Thruster constant power drain question

[Woodstock]

I changed out our 24V thruster charger this week and when I was hooking everything up I noticed that there's a constant 20ma power drain on the batteries. The battery bank hooked solely to the Volvo QL Thruster Control Module so is isolated from all of the other battery and charging systems on the boat. Both helm controls were in the off position and the charger was not connected (fuse disconnected). It's a small drain and there is a separate thruster battery disconnect switch in the ER if I want to stop it but is this constant power drain normal?

 

[boatpoker]

How long do your thruster anodes last ?

 

[O C Diver]

Depending on how the electronics in the controls are configured with a computer chip, there could normally be a small drain. Also one on the controls could have a faulty chip. Try analyzing it again with one and both or the controls unplugged.

Ted

 

[High Wire]

Depends what components are inside the "module". 20 ma is less than a miniature light bulb. It would take 50 hours powered up 24/7 to equal one amp-hour. The question is "Is it leakage or normal?". If you disconnect the motor leads to the thruster and just leave the power to the control panels, does it stay or go?

 

[Woodstock]

Thanks for the replies. Very little wear on the thruster anode. I don't think it's leakage as I measure exactly the same ma on the negative side of the battery. I will try disconnecting a motor lead to see if it makes a difference.

 

[Arc]

.020A my just be the control head at rest.most controls have a plug and socket. Just disconnect and test

 

[C lectric]

YOu might want to go through the manual looking for power specs.

My radar has a continuous draw to keep the control panel active to sense when I push the On/Off button at the least. That's often the way electronically controlled devices are built especially where the ON/OFF button is not a mechanical switch.

This is not the only device built like that. My two sounders are the same and although I have not checked I'll guess my GPS is the same.

GHOST loads.

In my manual they said if that was not acceptable then install an actual switch to shut off power completely.

They can be battery killers left long enough.

Yours may be similar.

 

[Pete Meisinger]

My alternator had a similar drain. Didn't concern me as it was so tiny I didn't even know it was happening until one winter it actually killed a battery.

It went away when I had the alternator rebuilt.

pete

 

[JDCAVE]

How long do your thruster anodes last ?

I wonder about this as well. My thruster anodes don’t hold up well at all and I wonder if there is some small draw somewhere as well. It’s on the “list”.

Jim

 

[sunchaser]

I wonder about this as well. My thruster anodes don’t hold up well at all and I wonder if there is some small draw somewhere as well. It’s on the “list”. Jim

JD
How long do your thruster anodes last? We get about two years as noted by an annual spring haul out and end of summer diver cleaning.

Also, if you have a isolator switch between your battery and thruster you can mitigate incipient potential thruster draw. Any dock snow yet?

 

[C lectric]

I wonder about this as well. My thruster anodes don’t hold up well at all and I wonder if there is some small draw somewhere as well. It’s on the “list”.

Jim

Zinc size has a lot to do with the "lasting". There may not be enough room on the shaft or nut to allow a larger zinc.

There is a silver/silver chloride 1/2 cell available from Boatzincs.com {RED LEAD} which can then be used to check that the zinc is working and the voltage it produces. As the zinc wastes away the voltage will drop. There is a voltage limit beyond which it is time to change the zinc. The cell only is used with a DMM along with a neg [BLACK] lead which you will have to fabricate with a probe or a med. sized alligator or bulldog clip.

https://www.boatzincs.com/corrosion-reference-electrode-specs.html

I bought one years ago and it has served me well. It tipped me off to a couple of developing problems before they actually became a serious problem. I can also monitor the zinc wasting as they age.

 

[C lectric]

I wonder about this as well. My thruster anodes don’t hold up well at all and I wonder if there is some small draw somewhere as well. It’s on the “list”.

Jim

Zinc size has a lot to do with the "lasting". There may not be enough room on the shaft or nut to allow a larger zinc.

There is a silver/silver chloride 1/2 cell available from Boatzincs.com {RED LEAD} which can then be used to check that the zinc is working and the voltage it produces. As the zinc wastes away the voltage will drop. There is a voltage limit beyond which it is time to change the zinc. The cell only is used with a DMM along with a neg [BLACK] lead which you will have to fabricate with a probe or a med. sized alligator or bulldog clip.

https://www.boatzincs.com/corrosion-reference-electrode-specs.html

I bought one years ago and it has served me well. It tipped me off to a couple of developing problems before they actually became a serious problem. I can also monitor the zinc wasting as they age by tracking the falling voltage.

 

[JDCAVE]

SC: I sort of get a year on my aluminum anodes with use mostly in freshwater. They probably should be changed sooner but I change them when the boat is out of the water. Your comment about a switch between the batteries and the thruster bank is an option, except they are under the master berth. I should check for a small amperage draw.

Thanks “C” for your advice. I will look into the silver chloride electrode, although I had thought they are best used in saltwater.

Jim

 

[twistedtree]

That appears to be a wireless controller? If it has any sort of electronic control then a 20ma draw is understandable, though a bit of a nuisance.


You mention a battery disconnect switch. I'd just add "Disconnect thruster battery" to your checklist when leaving the boat for any prolonged time.

 

[C lectric]

As TT says, if the unit is wireless then the receiver AT your thruster controller must be on all the time unless you provide a mechanical shutdown like a battery switch.
I didn't realize yours was wireless but this is more and more common on all kinds of electronic devices. Some part of the control MUST remain active all the time even if just to sense your activation of "ON" or "You want me to do something?"

Ghost Load.

The silver cell is useable in brackish water and "fresh" water. The voltage generated will be lower due to the lower salt content but there will still be a voltage. When the zincs are new check them for the baseline reading. In your case the readings may be affected by the salt/fresh water mix ratio at different times so the reference and also when out in the ocean.
That ratio change will affect your reading more than mine where I am.

Generally I have never had a problem with zinc quantity on my boat. What I have had is somehow something became unbonded. A poor connection over time showed up, a poor installation where the zinc to metal connection was lost. I found those problems before they caused a problem other than me sorting out how to Mickey Mouse untill the next haul out.

 

[bill.kimbell]

Any chance there is an automatic bilge pump direct wired in that battery/bank? They wire them in surprising places to avoid battery switch.