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05-07-2008, 12:28 PM
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Join Date: Jan 2006
Posts: 27
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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 ?
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05-07-2008, 07:37 PM
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Join Date: Jan 2005
Posts: 4,285
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Independence.
Quote:
Originally Posted by Fallalloveryou
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.
__________________
George
Raleigh, NC Area
RV-4, RV-7, ATP, CFII, MEI, 737/757/767
2020 Dues Paid
Last edited by gmcjetpilot : 05-07-2008 at 08:20 PM.
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05-07-2008, 07:56 PM
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Join Date: Feb 2005
Location: Chesterfield, Missouri
Posts: 4,514
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Quote:
Originally Posted by gmcjetpilot
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.
__________________
RV-12 Build Helper
RV-7A...Sold #70374
The RV-8...Sold #83261
I'm in, dues paid 2019 This place is worth it!
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05-07-2008, 08:23 PM
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Join Date: Jan 2005
Posts: 4,285
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Quote:
Originally Posted by David-aviator
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.
__________________
George
Raleigh, NC Area
RV-4, RV-7, ATP, CFII, MEI, 737/757/767
2020 Dues Paid
Last edited by gmcjetpilot : 05-07-2008 at 08:29 PM.
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05-09-2008, 10:30 PM
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Join Date: Oct 2006
Location: Gilbertville, Iowa
Posts: 8
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Special considerations
Quote:
Originally Posted by David-aviator
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...PS_Diagram.htm
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05-27-2008, 07:15 PM
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Join Date: May 2005
Location: Houston, Texas
Posts: 39
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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!!!
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06-05-2008, 07:08 PM
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Join Date: Dec 2007
Location: Flagstaff, AZ
Posts: 2,653
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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?
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06-05-2008, 08:05 PM
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Join Date: Dec 2006
Location: Arroyo Grande, CA
Posts: 938
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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.
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06-05-2008, 08:53 PM
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Join Date: Oct 2006
Location: torrance, ca
Posts: 650
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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
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06-06-2008, 06:06 PM
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Join Date: Dec 2007
Location: Flagstaff, AZ
Posts: 2,653
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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.
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