Heated AOA power usage

[rckol]

I am trying to size battery and bus power requirements.

The heated AOA installation manual indicates a 100 watt power usage at 13.8 volts, from which I calculate a current of 7.25 Amps.

Is this a short term surge value during start up or a possible steady state requirement?

If there is a significant difference between the two, can you please elaborate a bit on the power drawn in the startup and operating states?

TIA

 

[dynonsupport]

You should assume it draws 8 amps all the time.

The reason it's 100W is that is what is required to heat up the probe at 200+ knots when it's really cold out. All GA heated pitots are in this range. I believe the ones on jets are up in the 1000W range

Our probe is unique in that it only draws as much power as it needs to to heat up. So if you are going slow or it's warm out, it doesn't take as much power. But the whole purpose of a probe is to keep the ice off, so your system needs to be able to deliver 100W to it all the time.

 

[rckol]

Thnaks much.

Of course for wiring, fusing and primary alternator sizing I would use the 100 watts, but since my aircraft has a Vne of 165 knots and will not be in the flight levels, it would be useful to know what the probable current draw would be under less extreme conditions, to consider what the situation might be in a realistic failed alternator scenario.  

Are pitot heating requirements expressed in a standard design table, equations  or graph that would show heating requirements at various speeds and temperatures?

 

[dynonsupport]

Sorry, we don't have a table of speed vs. ambient temp vs. current draw. You'll need to do this test yourself if it's important to you.