Sport EX question

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bcone1381
Posts: 2
Joined: Sat Dec 02, 2017 1:28 pm

Sport EX question

Post by bcone1381 »

I am beginning to design my electrical system, and will be following up with my instrument panel design as my project gets closer to completion.

1) How is the Sport EX display intensity dimmed at night.
2) If I use GRT backup battery, how is it wired? Is it used to power the display with the Engine is being started? When does it "kick into action?" If I have an alternator failure, I expect my main battery to provide voltage to the bus that supplies power to the EFIS. I really am desiring the GRT back up battery to power the display during engine start, and provide redundancy to the EFIS in the event the aircraft battery is inop.
Bobturner
Posts: 444
Joined: Mon Mar 11, 2013 6:34 pm

Re: Sport EX question

Post by Bobturner »

I have an HX but I think the answers are the same.
1. You can dim the display from the front panel controls, or you can wire a control voltage from an external potentiometer into an anolog input.
2. There are multiple power inputs. Wire main power to one, back up to another. Display will pull power from the highest voltage source.
GRT_Jeff
Posts: 802
Joined: Tue Dec 11, 2012 12:11 am

Re: Sport EX question

Post by GRT_Jeff »

A clarification on the failed alternator condition. The GRT battery is effectively a battery with charging circuit and diode that is always on and always trying to charge. It does not switch. You can connect power through it or connect it as an additional power source to devices that have multiple power inputs, like the EX. The EX treats both power inputs equally through simple diode isolation and this naturally takes the most power from the highest voltage. The EX does not do any switching. If the alternator fails and that power input has the same or lower voltage than the power input with the backup battery then the backup battery will be drained. You would need to turn off the battery output yourself with the switch on the output in order to save it for later. You need a switch anyway because the battery output is always on and that's the only way to disconnect the load from the battery. If you choose instead to wire only a single power input only through the battery, then you have the same problem, but no way to disconnect the backup battery and keep using the main battery in such a condition.
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