn. The BussMan brand makes very nice in-line fuse with that use a STC type blade fuse. They have Mini, Std and Maxi that goes up to almost like 50 amps. Just do the Google. The ones I am thinking have two short pig tails you splice in and the holder is heavy duty rubber/plastic with a cool cap attached. I am NOT talking about the big ANL fuse and fuse holders some people attach to their firewall, also made by Bussman (and others). You could go that way as well.

This is what I am talking about, take your pick.
http://www.bussmann.com/6/BladeFusesandAccessories.html

Fusible link data point

A fusible link has worked good so far for my single lightspeed ignition (flying 200 hrs and 2 1/2 years). It's located right at the hot side of the master relay. I emailed Bob Knuckles a few years ago on this issue and this was his advice. Fusible links are supposed to be very reliable.

Greg

Fusible Links

Grigson said:

A fusible link has worked good so far for my single lightspeed ignition (flying 200 hrs and 2 1/2 years). It's located right at the hot side of the master relay. I emailed Bob Knuckles a few years ago on this issue and this was his advice. Fusible links are supposed to be very reliable.

Greg

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Thanks for all the good suggestions. Many good points made and I will get some type of fusing for the power leads just for my peace of mind. With the ground shield protecting the inner conductor it may not be necessary but I can't see any problem with being extra careful. I am thinking that the fusable links are the most likely choice for me. Thanks again.

mdud

Fusible links

I like a fusible link but what is it. (For those that don't know.)


Fusible link is like a fuse but non-replaceable easily. You can buy them ready made and compact in auto stores. They are basically a sacrificial part of a wire the melts, one time. If it does melt down you need to splice in a new fusible link. These where common on cars in the 70's. You can tell by looking at wires off the battery, there is a thick barrel part an inch or two long. Now most cars use fuse boxes adjacent to the battery, no fusible links.

Bob has a home grown DIY fusible link, which is really a sacrificial length of smaller gage wire that will melt and burn if overloaded. To protect that RED HOT GLOW WIRE in the event of a short, you wrap it in fiberglass sleeve. Seems like a lot of effort when commercial fusible links are still around. Most car part stores have them.

In line fuse holder are very common now and the ATC blade fuse reliable. In the class tube says the fuse was may be a little more delicate. To recommend a fusible link is it doesn't rely on two contacts to hold the fuse in place.

The choice is yours. A fusible link application is a "OH NO", don't think it will ever fuse and don't want it to deal. Of course replacing a fusible link is harder but than again its something that should never fuse. Fusible links come in all shapes and sizes and types, but like a fuse its something made to melt and OPEN the circuit. Personally most fusible links have gone to what is really a fuse or slow blow fuse. My idea is just oversize the fuse greatly, 50%-75% more of the wires max capacity. (Max is well over its max continuous.)

Dual battery

I've seen klaus's dual battery diagram. He has ignition A connected to main battery and ignition B switchable to main or Aux. What would happen if you would take out the power select and the voltmeter have both ignitions connected to both batterys. This would simply it even more although the voltmeter would of been useful . Any thoughts ?

Independence.

Fallalloveryou said:

I've seen klaus's dual battery diagram. He has ignition A connected to main battery and ignition B switchable to main or Aux. What would happen if you would take out the power select and the voltmeter have both ignitions connected to both batteries. This would simply it even more although the voltmeter would of been useful . Any thoughts ?

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Klaus's diagram

Well I don't know if I follow you, but you could have two parallel batteries driving two ignitions in parallel. You can throw in some diodes as well. If you had dual batteries in parallel they need to be the same type, size and condition. I like your idea. Others have done it, but you lose some flexibility or ability to isolate. A B-sys volt meter is good for system info. There's 50 ways to wire dual batteries with dual E-ignition's. KISS is key.

With your idea however you lose something called isolation or Independence. You really don't want the batts tied together all the time. It is nice to have the two Bats separate driving two separate ignitions. With Klaus's design using a diode to tie the A/B sides together, A-Ign is driven by main Bat and B-Ign is driven by Aux and Main Bat. That is fine but both ignitions "see" the main Bat. What if the main Bat failed or alternator went wild. Unlikely but what if.....?


ACR - Auto Charge Relay / "BatteryLink"
It would be nice on that cross-tie device between the Main and AUX Bats, driving the EI's, which can open up manually or automatically to protect the AUX battery and B ignition.

For example the main Bat or alternator goes nuts, the cross tie opens and the Aux Bat drives the B-Ign, fat happy & dumb. Say the Aux battery has a melt down? Could it take the whole system down? Well Batts are pretty reliable.

To the rescue the boat electrical folks make such a device to tie two batteries together which will automatically parallel or isolate them. If volts go to high or low it will drop the tie to keep the other battery from being overcharged or drained. It's a nice device and its more than just a dual battery paralleling diode deal.

