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Old 03-28-2013, 03:29 PM   #11
Join Date: Aug 2010
Location: Purcellville, VA.
Posts: 296

Todd, you can use a test light for draw as well. Just disconnect the negative cable from battery and connect the test light between the battery and the negative cable. The light will come on and the brightness of it will increase or decrease with load level.
I like using a light as it is easier to see from afar
Are you sure there are no other connections at the battery? I would assume that you have 1 positive and 1 negative cable going from the battery to the switch. You state that the bilge is hot too so there must be those cables connected to the battery as well, are there any others or just those? They could also have connected some wires to the input side of the switch so check there too.
Could there be corrosion inside the switch causing some voltage leak across the Off and On positions?
All it really takes is radio clock/memory draw to cause a spark and if that is all of it, the light will barely be lit when connected between the cable and battery.

So to clarify, disconnect negative cable from battery.
Connect alligator clamp from test light to battery post.
Jam the probe end of the test light into the cable end (normally you can wedge it in the stud hole).
Let there be light :-)

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Old 03-28-2013, 05:24 PM   #12

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There are any number of devices that, even when "off", are still drawing power; the radio is a prime example. The radio will probably have a red/+ (main power), black/-, and yellow/memory. Red/+ (main power) could be wired to a switched source, like the ignition or battery switch, but the yellow is supposed to be wired to an un-switched 12V source. Some amplifiers are also set up to switch to "stand by" mode when the radio is turned off.

Mechanical bilge pump float switches don't draw any power, they just close/complete a circuit. An electronic one might, and a high water alarm also might. I suppose it's possible that a switch might have enough crud built up on it that it might bridge, allowing some current to pass, but nto too likely.

Regardless, pulling the fuses one at a time should find it. I'd start with the radio though.

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Old 03-31-2013, 08:32 PM   #13
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Location: Chesapeake, VA
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Do you have anything connected directly to the battery? Are there any small black or red wires connected to the battery terminals? If so, they are drawing a load. Probably nothing to worry about but you may want to fuse them if you're concerned.
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Old 04-01-2013, 01:15 PM   #14
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There are things connected directly to battery. However they are not drawing any power. (ie: trailer switch is connected to battery but does not draw power till the switch is pushed.)

I hope to do a "draw test" same as you would on a car next weekend. Ill keep everyone posted on how to do this test and ill post pictures as well.


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