Dynon screens restart at engine start - why?

[Battson]

Just wondering why the screens restart sometimes when I start the engine.

Is this to do with voltage drop, or spike?

One screen has an internal battery power source, and it doesn't tend to restart as often as the one without internal power, but it will still restart some of the time.

Thanks for the explaination in advance!

 

[dynonsupport]

A screen with a battery should not restart when you start your engine. This may indicate your battery is non-functional. Does the unit run for 30 seconds after each flight when you turn off the master?

For a unit without a battery, the D120 shuts off at about 6V. This happens in some airplanes during engine start. If you have a small battery, it's cold, you have a permanent magnet starter, or small wires in your plane you can end up with this issue on some or all of your starts, but again the backup battery should solve this.

There is no designed in reboot from a high voltage spike, and we can tolerate up to 60V.

 

[Battson]

Ok that is interesting.

The backup battery is working just fine. Sounds like we should have 2 backup batteries!

The one with the backup battery was switched on via a complex process, as we were doing a lot of starts. Some times via the avionics bus power, other times via it's battery then master bus power added later, other times kept isolated etc. It restarted about 2-3 times in 12 starts.

The screen without the internal battery restarted every time we cranked the engine, but that's because the battery isn't well matched to the engine (and will be replaced), the instantaneous voltage drop during the in-rush current must be enough to trip it, before the battery recovered a fraction of a second later. It clicked off then instantly started to come back on-line, every time.