---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Sat 03/31/07: 5 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 05:38 AM - the battery dragon . . . (Robert L. Nuckolls, III) 2. 08:25 AM - OFF DIY engine monitor (Joe & Jan Connell) 3. 11:31 AM - "GAMI" Lean Check, Was: DIY engine monitor (BobsV35B@aol.com) 4. 04:19 PM - Re: Rear Mounted Batteries - more questions (RV_10) 5. 08:10 PM - OT: looking for ride (David M.) ________________________________ Message 1 _____________________________________ Time: 05:38:41 AM PST US From: "Robert L. Nuckolls, III" Subject: AeroElectric-List: the battery dragon . . . >Comments/Questions: I am building a Jabiru J430 and plan to include your >crowbar overvoltage system and low voltage detector. I am planning on a >dual battery where the second battery supports the main bus but not the >starter motor. The plan is to put a power diode between the bus and the >main battery. This means that that both batteries will charge from the >regulator but the second battery will not contribute to starting and >provide a sink to the bus to ensure voltage is maintained to the bus even >during starting. The idea is for the second battery to keep the electics >going in the event of main battery failure. Do you think this make sense? Unless you're planning not to maintain your battery, then 'battery failure' is exceedingly remote. The battery can be the most reliable source of power in the airplane. Since you've expressed a concern for keeping certain electro-whizzies operating under battery-only operations, (1) WHICH devices are the most useful, how much (2) CURRENT do they need and for (3) HOW LONG? After you've deduced these answers, what is your (4) PLAN for making sure that the battery in your airplane is up to the task? There are two qualifying tests of a battery. (5) LOAD testing proves the battery's ability to carry high loads such as starting the engine. This is the kind of test a service station operator puts on your car battery using a device similar to this one from Harbor Freight: http://www.aeroelectric.com/Pictures/Tools/HF91129_4.jpg Passing this test simply says the battery contains sufficient ENERGY delivered through a sufficiently LOW INTERNAL RESISTANCE to start the engine. The second test is a measure of (6) CAPACITY. This proves the battery's ability to perform under conditions (1), (2) and (3) above. It matters not how many batteries you install or how you wire them if you do not craft a preventative maintenance (a) PLAN to make sure your design goals for battery only endurance are met. The fact that you can get the engine started is but one of the two features that need monitoring. Further, unless you choose to meet an endurance load goal of a hand-full of minutes (like the FAA's favorite 30), then you'll need to establish some protocol for seeing that your goals are met throughout your ownership of the airplane. This will involve either (b) periodic replacement of what appears to be a perfectly good battery - cause it started the engine or (c) periodic CAPACITY TESTING against your personalized design goals defined by (1), (2) and (3) above. This can be easily accomplished with one battery but it does commit you to deciding which protocol offers the lowest cost of ownership. (b) throw a new $50 battery in every annual or (c) acquire the $tools$ and spend the $time$ to track your battery's condition such that design goals for battery only operations are consistently met. What you've proposed in your query does not make sense under the protocols established to operate your airplane at all times confident that the battery is going to be there to do the task you've established for it. The thing you need to do is establish PLAN (a) that will embrace the philosophy of (b) or (c) and then stick to it. If you do not have a copy of the 'Connection, I'll suggest you acquire or borrow one and review chapter 17 on system reliability. Join the AeroElectric-List and avail yourself of the knowledge, experience and understanding of dozens of folks who have slain the dragons you're concerned with. It doesn't need to be expensive or heavy. Bob . . . ________________________________ Message 2 _____________________________________ Time: 08:25:07 AM PST US From: "Joe & Jan Connell" Subject: OFF AeroElectric-List: DIY engine monitor Guys, Some of the postings on this topic have discussed the work done by GAMI in regards to lean of peak. I might be incorrect but the GAMI folks are usually working with fuel injection, not carburetors. Please correct me if I'm wrong... Joe Connell ________________________________ Message 3 _____________________________________ Time: 11:31:42 AM PST US From: BobsV35B@aol.com Subject: "GAMI" Lean Check, Was: AeroElectric-List: DIY engine monitor Good Afternoon Joe, You are correct as far as why GAMI got involved in this endeavor. It is also easiest to fix the balance if the engine is injected. However, the diagnostic capabilities of the lean check are just as important for a carbureted engine as they are for one that has fuel injection. The problem is that it is much more difficult to correct poor distribution on a carbureted engine. There are many things that can be done, but I do not believe it is within the realm of subjects appropriate to this list. Do Not Archive Happy Skies, Old Bob AKA Bob Siegfried Ancient Aviator Stearman N3977A Brookeridge Air Park LL22 Downers Grove, IL 60516 630 985-8503 In a message dated 3/31/2007 10:27:26 A.M. Central Daylight Time, jconnell@rconnect.com writes: Guys, Some of the postings on this topic have discussed the work done by GAMI in regards to lean of peak. I might be incorrect but the GAMI folks are usually working with fuel injection, not carburetors. Please correct me if I'm