---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Sat 03/16/19: 4 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 07:06 AM - Re: Starters (Robert L. Nuckolls, III) 2. 07:11 AM - Re: Re: Three Questions on Z-07 (Robert L. Nuckolls, III) 3. 08:22 AM - Re: Re: Three Questions on Z-07 (Ken Ryan) 4. 11:21 AM - Re: Three Questions on Z-07 (user9253) ________________________________ Message 1 _____________________________________ Time: 07:06:58 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Starters At 02:15 PM 3/15/2019, you wrote: >That is a very common battery, any battery store will test it for you. > >On Fri, Mar 15, 2019, 13:31 Steve Kelly ><amsk22@gmail.com> wrote: >Bob,=C2 Thank you for the reply.=C2 I will try to >get out to the hanger early next week and check >the voltage readings.=C2 The battery is a PC680 >at three months old.=C2 =C2 Do you have a method >you would suggest to do a load/capacity check on it. That's a pretty fresh battery . . . this suggests the problem is elsewhere. However, in answer to your testing questions, I'll suggest that every owner of an aircraft should also own something like this https://tinyurl.com/yag4529y This LOAD tester allows you to load the battery to an output of 9 volts while waiting for the 15 second timer light to go out. Note the current at the end of 15 seconds . . . it should be in excess of 200A for small engines, 300A for larger engines. This test confirms the battery's avbility to grunt the extra-ordinary demands for cranking the engine. A CAPACITY test seeks to quantify the battery's ENERGY content . . . which is entirely separate from the capability to grunt a cranking load. There are some rather small batteries that have demonstrated the ability to crank a turbine engine https://tinyurl.com/yye6znqp But this product wouldn't run the aircraft's critical systems for very long after the alternator quits. There are dozens of 'tiny' products that offer a similar utility https://tinyurl.com/y2hzkq9l The way to cap check your battery is to set up your panel to operate your Plan-B (alternator out) electrical loads and monitor battery voltage with a voltmeter. The time it takes to reduce battery voltage to 10V (the lower limit for your avionics to operate). For example, a NEW PC680 has the following ENERGY delivery capability. Emacs! Assume a 4A endurance load. The curves say you're good to 3 hours. Here you have to tailor the question to match your own endurance requirements. If one hour meets your own Plan-B design goals, then according to the chart, the new battery is good for about 10A. Actually, you would want to rate the battery for about 8A given that maintenance protocols suggest replacing the battery at 75% of new capacity. Then there's the real-life test . . . turn on the goodies, start the clock, watch the voltage, measure the time then recharge the battery. If that time is equal to or greater than your design goals, then you're good to fly. How old is your starter? It MIGHT be that brushes and/or commutator are worn to the point of producing degraded performance. Bob . . . ________________________________ Message 2 _____________________________________ Time: 07:11:37 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Re: Three Questions on Z-07 At 01:52 PM 3/15/2019, you wrote: > >I would leave that drawing available unless there is some unknown failure >mode. There are different strokes for different folks. Someone will have a >perceived need that Z-07 will fill. "Perception" is the key term here . . . where I have to ask, what are the failure modes being addressed and what are the numbers that support the selection of hardware. A finely tuned Z07 might call for a 24 a.h. engine battery and a 10 a.h. device for avionics. But to what end? BOTH batteries are expected and maintained to meet the same design endurance. What then is the value for having two batteries versus one battery with the same energy content? I don't recall the discussions now that prompted the Z07 explorations . . . but I don't see that it makes sense now. Bob . . . ________________________________ Message 3 _____________________________________ Time: 08:22:26 AM PST US From: Ken Ryan Subject: Re: AeroElectric-List: Re: Three Questions on Z-07 The best reason I can think of to have two batteries is to get the engine started if the primary battery doesn't get the job done, and you happen to be on some remote Alaskan gravel bar. Many modern aircraft cannot be hand propped. On Sat, Mar 16, 2019 at 6:15 AM Robert L. Nuckolls, III < nuckolls.bob@aeroelectric.com> wrote: > At 01:52 PM 3/15/2019, you wrote: > > > I would leave that drawing available unless there is some unknown failure > mode. There are different strokes for different folks. Someone will have > a > perceived need that Z-07 will fill. > > > "Perception" is the key term here . . . where > I have to ask, what are the failure modes being > addressed and what are the numbers that support > the selection of hardware. > > A finely tuned Z07 might call for a 24 a.h. > engine battery and a 10 a.h. device for > avionics. But to what end? BOTH batteries > are expected and maintained to meet the same > design endurance. What then is the value for > having two batteries versus one battery > with the same energy content? > > I don't recall the discussions now that > prompted the Z07 explorations . . . but > I don't see that it makes sense now. > > > Bob . . . > ________________________________ Message 4 _____________________________________ Time: 11:21:54 AM PST US Subject: AeroElectric-List: Re: Three Questions on Z-07 From: "user9253" Sudden battery failure is rare, but it has happened . . . to me. My PC680 cranked the engine just fine. Then later, when I reduced throttle to land, the EFIS rebooted. The EFIS did not have an internal backup battery at the time, but now does. I sent the battery to Bob N. and he found a broken internal weld. I still only have one battery not counting the backup batteries inside of avionics. Each builder will wire their airplane the way that they want to. All we can do is educate them so that they can make informed decisions. A friend installed an avionics switch in his panel. I told him that the need for that switch is based on an old wives tale that has been handed down from instructor to student. And I told him that switch makes his airplane less safe. But I was only one person. Several others told my friend to install that switch. So he did. Some builders are willing to sacrifice money and performance for their peace of mind. All we can do is look over their shoulder and point out anything that is dangerous. If a builder wants to install two large batteries, he will do it whether there is a Z figure for it or not. Without guidance, his architecture could have a design flaw -------- Joe Gores Read this topic online here: http://forums.matronics.com/viewtopic.php?p=488105#488105 ------------------------------------------------------------------------------------- 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.