Tom Baker Posted June 12, 2016 Report Share Posted June 12, 2016 Would you take that chance, Tom. When it is charging you will be close to 14v but with the engine off it could be considerably lower. I suspect Garmin says 14-28v instead of 12-28v for a reason. They could sell more if it was rated at 12v. That is just like any other small GA airplane with a 14v system. Like I said I have a customer with one in a SLSA, and it happens to be Rotax powered. I haven't heard any issues reported with it. Link to comment Share on other sites More sharing options...
gbigs Posted June 12, 2016 Report Share Posted June 12, 2016 There are a handful of non CT owners on this site, but to say most who post do not own a CT is a stretch. That is unless you are trying to use a different definition for "most" than a normal person would. Read it again, slowly, with a dictionary nearby... Link to comment Share on other sites More sharing options...
Anticept Posted June 13, 2016 Report Share Posted June 13, 2016 "14" volts is the name of the system, it doesn't actually mean it must be exactly "14" volts. Same with "28" volts, which often is around 25-26 volts at the input. These use switched mode power supplies. You could likely go as low as 8.5v before it goes blank. Link to comment Share on other sites More sharing options...
Doug G. Posted June 13, 2016 Report Share Posted June 13, 2016 "14" volts is the name of the system, it doesn't actually mean it must be exactly "14" volts. Same with "28" volts, which often is around 25-26 volts at the input. These use switched mode power supplies. You could likely go as low as 8.5v before it goes blank. Why would they recommend 14-28v and not 12-28v? I am aware that it is not exact, but I would rather have 12v with a fudge factor than 14v with a fudge factor, wouldn't you? Link to comment Share on other sites More sharing options...
Anticept Posted June 13, 2016 Report Share Posted June 13, 2016 Why would they recommend 14-28v and not 12-28v? I am aware that it is not exact, but I would rather have 12v with a fudge factor than 14v with a fudge factor, wouldn't you?It's goofy how it works. Like how it's 120/240 vs 110/220 on mains. CTs have a "14v" system, which charges to 13.2-13.5 volts. Anyways, I went and opened a 530w install manual. It lists 11-33v on some part numbers. Others are "single voltage" and only list one voltage. Even still, it will probably continue to function below 11 volts, but now we're eating into that "safety factor". Dynon lists 10-30v, but I know it can go as low as 8v. On that note, if your airplane is at all like mine, every time you go to start, the EMS powers off. That's because when starting, so much power is drawn, that the voltage drop become significant across any small amount of resistance, and the voltage inside the unit is too low for it to function. I have yet to see one that is actually damaged by this process. Anyways, for electronics, it's safer to go below the voltage than above it. Lower means that eventually, voltage drop will drop the system voltage too low to overcome the threshold voltage of some semiconductors (especially those used in switched mode power supplies) and the unit will cease to function. Going overvoltage, however, generates more heat on the semiconductor die and risks breaking down the insulation in capacitors (BAD), or some conductors and coils if they are crappy. Link to comment Share on other sites More sharing options...
Tom Baker Posted June 13, 2016 Report Share Posted June 13, 2016 Read it again, slowly, with a dictionary nearby... I read and understand fine. I even speak in terms other aviators can understand. I have been around this forum for quite some time. I know there are some non owners who post, but they are out numbered by those who own a CT. Link to comment Share on other sites More sharing options...
Doug G. Posted June 13, 2016 Report Share Posted June 13, 2016 OK, but the reality of a.c. is that the voltage has been increased slowly over the years. As you probably know transmission is more efficient at higher voltages. That analogy doesn't work here. I know that higher voltage can mean higher heat but low voltage can be an issue also, especially in relation to power supply and display, right? (I don't have your credentials, but I do have an extra class ham radio license. I have built a lot of equipment over the years.) Link to comment Share on other sites More sharing options...