wrong... Joe Connell ************************************** See what's free at http://www.aol.com. ________________________________ Message 4 _____________________________________ Time: 04:19:05 PM PST US From: "RV_10" Subject: RE: AeroElectric-List: Rear Mounted Batteries - more questions Hello 'Lectric Bob, Thank you for all the fantastic effort you put into this group. It is extremely helpful to those of us with zero earlier experience in this area. I have read the Connection a couple of times and I have been pondering the whole issue of batteries and locations and fat wires etc. Attached is a schematic of a Z-14, architecture for rear batteries. This is not your current Z-14, and I don't know now where I got this from, but it very specifically states that the Aft Ground Buss is NOT Grounded to the airframe. My wife and I are building an RV-10. We are planning an all electric IFR panel and a two PC625 battery, two alternator electrical system. Would you please make your comments specific to this setup? Am I correct in assuming that there is an ideal setup for a two rear battery, two alternator system, which is the Z-14 attached, and then there is a more practical setup, which has the batteries grounded at the rear. Is this correct? Would you please comment on the relative merits of these two different approaches, and especially comment on any downside of both approaches? If you ground both rear batteries as suggested down the back to the airframe, do you then set up your avionics ground bus at the panel simply by connecting it to the firewall Ground? Are there any issues or concerns with doing this? >From a purely electrical perspective, would it be preferable in our situation (ignoring weight and balance questions for the moment) to have either battery situated up the front somewhere? If yes, which would be preferable to put up the front, and why? I also have a couple of other questions on the attached Figure Z-14. Does the single ground lead from both batteries to the front provide a single source of total failure? And lastly, why have you specified the copper/brass strap on the power side of the main battery in the attached Z-14? Thank you once again for all your very generous input. John Cleary -----Original Message----- From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Robert L. Nuckolls, III Sent: Thursday, 29 March 2007 12:28 AM Subject: Re: AeroElectric-List: Rear Mounted Batteries - more questions At 08:19 AM 3/28/2007 -0500, you wrote: > > >Bob, > >Now you are confusing me.. > >Yes, I did look at the link you provided. > >Using the generic aircraft - single battery schematic for schematic on >metal tube frame. >Battery (Odyssey 680) and contactor will be located under baggage >compartment floor behind seat backs. > >I thought we were supposed to run a ground wire from the battery to the >brass ground bus plate (with all the quick connect tabs on it) which was >to be mounted on the firewall. Isn't using the airframe for ground now >generating two paths for ground - hence possible problems? Local grounds in all metal airplanes can practically depart from "ideal" for the following: Batteries, strobe supplies, landing/taxi lights, pitot heaters, position lights, hydraulic pumps for landing gear (because they're intermittent) but not for air-conditioning compressors (because they're continuous). >I'm about ready to wire in my rear mounted battery (before covering). I >will use flexible wire for the battery terminal connections (and to the >local ground if that's what I am supposed to do). No problem attaching >ground leads to the frame if a good idea. It would eliminate an extra wire >to top and bottom strobes and tail position light... but I was already >resolved to run + and gnd to each (using a small local-next to battery >version of the brass ground bus with quick disconnects like in the front) > >I'd appreciate your input. It's never 'bad' to run all electro-whizzies to a single point ground but if one wishes to take advantage of the ground-friendly, all-metal airplane with the cited compromises, there's no risk of having an unhappy noise moment. It's most important to pay attention to grounding potential victims such as avionics and instrumentation. These should return to the firewall ground point per Z-15. I'll add some notes to Z-15 next revision to clarify this point. Bob . . . ________________________________ Message 5 _____________________________________ Time: 08:10:05 PM PST US From: "David M." Subject: AeroElectric-List: OT: looking for ride Will share fuel and flying for our leg, at least. My wife and I would like to get from the Houston, Texas area to Huntsville, Alabama (preferably to 3M5, Moontown Airport) around April 17 or so. We have a car here in Houston so we can drive a couple of hours to an airport, then we'll ride our bikes back to Houston. Thanks, David M. ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message aeroelectric-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/AeroElectric-List.htm Web Forum Interface To Lists http://forums.matronics.com Matronics List Wiki http://wiki.matronics.com Full Archive Search Engine http://www.matronics.com/search 7-Day List Browse http://www.matronics.com/browse/aeroelectric-list Browse Digests http://www.matronics.com/digest/aeroelectric-list Browse Other Lists http://www.matronics.com/browse Live Online Chat! http://www.matronics.com/chat Archive Downloading http://www.matronics.com/archives Photo Share http://www.matronics.com/photoshare Other Email Lists http://www.matronics.com/emaillists Contributions http://www.matronics.com/contribution ------------------------------------------------------------------------------------- These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.