I would be curious to see the actual current
draw from an AP under duty in different conditions. The AP I have (Alpha3000) has the ability to control "yaw" and response to "sea state". In flat seas and motoring with the AP, for example... the helm
is not moved at all. I imagine that the current
draw is mostly then the processing of the compass
data and the feedback data from the ram drive. It would be very low under these conditions. As seas build the AP will make more corrections to maintain course. Puffs of wind of course will cause the boat to head
up for example and the AP needs to correct for this as well. So the heavier the conditions... the more work the AP does and the more current it draws to do this. With the Alpha you adjust to the controls to find the right balance.... between corrections and course.
And of course current draw is not an issue when there is charging of the batts taking place which exceeds or matches the current draws... such as motoring, wind and or solar.
What would be interesting would be to see a plot of AP current use compared to wind and sea states.