Stus-List Battery/Wiring Problem?

Marek Dziedzic dziedzicmj at
Thu Aug 17 12:33:17 EDT 2017

It depends on how you look at it...

100 mA = 0.1 A. This means a 2.4 Ah draw for a day; almost 20 Ah for a week.

Now it depends how often you charge the batteries (with solar, you do it constantly, so it does not matter, but if you were to charge with your motor, it does) and how big is your bank (battery bank). If your battery bank is 400 Ah. that 20 Ah drain is not much to talk about, but if you have one battery (80 Ah?) and it is not the newest, so its capacity is lower, that 20 Ah might mean a difference.

I know I am splitting the hair a bit here...

1994 C270 “Legato”
Ottawa, ON

From: Dennis C. via CnC-List
Sent: Thursday, August 17, 2017 10:23
To: CnClist
Cc: Dennis C.
Subject: Re: Stus-List Battery/Wiring Problem?

First, move the positive supply to the bilge pump to one of the input posts on the back of your battery switch.  Nothing to do with your issue, just a good practice.

Second, do you have a stereo?  Could it be the memory pre-set retention supply?  Yellow wire from stereo to battery.

100 milliamps isn't a lot of draw.  Try it on a car or truck, you'll get about the same for the stereo and security functions.  It's called "parasitic current draw".

Dennis C.
Touche' 35-1 #83
Mandeville, LA

On Thu, Aug 17, 2017 at 8:32 AM, David Knecht via CnC-List <cnc-list at> wrote:
I had a suspicion of a power leak in my DC system so did some diagnostics yesterday.  I have a solar panel running when not on the boat, so it has not been a high priority to solve (the batteries are always fully charged when I get to the boat), but I wanted to determine if it was real.  I took all the negative leads off the batteries and then put my ammeter between the negative lead and the negative post of the house battery. I have a Blue Seas “add a battery” rotary switch which isolates the start battery from the house battery.  I normally leave this switch on so that the emergency bilge pump switch and LED courtesy lights will operate.  Those are the only things I know of that still work when the panel switches are all off.  I measured a 100 mA with the rotary switch on and all panel switches off.  I measured 0 mA with the switch off. I thought it might be the automatic bilge pump, but that is a mechanical float switch and disconnecting it had no effect.  So either I am getting current through the panel with all circuit breakers off or this somehow relates to the battery isolation in the Blue Seas ACR system.  Any thoughts from the geniuses on this list as to where to go next diagnosing this?  Also, is 100 mA a significant drain?  Thanks- Dave

1990 C&C 34+
New London, CT

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