Automatic float question

[Keith7481]

I've been reading through the forum looking at some of the discussions about float switches and bilge pumps with the built in float switch. I recently picked up my boat from my mechanic who I had doing some minor work and had asked him to look at the float switch that I thought was sticking 'on'. He stated he tested it and found it worked correctly, he had filled the bilge etc. to test it. When I brought the boat home, I had to hook up the #1 battery, which I had disconnected because of my fear that the switch was sticking on and going to run the battery down, I trailer the boat. With the ground wire connected, I touched the red lead to the positive terminal and saw a small spark, but the pump did not run. As my battery selector switch was set to off, I was surprised. There was no water in the bilge, and as far as I know, nothing else should be able to run off the #1 battery beside the bilge pump via the float switch. So, I'm thinking my mechanic is wrong, or the there is always a small current going to the float switch when off, or I have an electrical problem with something else. I"ve read the posts on doing the battery drain tests and have the multimeter ready, just wondering if anyone had any insights on why the float switch might draw power when the pump is not running? Thanks in advance.
Keith

 

[Fireman431]

Re: Automatic float question

I recently picked up my boat from my mechanic who I had doing some minor work and had asked him to look at the float switch that I thought was sticking 'on'. He stated he tested it and found it worked correctly, he had filled the bilge etc. to test it.

This is the correct way to test it. Fill the bilge with water. When the float *floats*, it will close the circuit and allow the bilge pump to push water. This should happen with any battery switches/ignition key off.

When I brought the boat home, I had to hook up the #1 battery, which I had disconnected because of my fear that the switch was sticking on and going to run the battery down, I trailer the boat. With the ground wire connected, I touched the red lead to the positive terminal and saw a small spark, but the pump did not run. As my battery selector switch was set to off, I was surprised.

Then I have to assume that you have 2 batteries. This being the case, one of 2 things could be happening:
1) Although the battery switch is in OFF position, all that does is disconnect the batteries from the systems on the boat. The batteries are still connected within the switch and you're getting a bit of current back through the cables. Completely normal
2) The batteries are still supplying power to some components on your boat, such as radios, bilge pumps, etc. which the previous owner or factory had intended to run separate from the battery switch. Completely normal.

So, I'm thinking my mechanic is wrong, or the there is always a small current going to the float switch when off, or I have an electrical problem with something else.

Yes, there should always be power supplied to the float switch when it's off. It has to have a power and a ground wire. Is your bilge pump buzzing or humming? If it's running, you'll know. Put your hand on the pump if there's any question and that will let you know if it's on (if hearing it is an issue).

just wondering if anyone had any insights on why the float switch might draw power when the pump is not running?

The switch shouldn't draw power when the pump isn't running, but there should be power going to the switch , even when the pump is off. That's what makes it come on when needed when no one is around.

 

[Keith7481]

Re: Automatic float question

Yes, this is a two battery system. When I connect the power to the #1 where I expect the float valve is full-time connected, I get a small spark, but no noise from the bilge pump, and nothing else is operating that I can see. So, unless I do the battery drain test with the multimeter, I'll wait to see if that battery turns up dead in a few days.....

 

[Fireman431]

Re: Automatic float question

Even in an automobile, when a battery is initially connected, there is...sometimes...a spark. That can also depend whether is was connected positive or negative first.

Other things hold intrinsic power such as ECU's, stereos, alternator/stators, etc.

Unless your battery is dying all of the time (and you're sure it's not a crappy battery), you might be chasing a problem that doesn't exist.

 

[seabob4]

Re: Automatic float question

Boy, I seem to be posting this a lot these days...

See how one lead of the float is always getting power...it's not using power, so there is no draw, until the bilge has enough water in it to raise the float, which will turn the pump on. Switches don't consume power, equipment does...

 

[Keith7481]

Re: Automatic float question

thanks for posting that diagram again, I did see it in the earlier post. I think Fireman is correct. I'm not going to do anything about this issue until my battery dies. I just put in a new set, and can always start up on #2 so am not really worried about it. If #1 shows up dead one day, I'll probably do the drain test as outlined in previous posts. Thanks all. Keith