Autohelm pilot current draw

Roberto

Roberto

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I have an autohelm pilot interfaced with a set of AH instruments and gps.

When on standby, with only the pilot ON, current draw should be 60mA according to the manual. When switching it on, I hear a click sound very much like a relay, which I suppose is inside the control box.
Instead of 0.06A I measured 0.50 A.

When switching on the instruments, which draw current directly from the pilot black box, consumption increases a bit but accordingly to the instrument current draw magnitude.

Is 0.5A a leak I should trace or is it more or less normal with these pilots ?
I reckon it is not too worrying, but after having stripped half the electrics of the boat to find the source of the half amper I would be happier to get rid of it..

thanks
 
The 60mA you've quoted is surely the current drawn by the instrument head itself? There'll also be current drawn by the course computer in standby. This might typically be another 300-400mA, so your actual figure of about 0.5A looks about right.
 
you dont gives us enough data to be able to advice - which autohelm, where are you measuring, does the second figure also include the rudder drive, is the rudder drive a linear drive, or hydraulic.

Larges draw from an 5000 or above system is the current to a linear drive - which can be well over 2 amps at times. Most raymarine manuals will provide details of the current draw for all the items, but it is the linear drive than will always demand the most - however this can be reduced considerably by making sure that the sails are balanced properly.
 
thanks pvb,

the manual of "Autopilot Control Unit" says
Standby: 60mA (less than 200mA with full lighting)
Auto: between 0.5A and 1.5A depending on drive type, boat trim, helm load and sailing conditions.
It states "Auto" mode is when the pilot is actually steering the boat.

In fact, except for flat seas and very little course corrections, consumptions are frequently much higher than the 1.5A they mention (I do not remember the exact figure but the fuse is something in the region 30-40A)

I don't know the internal principles of the pilot, but could it be that
1.the cliking sound is a relay which permanently energizes the motor,
2.as the control unit does not send any inputs to the steering motor, it shows "Standby",
that might explain the standby+higher consumption

or is it that the relay is activated only when a steering signal is sent ?

thank you
 
Talbot,

sorry, AH model is ST6000 plus, linear drive; I disconnected all other circuits and measured current draw from the battery directly to the pilot cable (really as if it were the only circuit in the boat).
The 0.5A figure is constant with the pilot in standby; whenever I set it to "Auto" current obviously increases following the rudder movements.
 
I would have thought the relay would be the switch to provide power to the drive unit's clutch, which should be active only when in AUTO mode. Strange that it should be ON immediately after powerup when it should be in standby. I take it you can move the wheel?

Are you sure the pilot has been setup for the correct drive type? For example if it was expecting a hydraulic pump type drive it might be powerup up the pump full time? Still I would expect you to find it difficult to move the wheel manually if this we so.
 
I hear the same clink on my 6000 autohelm, this is the clutch engaging and I understand the current draw is to keep the clutch in that position.
 
ST6000+....

The ST6000+ is just a control unit, which has to be connected to a course computer. You've probably got a Type 100/300 course computer, and I don't know what sort of current they draw. But the later generation of course computers (Type 150/400) quote a standby power consumption of 300mA. So, with the control unit drawing 60mA, and a course computer drawing 300mA or so, you're close to the 0.5A you've measured in standby mode.
 
Re: ST6000+....

We have a similar autopilot, but with different drive (ours is a motor driving a chain driven gear which works on a rack on an extra quadrant on the rudder stock.)

The motor makes a sound like a click of a relay when the autopilot is engaged. It is the magnetic clutch in the drive unit in our boat. (I know because I took the drive assembly appart to grease it last winter.)

Could it be a clutch mechanism in your linear drive, or perhaps linear drives don't have clutch mechanisms?
 
power for the Linear drive for that pilot requires between 1.5 and 3 amps of power when working, which is consistent with the fuse requirements.

You presumably have been measuring this additional power when the boat was at rest, so even if ruder was being moved, the power requirement to do so would be minimal. Try doin so when the boat is actually moving, and the rudder is being moved by the linear drive, and you will see a major increase in power consumption.
 
As others have explained the increased current is from the the drive, even though the computer/drive is in standby, and is nothing to worry about.

If the extra current draw is of concern to you because of restricted battery capacity on the boat then I believe (I recommend that you do a test with a temporary supply first to ensure that your system works this way) that the way to solve it is to keep your existing high current cabling to the computer and which also powers the drive but also place another switched 12v supply onto the DC line inside the Seatalk cable from the computer to your instruments. It can be cut in anywhere on the cable or parallelled at the SeaTalk terminals on the computer.

This only needs to be of enough capacity to power the instruments. When not needing the pilot just have that supply switched on, but not the high current one, and even though the computer will get power from the SeaTalk cable it will not engage the linear drive clutch.

When needing the pilot operational, switch on the high current supply that you now have and the drive will engage in standby as it now does. If you do not have this high current supply switched on and you do try to turn the control unit to "Auto" you will find that it will just stay in "Standby" politely refusing to indicate that it is in control.

Doing this also gives you a back up power supply to the instruments.

John
 
thank you very much everyone!

from your informations I understand that current draw comes from the drive clutch/computer course, indeed there are four cables coming from the mechanical linear drive (two for the motor and two for the clutch) to the Type 100/
300 course computer,


anyway, clutch-drive-computer I am happy the half ampere is coming back to the battery and is not lost all over the place in the boat, which is comforting -.<)


John, good idea, I will certainly add the separate feed for the instruments,


thanks again

rob
 
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