---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Wed 01/21/15: 3 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 05:13 AM - Re: Alternator/regulator (Gary Burdett) 2. 05:59 AM - Re: Power Generation without Battery? (Robert L. Nuckolls, III) 3. 12:01 PM - Re: Power Generation without Battery? (ChrisM) ________________________________ Message 1 _____________________________________ Time: 05:13:36 AM PST US Subject: Re: AeroElectric-List: Alternator/regulator From: Gary Burdett Bob, Thanks for the clarification . I think I jumped to confusion. Sent from my iPad > On Jan 20, 2015, at 8:08 AM, Robert L. Nuckolls, III wrote: > > > At 15:34 2015-01-19, you wrote: >> >> I have a JD/yanmar PM alternator and regulator with crowbar circuit. Voltage was starting to run over 15 volts at cruise rpms. Replaced battery and regulator, now hits 15.5 volts at anything over 2400 rpms on first test with a fully charged battery..???? > > > Regulator is not properly adjusted for maintaining > a lead-acid battery. Unfortunately, most of the > off-the-shelf regulators for pm alternators do not > offer user adjustments. > > Finding a drop-in replacement with friendlier > performance is about your only option. Your > problem is not uncommon and the folks who design, > manufacture and market these products seem oblivious > to the disservice they impose on their customers. > > > Bob . . . > > > > ________________________________ Message 2 _____________________________________ Time: 05:59:02 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Power Generation without Battery? At 16:49 2015-01-19, you wrote: Bob, I am building a Carbon Cub - a lightweight experimental design for backcountry use. It will use a fully electrically dependent Lycoming engine. I plan on 1 battery/2 alternators, and I desire the system to run the engine with any 1 of those 3 failed. Under what scenario do you perceive that a battery becomes unavailable to you? I want to use a lithium battery for starting purposes only. I am not worried about battery only endurance with 2 other power sources. Okay . . . Alternator technology is mature, but Li batteries seem to be still evolving. Some type of battery fault would seem be a likely failure mode in my planned system. (I'd like to monitor battery temp using a probe and my on board electronics, and to have some way to electrically isolate or even physically remove the battery). I plan to use your Z12 or Z13 architecture. Which #2 alternator are you considering? People I speak with advise me that alternators (even the SD8) are dependent on a functioning battery in the system, and that they will cease to function if the battery fails or is taken offline. Not true. Once they are up and running, all alternators will continue to run self-excited unless 'stalled' by a LARGE load, like 200W landing light or an electro- hydraulic pump motor. The SD-8 can be installed to self-excite (See Z figures). Many alternators on Lycoming engines will self excite due to their high operating speeds with the popular pulley ratios. Recent revelations regarding the Challenger/Aerovoltz scenario aside, there seem to still be legitimate issues with the current Li crop. At the very least they remain relatively unproven. It's not one 'crop' but a garden . . . albeit infested with some weeds. The type certificated lithium products like True Blue have 'full up' battery management systems that are quite capable of preventing events like that which plagued the Challenger owner. Further, had the Challenger owner availed himself of the knowledge and experience freely offered from the pages of this List and DOZENS of other sources, he would have caught the mis behaving rectifier-regulator before it became antagonistic to his battery. I'm working on the 'frosting' article to a series I did in Kitplanes on lithium batteries. A major feature of the article points out the constellation of design and marketing approaches for lithium cranking batteries in particular and consumer off-the-shelf cells in general. It will also discuss the range of offerings for 'battery management systems' which can range from a simple fuse built into one end of a cell . . . up to a bucket full of electronics and software that costs nearly as much as the battery itself! So I am concerned about the Li battery being a single point of failure capable of stopping the engine. Engine stoppage due to failed battery? Not if you take the time to understand how all those bits and pieces fit together to solve your particular puzzle. If you want to go lithium, go EarthX (Full up BMS). There are some up-n-comers nipping at EarthX's heels . . . How can I design around this problem? Simple . . . not necessarily easy but simple. Hang out here. Read. Ask questions (which are already under way . . . good for you!). When you hear/read/observe some bit of information from other sources, bring them here to the List for sharing/sifting of the simple-ideas in physics that define REAL performance and risks. Share your thoughts about load analysis, qualify your "plan-b" to deal with failures. Your misgivings are real but I suggest they are borne more of ignorance than of physical limits to performance of products that are thoughtfully and skillfully crafted. It's your ability to recognize those skills that will carry you forward with confidence. By the way, your 'advisors' who speak of alternator/battery relationships might enjoy joining us here too . . . their advise is dated and/or inaccurate. Bob . . . ________________________________ Message 3 _____________________________________ Time: 12:01:38 PM PST US Subject: AeroElectric-List: Re: Power Generation without Battery? From: "ChrisM" Bob, I think the most likely battery failure modes would be temperature related due mild overcharging/cell imbalance/high ambient temperatures. I think I'll be pretty protected from a runaway thermal overload due to frank over voltage as I will use your Z figures with overload protection/notification. An internal short may also be more likely with lithium than with lead acid. Regarding alternator #2: I request your advice. Running the engine with the EFII requires 10 amps - mostly for electric fuel pump. I think I need perhaps 15 amps for a comfort margin and to run the radio. Output curve vs rpm is significant considering fuel and ignition function are at stake. But this is a vfr aircraft and I can navigate and fly with nothing but the engine running. So the SD8 does not have adequate output. Perhaps adapting one of B&C's larger units intended for Continentals? Wind my own? Hopefully something off the shelf though! I contacted B&C on the self/persistent excitation issue and was advised that the SD8 requires a battery in the system to operate the regulator. He referred me to you. Also called Plane Power as it seemed their internally regulated design should be able to continue to run following removal of external battery power, but was advised not. Answers may have been tainted by my emphasis about actually keep the engine running! I don't think I have any large loads in the plane which would tend to stun the self-excited alternator. Think I may make a small placard to remind about being gentle with manipulations if running under such circumstances. I believe you drew Z12 and Z13 prior to predominance of 100% electrically dependent engines. They both show a magneto in the system for example. Do you feel these Z figures are appropriate for adapting to electrically dependent engines using a lead acid battery? Do you think Z12/13 are reasonable for use with a current technology (eg EarthX) Li battery? Which Z do you favor and why? If yes, is there some means to enhance the alternators propensity to continue to produce power following battery failure? What do you recommend for a first and second alternator for my system? Minimum output needed is 15 amps at perhaps 1800 engine rpm. Weight is a factor for my setup. Thank you very much for helping me understand how all these bits and pieces do fit together. Your willingness to offer your expertise and experience answering questions like these is very generous. Chris M -------- ChrisM Read this topic online here: http://forums.matronics.com/viewtopic.php?p=437421#437421 ------------------------------------------------------------------------------------- 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.