The Battery link is logic driven with a small IC micro computer with solid state switching. It monitors both batteries and switches the tie as needed. The down side is the electronics are hot all the time, so there's a small parasitic drain when parked. It's made by Blue Sea Marine Electrical Products, product is CL-Series BatteryLink™ ACR, PN 7600. There is a ton of info if you hunt around the link below. It is less than $100 and weighs 0.85 lbs. Is it needed? Probably not but it's a coold device.

http://bluesea.com/category/2/productline/overview/386



There is an issue of starting and voltage "brown out" affect on EI's. It's nice having one ignition on a AUX battery that's not being used for starting to keep the volts up on that ignition. Klaus system does that with the diode.

The key for dual LS's, a must, is dual batts. You want the physically separate wiring and as much as you can. Last think about independence/isolation A & B as much as you reasonably can. With single alternator you have to tie into that main system to charge the aux battery. How you wire them is up to you.

gmcjetpilot said:

Klaus's diagram

Well I don't know if I follow you, but you could have two parallel batteries driving two ignitions in parallel. You can throw in some diodes as well. If you had dual batteries in parallel they need to be the same type, size and condition.

However you lose something called isolation or Independence. It is nice to have the two Bats seperate. Even Klaus design has a diode tie. It would be nice on that cross tie to have a device to open up (manually or automatically) to protect the AUX battery and the #2 ignition (say of the the main bat or alternator goes nuts).

Adding a switch or meter in there adds more complication. I like your idea but than you lose some flexibility or ability to isolate as well as some system info. There's 50 ways to wire dual batteries and ignition, but KISS is key.

Also there is an issue of starting. It's nice having one ignition on a AUX battery that will not be used for starting to keep the volts up on that ignition.

The key is TWO batteries for dual LS's. How you wire them is up to you.

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Seems to me that the most KISS set up is one LS and one impulse coupled mag. There is no compelling reason to have 2 electronic ignition systems as one will run the engine just fine and the mag will always get you home.

I have 2 batteries and would prefer to have just one, the darn things weigh 14 pounds each. Plus they have to be in parallel with some sort of charging diode system so they can be charged off of the one alternator. The only reason 2 batteries are good, and George mentions it, is sometimes the starter will drag the voltage down so low the electronic ignition system will loose its brain and could fire way off of TDC.

I had it happen once (in my Lycoming days) and it broke the starter ring.

David-aviator said:

Seems to me that the most KISS set up is one LS and one impulse coupled mag. There is no compelling reason to have 2 electronic ignition systems as one will run the engine just fine and the mag will always get you home.

I have 2 batteries and would prefer to have just one, the darn things weigh 14 pounds each. Plus they have to be in parallel with some sort of charging diode system so they can be charged off of the one alternator. The only reason 2 batteries are good, and George mentions it, is sometimes the starter will drag the voltage down so low the electronic ignition system will loose its brain and could fire way off of TDC.

I had it happen once (in my Lycoming days) and it broke the starter ring.

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I agree 100% with that idea, but some folks (like me) want that extra 2%, so your point is well taken. Dual matching ignitions gives max gain, but mixing two different ignitions line a EI/Mag combo or even different types of EI's, doesn't give optimal power/economy. Frankly some folks that just putt-putt around local get less out of EI's, to the point where two Mags are fine. The OLD magneto is still a very awesome device for providing reliable spark. They are not perfect but one thing they have, independence from electrical power.

There is no solid state electronics or bull to go wrong with a mag. The only wire is a P-lead to tell it to shut off. If the P-lead fails open it runs anyway. I was watching the drag racing on TV and those top fuel drag cars have TWO BIG magnetos bolted to the side of the engine.

Special considerations

David-aviator said:

Seems to me that the most KISS set up is one LS and one impulse coupled mag. There is no compelling reason to have 2 electronic ignition systems as one will run the engine just fine and the mag will always get you home.

I have 2 batteries and would prefer to have just one, the darn things weigh 14 pounds each. Plus they have to be in parallel with some sort of charging diode system so they can be charged off of the one alternator. The only reason 2 batteries are good, and George mentions it, is sometimes the starter will drag the voltage down so low the electronic ignition system will loose its brain and could fire way off of TDC.

I had it happen once (in my Lycoming days) and it broke the starter ring.

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My particular situation is a little different than the one above. I have a O320-H2AD. It has one drive driving two mags. I either have two mags or no mags. I chose to go with no mags. Dual batteries don't have to match. My aux battery is a small 5 amp/hr sized to drive one ignition only. It does not get used on start and is only used in 'all other systems failed' mode when the pilot activates the power select switch. See link to diagram below.

