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Mike Buettgenbach

Active Member
Question for those flying . . . I've conducted about 5 engine runs so far (carb balance and all). Noticed that the EFIS blanks during the start. While it recovers quickly, I would rather it not do that. Batt is fully charged.

Is this blanking common?

I flew w/ Mike Seager a couple wks back, as I remember, the 'company' airplane didn't do this.
Thx
 
This is very common if you don't have a backup/Aux battery that is isolated from the main bus. The main bus voltage drops quite low during cranking, and most EFIS's will drop off line unless you have something to kep the volts up.

Paul
 
Paul is right. If your Dynon EFIS has the built-in battery backup it should not be blanking on you during startup. Enable the voltage display on the EFIS and it will display the backup batt voltage. May just be that you need to let the backup battery charge (which it will do during a few runs).

You didn't mention which Dynon EFIS you have. If you have a standalone Dynon EMS (like I do), it will generally blank on you during startup unless you have made other provisions (such as an external backup battery). It recovers so quickly though there's no problem.
 
Ditto to everyone else...

My Dynon D100 EFIS and Dynon D10A EMS both cycle off and then back on during engine start. It takes about 5 seconds for the EMS to boot back up. Since it takes oil pressure about 5 seconds to become an issue if it doesn't come up to adequate pressure, that's the first item I look at as soon as the EMS comes on-line.

No big deal. Still love the EFIS / EMS combo from Dynon!
 
Voltage drop

By no means am I any kind of electrical engineer, but I was always taught that having a computer (or your radios/transponder/GS) drop off-line during start, or the possibility of spiking it during start, is sufficiently high enough to warrant only bringing everything online after you've got your engine running, hence the old "avionics master" switch we see everywhere.

Does anyone know Dynon's take on having their systems online during startup vs the risk of killing one?
 
Dynon recommends leaving their unit ON

KRviator said:
Does anyone know Dynon's take on having their systems online during startup vs the risk of killing one?
Click to expand...

Dynon recommends leaving their unit ON while starting the engine.

If it really bothers you (the blanking), a backup battery (internal or external) would be a fix. The Dynon reboots so quickly, that for me it is a non-issue.
 
Old wives tale

the possibility of spiking it during start, is sufficiently high enough to warrant only bringing everything online after you've got your engine running
Click to expand...
According to my mentor, Bob Nuckolls, an author and electrical guru, an electrical spike from the starter is an old wives tale proven false by extensive testing with an oscilloscope. Some avionics manufactures even believe that old rumor. Dynon knows that engine starting does not harm their avionics and even recommends that the D-180 be turned on before engine start. The biggest problem of operating avionics during engine start is not a voltage spike, but rather a voltage sag. Since the D-180 has a backup battery, voltage sag is not a problem for it.
While an avionics master switch makes it convenient to shut off all of the avionics, it is a single point of failure. When it fails, all of the avionics will be lost. Likewise for the Com Stack fuse. Even the stall warning will be lost. When Van's redesigns the Control Board, I would like to see a lager fuse block so that each unit can have its own fuse. Fuses are cheap and light weight.
Joe
 
Backup battery

Ok guys. I had the same problem, but when I took the backup out to check the voltage, it read "zero" on a volt meter. The battery, being a lithium ion type, will shut itself down to prevent damage if the voltage goes too low. Dynon repaired the D180 charging circuit? when I sent it back and now the Dynon does not blank on starting.
 
Another problem TODAY

When I was shutting down today, after 1.8 hour flight, the Dynon went blank. The "I" voltage is 16.1, so Dynon said that the backup battery seems to be charged. Told me to cycle it a few times, and if that doesn't work, to pull the unit, and disconnect the backup battery and everything for a while, then see if that will reset things. We'll see. ( 142 hours )

John Bender
 
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