Anticept Posted June 13, 2016 Report Share Posted June 13, 2016 OK, but the reality of a.c. is that the voltage has been increased slowly over the years. As you probably know transmission is more efficient at higher voltages. That analogy doesn't work here. I know that higher voltage can mean higher heat but low voltage can be an issue also, especially in relation to power supply and display, right? (I don't have your credentials, but I do have an extra class ham radio license. I have built a lot of equipment over the years.) There is a misunderstanding that I need to clear up. If we have a device designed for a specific voltage, and you push a voltage higher than what the device is rated, you will generate more heat than it's designed to take. I stated that in response to the "12v Fudge factor" bit. I made the assumption that it was failure of the device was what you were worried about. Thus, in a round about way, my response was meant to alleviate that concern by making this statement: going below design voltage isn't going to cause reasonably designed electronics to suddenly crap the bed. However, it appears to me that you already know that, so I am curious as to what that fudge factor is supposed to mean. And you are very much correct: generally speaking, higher voltages are more efficient from an energy efficiency standpoint; that is until the size of the insulation and isolation becomes a significant factor in the form and shape, which turns out, happens pretty darn quick in semiconductors. Imagine how big a particular processor design would have to be if it used 25 volts instead of 2.5 volts! The traces alone would generate a huge amount of heat! A side note: electric motors, however, react very badly to undervoltage. Generally, 10% variance is all motors can stand. Anyways, just because I hold certificates doesn't mean I'm qualified . I'd like to think so, but if you've done ham radio, you're going to be more skilled than I regarding electronics. Link to comment Share on other sites More sharing options...
Doug G. Posted June 13, 2016 Report Share Posted June 13, 2016 I agree with you. The side question had more to do with the difference between A.C. and D.C. power (a la Westinghouse/Tesla vs. Edison ????). My real question is why Garmin says 14v. I don't know the answer to that. I do know that I see about 12v regularly when I go to shut down. I would not want to regularly run a unit outside of specs, would you? Link to comment Share on other sites More sharing options...
Anticept Posted June 13, 2016 Report Share Posted June 13, 2016 I agree with you. The side question had more to do with the difference between A.C. and D.C. power (a la Westinghouse/Tesla vs. Edison ). My real question is why Garmin says 14v. I don't know the answer to that. I do know that I see about 12v regularly when I go to shut down. I would not want to regularly run a unit outside of specs, would you? As said before though, "14v" is the name of the system. It's not actually the spec. Also, let me pose it to you this way then: would you put a "12v" device on a 14v circuit? Anyways, it's name only. It will work fine in a flight design. Link to comment Share on other sites More sharing options...
Doug G. Posted June 13, 2016 Report Share Posted June 13, 2016 Now you lost me. How is it the name of the system when Garmin lists it under Specs? https://buy.garmin.com/en-US/US/in-the-air/discontinued/gns-530/prod119.html Link to comment Share on other sites More sharing options...
Anticept Posted June 13, 2016 Report Share Posted June 13, 2016 Now you lost me. How is it the name of the system when Garmin lists it under Specs? https://buy.garmin.com/en-US/US/in-the-air/discontinued/gns-530/prod119.html Because the marketing department, not the engineering department, writes that. The installation manual lists the voltage range as "11-33v". EDIT: actually, 10-33v. 11-33 is for another connector. Page 1-5: http://www.mstewart.net/Downloads/530W_IM.pdf Link to comment Share on other sites More sharing options...
Doug G. Posted June 14, 2016 Report Share Posted June 14, 2016 That makes it official. It will work with 12v. The marketing department is hurting their marketing! Thanks for the discussion. Link to comment Share on other sites More sharing options...
Anticept Posted June 14, 2016 Report Share Posted June 14, 2016 You can't buy garmin units or parts anymore anyways, they can only be obtained or serviced via a garmin dealer. Not even for experimentals. I know because i tried. Link to comment Share on other sites More sharing options...
Anticept Posted June 14, 2016 Report Share Posted June 14, 2016 You can't buy garmin units or parts anymore anyways, they can only be obtained or serviced via a garmin dealer. Not even for experimentals. I know because i tried. Link to comment Share on other sites More sharing options...
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