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discharging battery

Old 04-19-2008, 06:15 AM
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Default discharging battery

My 2001 18 Dauntless with a 135 Optimax has been exhibiting some peculiar electrical problems since the end of last season and now at spring startup has me wondering.

The last time I used the boat back in November I was coming across the lake near wide open in moderate chop when the auto bilge lamp lit while under way. All seemed normal except that it stayed on for about 15 minutes all the way to the ramp. I listened to what I thought was the bilge pump dieing while putting the boat on the trailer and verifying that the bilge switch was in the off position.

I disconnected the battery and ended up winterizing the boat figuring I would deal with a new pump this season.

I made the mistake of just cutting the power leads without checking the pump while it was in the boat and just for kicks wanted to hear what a sick bilge pump sounded like so I connected it to a battery I leave on the boat for the winter. Much to my suprise it sounded normal. Reinstalled it verified that indeed it worked and thought that was the end of that.

Went out to dinner believing my spring startup had gone smooth and all was well. Wrong, as I was covering the boat after dinner I noticed the gauges were lit as though the motor would be running except there was no key in the ignition and it was indeed in the off position.

Any thoughts on where I should start? Thanks,Tony

One strange note I made while I had the pump cut out of the circuit was that there was no power at the leads from the boat side while the bilge switch was in the off position. I have noticed that in the past the bilge would go into the auto mode when there was enough water in the bilge signaling the pump to do its job.

Is this normal - should'nt there be power no matter what in the event the bilge float system detects water and activates itself?

Also now that I think of it the old battery I leave in the boat over the winter to lift the motor if need be had adequate power in it to lift and drop the motor when I picked up the boat for the spring start up routine of mine although it was in its usual weak condition.

Just seems odd the battery was not zapped of its power from a trickle drain after sitting for 4 -5 months.

Is there a way to measure if there is a small load on the battery with the boat and all switches in the off position?
Old 04-19-2008, 08:24 AM
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Default Re: discharging battery

What bilge pump? To check for drain on the battery pull the negative battery cable and put a multi meter between the battery terminal and the cable and if you show voltage there is something drawing power.
Old 04-19-2008, 11:22 AM
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Default Re: discharging battery

Sounds like pump is good but the float switch hinges have not been cleaned & exercised with WD-40 and lubed with teflon spray for awhile, so the float was knocked up by water jostling & stayed upin ON position( or the switch is internally shorted ON).

When you cut the power leads then reconnected perhaps you reversed - ground lead & postive lead from the dash switch so instead of the the dash manual mode switch being able to optionally supply power to the pump, power is going from the battery + post , through the stuck on float switch and (with reverse from normal current flow) sending power to the pump dash switch and the instruments the switch normally jumps 12v+ power off of. that would happen even when battery and ign. switches were OFF. Just a guess.

Here's typical wiring for pump & switches:
Old 04-19-2008, 11:58 AM
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Default RE: discharging battery

I have 2 positive leads and 7 negative leads going to the battery. When I put the multimeter in the circuit as suggested 3 or 4 of the negative leads tested in this manner indicate 11 - 12 volts on the meter. With the other 3 or 4 there is no voltage indicated.

I may cut the leads to the bilge pump and see if this indeed makes any different. I am puzzled as to why the gauges are showing a display when the ignition is not in the on position.

I am not real clear on how this pump activates in the event of the boat taking on water and automatically working. There is no float just an impellar.

I will report back my findings after taking the pump off the leads. However when I resoldered them I made sure red went to red and black to black. Just confirmed that after testing for a load.

Man I am stumped. Do not really understand AC or DC.
Old 04-20-2008, 05:48 PM
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Default Re: discharging battery

Well, you have a couple of things going on. To address one of them, SOMEWHERE in that bilge you have a water sensor to turn on the pump automatically. Most common are float switches, either built right into the pump (which is maybe why you didn't notice it) or located near the pump. Sometimes, however, they can be up to a few feet away. Also, there are other, more compact, sensors that don't have float action, but they are rare. Anyway, somewhere, you have something.

When you say "there was no power at the leads from the boat side while the bilge switch was in the off. ... should'nt there be power no matter what ... ? " the answer is "not necessarily." There are a number of different ways of wiring these bilge pump circuits, depending on a number of things, especially how the switch is configured. Is it just manual on/off, with the automatic function being fully automatic, or is it on/off/auto (probably more common) where in the off position, the pump will NEVER function no matter what. In this last case, you would not expect to find power at the pump leads when you cut them, if the switch is off. Even if the console switch is in auto, depending on the exact wiring between the pump, the sensor switch and the console switch, there might be no power at the cut leads.

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