I wonder if the power select switch is really necessary. What would be the harm in keeping the second ignition always on the aux batt? Normal operating would have power running through the schottky diode keeping the aux batt charged and powering the second ignition. In the event of a problem with the charging system and the main batt, the second ignition remains powered without pilot intervention keeping the big fan up front spinning. I have a feeling that things may get kind of busy if a pilot really needs the aux batt because of multiple failures (alternator and main batt) and would appreciate not having to switch more switches to keep the engine running. If the engine would stall, the aux batt would not have the power for restart. A hot ignition would not do much good after the engine stalls, say on departure.
http://www.lightspeedengineering.com/Manuals/PS_Diagram.htm

Mdud,

I have an 0-360 Lycoming with the dual mag type drive system as well, and I found the ideal setup was to run a single 1200 series Bendix impulse mag in place of the dual mag (it is a perfect fit and is a MUCH more powerful mag than any other out there on the market). I also installed a single crank trip LS electronic ignition system which is all the engine needs, and is far cheaper than a dual system. With this setup I not only have two independent ignition systems, but also two independent drive systems...it's the best of both worlds, and of course the mag requires NO functioning battery like your dual electronic systems will. I only need one battery in my system, so it is a very simple AND reliable setup!!!

Ok, I'm about to wire my system and I have a couple of questions. The first is mechanical: How the h do you get those input connectors through the firewall? I can't find grommets/shields big enough with a small enough center hole. While they did a beautiful job with the solder connector, I wish they'd used individual pins so you could feed it through a smaller hole and insert the pins into the connector body after, like my BMA autopilot cables. Oh, well, it is what it is. So how have others dealt with it?

Second, do I understand that the ignitions are hot while the batteries are connected? I have a P III, so I can use the key option; will that ensure they are not hot? Or should I plan to connect to the master solenoid instead of the battery so that they won't be hot while the master is off, at least?

Finally, I assume each ignition box requires it's own MP connection (the interconnect won't share the info). Is there a source for a T fitting for that tubing?

The reason for the shielded power lead is two-fold. First, the LSE EI has a fly-back converter to get the needed high-voltage for the sparkers; these have a tendency to feed back the high speed transients out onto the power lines which could raise havoc with RFI/EMI. Originally the switching frequency was chosen so as not to put harmonics on the Loran 100kHz. Secondly, all of the current to/from the battery and the unit is contained on the coupled shielded wire and so no common-mode currents exist which could couple into other low-level devices. Again, the desire is to contain any switching currents totally within the battery-unit wiring.

If you're talking about the hall-effect sensor cables thru the firewall, I cut mine and used crimp-style D-sub connectors. Just make sure you have the proper crimper if you go that route. Also, my sensor cables were too short (by at least a foot), so I had to extend them anyhow. I have no idea how Lightspeed came up with the cable lengths they supply. My sensor cables were too short and the RG-400 coax was wayyy more than needed.

Heinrich Gerhardt
RV-6, flying

Ok, I got a response from Klaus. He claims the connectors can go through a 1" opening if the shell is removed. I did that and it's 1/5" either way; maybe a bit smaller going sideways but not too much before the connections bend/break. I think I'll use ACSs 1.25" shields and 'keyhole' the opening to get the connector through. The excess shield should cover the keyhole slots and I'll go over it with RTV. I need to anyway, as the center opening at 3/8" is too large for the cable so RTV is called for there as well. Hi-temp RTV, of course.

I've got a line on a T fitting for the tubing; Klaus suggested McMaster-Carr. There are a couple of local distributors, so that's taken care of.

The 'hot' issue was my own brain-fade. You either have a switch for the ignition circuits or the P IIIs can use an optional line to the key switch, kinda like a mags P-lead connection to the key switch. Solenoid stays out of the loop, so I don't need one for my aux battery. I don't know why that was confusing me yesterday. All good now.

Emailed Klaus yesterday, why he wants the "ground" to "go around the houses" and not direct to the battery ground, which is just a couple of inches away from my Lightspeed control boxes.

His reply: "Das powerkabel kann 0,3volt ripple haben, deshalb sollte das abgeschirmt sein" (The powerkabel can have a 0,3 V ripple, that's why it should be shielded).

As you may know, Klaus is a German, who has lived in the USA for many years now. He can still speak German though. He told me that he lived not far away from where I live and, in his younger years, used to go to the Discos in our nabourhood. It's a small world, isn't it?

Pilottonny said:

Emailed Klaus yesterday, why he wants the "ground" to "go around the houses" and not direct to the battery ground, which is just a couple of inches away from my Lightspeed control boxes.

His reply: "Das powerkabel kann 0,3volt ripple haben, deshalb sollte das abgeschirmt sein" (The powerkabel can have a 0,3 V ripple, that's why it should be shielded).

As you may know, Klaus is a German, who has lived in the USA for many years now. He can still speak German though. He told me that he lived not far away from where I live and, in his younger years, used to go to the Discos in our nabourhood. It's a small world, isn't it?

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Ya, Klaus ist einer Weltgebiten Amerikaner! Loosely translated, Klaus is a Great American! Feel free to hammer me on my conjugations...