---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Mon 09/30/13: 2 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 07:20 AM - Re: Charging the Aux Battery (Carlos Trigo) 2. 08:34 AM - Re: Charging the Aux Battery (Robert L. Nuckolls, III) ________________________________ Message 1 _____________________________________ Time: 07:20:38 AM PST US From: "Carlos Trigo" Subject: RE: AeroElectric-List: Charging the Aux Battery Thanks Bob So you confirm that on Dual battery, One main Alternator and an Aux alternator, with no cross-feed contactor, the Aux battery contactor must be closed during normal operations otherwise the Aux Battery will not be charged. Then, what's the advantage of having 2 batteries? Only to have more electron juice available? Carlos -----Mensagem original----- De: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] Em nome de Robert L. Nuckolls, III Enviada: 30 de setembro de 2013 01:51 Para: aeroelectric-list@matronics.com Assunto: Re: AeroElectric-List: Charging the Aux Battery --> At 01:46 PM 9/29/2013, you wrote: >--> > >Bob and all > >This is probably a dumb question but I will make it anyway. >In a Dual battery electric system architecture, like Z-14 for example, >the Aux Battery will not be charging in flight unless the aux batt. >Switch is flipped On (thus closing the Aux Batt contactor), right? > >Carlos Z-14 is dual battery/dual alternator, split-bus system. The aux battery is maintained by its dedicated alternator. In Z-14, normal ops are conducted with everything ON except the cross-feed contactor. On other dual battery systems with only one alternator and perhaps an aux alternator, then both battery contactors are closed during normal operations to be charged in parallel. Bob . . . ________________________________ Message 2 _____________________________________ Time: 08:34:00 AM PST US From: "Robert L. Nuckolls, III" Subject: RE: AeroElectric-List: Charging the Aux Battery At 09:22 AM 9/30/2013, you wrote: Thanks Bob So you confirm that on Dual battery, One main Alternator and an Aux alternator, with no cross-feed contactor, the Aux battery contactor must be closed during normal operations otherwise the Aux Battery will not be charged. Then, what's the advantage of having 2 batteries? Only to have more electron juice available? Essentially, yes . . . but capable of being partitioned into separate tasks should the alternator fail. During alternator outage, an Aux battery might be assigned the task of supporting an electrically dependent engine while the main battery would perhaps support an e-bus. This isn't just about storing 'more juice' . . . it's about selecting, crafting and operating an architecture that offers the most favorable failure modes effects analysis. FMEA is a simple exercised of looking at EVERY part of your electrical system and asking the questions that drive your decisions toward a more FAILURE TOLERANT design. I'll suggest you review these two pieces found on our website . . . http://tinyurl.com/kzfgtpt http://tinyurl.com/lpvth8d The answer to your question about dual batteries is broader than to explain their function. The question you need to answer first is "why would I think of having two batteries and how would they participate in a aerial dance contest where one or more of the contestants are throwing in the towel." This isn't about seeing the most reliable parts . . . it's about building the most reliable SYSTEM wherein absolute reliability of parts doesn't drive risk. It is much less expensive to design for failure tolerance than to buy only components with established reliability studies. My personal design goal for aircraft is to deprive any single failure of forcing me to break a sweat in the cockpit. Given a set of hardware limits and mission goals for the airplane, then the pieces need to be assembled in such a way as to minimize risk. Many of our brothers add 'backup batteries' as a salve for their apprehensions about lost of some really handy gadget on the panel . . . without consideration of the BIG PICTURE. My own apprehensions are best assuaged by the notion that even if my airplane's capabilities degrade to little better than a J-3, as long as the wings stay on, the engine keeps running and the flight controls are hooked up, I have a well understood opportunity to complete the flight comfortably. I've flown rented A-36 Bonanzas with LOTS of goodies on the panel without the slightest concern about the maintenance records for any particular appliance. This is because I fly with these things in my flight bag. http://tinyurl.com/d5mrjgh With fresh batteries installed before departure http://tinyurl.com/kjuhl67 Whether the salve for your apprehensions includes a second battery is a decision you need to answer by asking a LOT of other questions with simple answers that illustrate predictable consequences. Bob . . . ------------------------------------------------------------------------------------- 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.