dodsworth
New Member
should the bilge pump be connected directly to the battery so that when you leave the boat with the electricts switched off it will still work
bilge pump
- Thread starter dodsworth
- Start date
fibz99
Well-Known Member
thru a float switch, yes. Well i do.
Oldhand
Well-Known Member
and through a fuse.
fisherman
Well-Known Member
But bear in mind that there will be residual current in the negatives in the whole system unless you isolate the negative from the battery as well.
pvb
Well-Known Member
[ QUOTE ]
But bear in mind that there will be residual current in the negatives in the whole system unless you isolate the negative from the battery as well.
[/ QUOTE ]Care to expand on that?
But bear in mind that there will be residual current in the negatives in the whole system unless you isolate the negative from the battery as well.
[/ QUOTE ]Care to expand on that?
sarabande
Well-Known Member
It's the Stannary Effect, whereby a virtual circuit can be physically active, providing the legpull remains constant. /forums/images/graemlins/grin.gif
fisherman
Well-Known Member
[ QUOTE ]
[ QUOTE ]
But bear in mind that there will be residual current in the negatives in the whole system unless you isolate the negative from the battery as well.
[/ QUOTE ]Care to expand on that?
[/ QUOTE ]
You can turn all your electrics off by isolating the +tive to the battery and leave the auto bilge pump on. When it fires up the residual current in the neg coming back from the pump goes to every circuit in the boat, unless you isolate the battery neg also. If there is damp, not unknown on a boat, you might get a bit of +tive leaking from the auto switch connections. As the wires to these switches are always short, and need connections in the bilge, this is a common occurrence. Sometimes the switch itself leaks a little current into the bilge water, unless really well sealed.
[ QUOTE ]
But bear in mind that there will be residual current in the negatives in the whole system unless you isolate the negative from the battery as well.
[/ QUOTE ]Care to expand on that?
[/ QUOTE ]
You can turn all your electrics off by isolating the +tive to the battery and leave the auto bilge pump on. When it fires up the residual current in the neg coming back from the pump goes to every circuit in the boat, unless you isolate the battery neg also. If there is damp, not unknown on a boat, you might get a bit of +tive leaking from the auto switch connections. As the wires to these switches are always short, and need connections in the bilge, this is a common occurrence. Sometimes the switch itself leaks a little current into the bilge water, unless really well sealed.
pvb
Well-Known Member
I've never fully subscribed to the belief that the PBO forum largely consists of people who don't know what the [--word removed--] they're on about, but posts like yours do make me wonder if I need to review my position.
fisherman
Well-Known Member
Well I bow to your superior knowledge, but over the years I have learned to dislike leaving anything switched on when the boat is unused/cold/damp. There is live +tive to the float switch all the time, and I have always found the wires to be too short to get the connection somewhere dry. Last thing I would want is any current in the bilge water, and the float switch will be submerged if it is to work. I have been given to understand that there is residual current in the negative back from the pump when it is running, and if the battery neg is still connected to the services that current will run round the boat. Unless you can enlighten me otherwise.......
I find your slightly opprobrious tone upsetting, and may burst into tears.,
I find your slightly opprobrious tone upsetting, and may burst into tears.,
pvb
Well-Known Member
\"run around the boat\"...
[ QUOTE ]
...there is residual current in the negative back from the pump when it is running, and if the battery neg is still connected to the services that current will run round the boat
[/ QUOTE ] So if the positive feed to the main circuits is disconnected at the main switch, just where do you think this so-called "residual current" is going to run to?
[ QUOTE ]
...there is residual current in the negative back from the pump when it is running, and if the battery neg is still connected to the services that current will run round the boat
[/ QUOTE ] So if the positive feed to the main circuits is disconnected at the main switch, just where do you think this so-called "residual current" is going to run to?
cliffordpope
Well-Known Member
Re: \"run around the boat\"...
I think all Fisherman is saying is that in a damp environment, like a boat, any fault in the wiring can cause leakage of current to earth, and even a small leakage can over time flatten the battery or cause corrosion.
In dry conditions the state of the wiring and connections is not so critical. Look at the way car lights start behaving oddly once you have a jumble of wires and connections sitting in water in a leaking boot or inside a muddy/salty/rusty wing.
I think all Fisherman is saying is that in a damp environment, like a boat, any fault in the wiring can cause leakage of current to earth, and even a small leakage can over time flatten the battery or cause corrosion.
In dry conditions the state of the wiring and connections is not so critical. Look at the way car lights start behaving oddly once you have a jumble of wires and connections sitting in water in a leaking boot or inside a muddy/salty/rusty wing.
pvb
Well-Known Member
Re: \"run around the boat\"...
What Fisherman actually said was "When it fires up the residual current in the neg coming back from the pump goes to every circuit in the boat, unless you isolate the battery neg also." It's just nonsense.
What Fisherman actually said was "When it fires up the residual current in the neg coming back from the pump goes to every circuit in the boat, unless you isolate the battery neg also." It's just nonsense.
fisherman
Well-Known Member
Re: \"run around the boat\"...
I suppose I should have said 'can' run around the boat. I was told that leaving the bilge pump on auto could be the cause of terminals around the boat becoming corroded due to residual current in the negs. However, if it's nonsense, fair enough.
I suppose I should have said 'can' run around the boat. I was told that leaving the bilge pump on auto could be the cause of terminals around the boat becoming corroded due to residual current in the negs. However, if it's nonsense, fair enough.
cliffordpope
Well-Known Member
Re: \"run around the boat\"...
It's not necessarily nonsense.
Because a boat (unlike a car) does not have a conducting chassis that can be used as an earth to complete each circuit, every electrical component will have to have two wires going to it, negative and positive.
Turning off the positive say will normally isolate the component. But the negative will still be connected to the battery, so could therefore have an electrical potential with respect to anything else nearby that was not also at battery negative potential. So if there was a poor connection or insulation in a component that was switched on, ie connected to battery positive, the bilge water or damp hull could have a slight positive potential, because of leakage.
It merely shows that in a damp environment nothing can be taken for granted.
It's not necessarily nonsense.
Because a boat (unlike a car) does not have a conducting chassis that can be used as an earth to complete each circuit, every electrical component will have to have two wires going to it, negative and positive.
Turning off the positive say will normally isolate the component. But the negative will still be connected to the battery, so could therefore have an electrical potential with respect to anything else nearby that was not also at battery negative potential. So if there was a poor connection or insulation in a component that was switched on, ie connected to battery positive, the bilge water or damp hull could have a slight positive potential, because of leakage.
It merely shows that in a damp environment nothing can be taken for granted.
