Roger Lee Posted August 14, 2012 Report Share Posted August 14, 2012 Discussion On Dynon website. This may help some understand what you are seeing on your Dynon D120. Cut and pasted. Aug 12th, 2012 at 7:46pm OfflineNew Member Posts: 8 My Dynon 120 indicates voltage at full throttle of 13.3-13.4 volts. A DVM reading at the cigaret ligher shows 13.8=13.9 volts. How do I change the Dynon to read the correct voltage? Back to top IP Logged Reply #1 - Yesterday at 9:05am Dynon Support Offline Forum Administrator Dynon Employee Dynon Technical Support Posts: 8719 The D120 isn't wrong. The voltage at the D120 connector isn't the same voltage as what is at your cigarette lighter. Because every wire has resistance, voltage drops occur all over an airplane. You can't calibrate this out because it changes over load. The best thing you can do is run the D120 directly off the battery without sharing it's power wire with any other devices. Also, if you use Bob Nuckol's system with a standby bus powered by a diode, your essential stuff is a diode drop lower (~0.4 to 0.7V lower). Overall, absolute voltage is not as important as changes. If you know 13.4 is where the plane flies with everything working fine, then suddenly having 14V or 12V in flight is when you worry. Amps is sensed by a small voltage that is generated by an amps shunt, is a big hunk of metal that is designed to generate a 1 mV of voltage differential between two wires for each amp that passes through it. Blog: http://blog.dynonavionics.com Docs: http://docs.dynonavionics.com News: http://newsletter.dynonavionics.com Phone: 425-402-0433 (7am-5pm Pacific weekdays)Back to top Amps is sensed by a small voltage that is generated by an amps shunt, is a big hunk of metal that is designed to generate a 1 mV of voltage differential between two wires for each amp that passes through it. Link to comment Share on other sites More sharing options...
Jim Meade Posted August 14, 2012 Report Share Posted August 14, 2012 I posted that message. Is the D120 connected directly to the battery or is it through some connections where there is a voltage drop? I'm not sure I fully accept the explanation that I'm going to get a 0.5v drop through a short chunk of wire. My impression is the electrical system is sufficiently loaded that I like to have a pretty precise idea of what is going on. I'm trying to get a bunch of information gathered so that when I redo my panel this winter I incorporate as many changes as are appropriate. If I need to rerun some wires, I'll do it. Actually, I'm as interested in amps as I am in volts, but one question at a time. Link to comment Share on other sites More sharing options...
Roger Lee Posted August 14, 2012 Author Report Share Posted August 14, 2012 I know you posted it, but I never post names from a cut and paste. It seemed like an appropriate post here because several of these guys have ask in the past. It is not connected directly to the battery, but can be. Link to comment Share on other sites More sharing options...
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