Flightdek 180 reporting lower voltage than battery

[jamespearce]

The power input line to the 180 is measured at 12.62 volts but the Dynon is reporting 11.8 volts.
Without the engine running, with all the avionics switched on and whilst testing my new radio installation, pressing the PTT causes the 180 to display a low voltage warning and flash erratically sometimes even switching off and back on. The Dynon seems to behaving like it can't run on the voltage it thinks it's being supplied with rather than the actual voltage. Any ideas? Thanks, James.

 

[Dynon]

This sounds like the voltage that is actually getting to the D180 is actually dropping below 10V (actually well-below, because the D180 can outperform its spec'd voltage). One solution to that is the backup battery, which will supply power when the starter pulls the aircraft battery that low. But, the amount of voltage difference you're reporting is a lot. Where are you measuring your voltage? Voltage drop across wires is expected, but what you're seeing (which is indicative of too much resistance somewhere) might be caused by a bad ground, or a loose power/ground connection, or possibly corrosion somewhere, again in the power or grounding going to the D180.

 

[jamespearce]

Thanks for the rapid reply. I am measuring at the battery but I will recheck at the Dynons power pin tomorrow and report back. I will also check the integrity of the units power / ground connections. Cheers, James.

 

[dynonsupport]

Also, on the D180, are you reading the voltage on the EMS or on the PFD? These come in on different pins. The one the system actually runs off of is on the PFD as part of the "M,E,I" list of voltages.

 

[jamespearce]

Good advice. I firstly changed the power+ takeoff from a relay to a connection directly from a + bus with an 18 awg wire as opposed to the 22 awg and then upgraded the ground to an 18 awg to a separate ground lug. It works a treat now but I am surprised by the drain the radio transmission takes when the PTT is operated, you can see the voltage being reported by the Dynon runs down very quickly. This was clearly the problem and the wiring upgrade has sorted it out. Thanks for your help, James.