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Old 18-06-2014, 01:02   #1
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Switch battery pos or both pos and neg

I'm getting ready to rewire my pocket cruiser. I have a Blue Sea 5501e dual circuit battery switch and I'm wondering how I should wire it to the battery. Since this switch can switch 2 isolated circuits, should I just switch the positive lead from the battery, or both the positive and negative leads from the battery? Here's some additional background on my boat. It is a Lockley Newport 19' sailboat, I have only 1 12v battery and my outboard does not have electric start so there is no electrical connection to the outboard whatsoever. I currently use the boat only for daysailing and it spends 90% of it's time out of the water on the trailer. I charge the battery with a portable charger when it's on the trailer. Is there an advantage to disconnecting the battery from the boats electrical system completely by switching both the positive and negative leads for the extended periods it will sit idle? Or should I stay with the traditional switch the positive only setup? Thanks in advance for your experienced advice.
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Old 18-06-2014, 01:14   #2
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Re: Switch battery pos or both pos and neg

I don't see anything gained by running the neg cable through the switch. And anyone following you would be confused by it.
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Old 18-06-2014, 07:20   #3
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Re: Switch battery pos or both pos and neg

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Originally Posted by mjsrebin View Post
I'm getting ready to rewire my pocket cruiser. I have a Blue Sea 5501e dual circuit battery switch and I'm wondering how I should wire it to the battery. Since this switch can switch 2 isolated circuits, should I just switch the positive lead from the battery, or both the positive and negative leads from the battery?...
You'd better learn something about electricity before proceeding, at least the basics. Or hire a pro. Connecting both positive and negative to a battery switch could result in an explosion.
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Old 18-06-2014, 07:26   #4
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Re: Switch battery pos or both pos and neg

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Originally Posted by Ex-Calif View Post
I don't see anything gained by running the neg cable through the switch. And anyone following you would be confused by it.
What he said .
Seriously, Ex-Calif is correct.
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Old 18-06-2014, 08:07   #5
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Re: Switch battery pos or both pos and neg

TerraNova,

I think you misread the OP's question, possibly because he mis-typed the model number.

He has a Blue Sea Systems DUAL-CIRCUIT battery switch, probably the 5510e (not the 5501e).

These can handle two independent circuits and do not combine them.

However, I agree that in his case there's no advantage in switching the negative as well as the positive. European's like to do this, but in this case there's no apparent advantage and there's the disadvantage of additional wiring, connectors, and the possibility of an inadvertent short.

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Old 18-06-2014, 08:49   #6
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Re: Switch battery pos or both pos and neg

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TerraNova,

I think you misread the OP's question, possibly because he mis-typed the model number.

He has a Blue Sea Systems DUAL-CIRCUIT battery switch, probably the 5510e (not the 5501e).

These can handle two independent circuits...
The battery switch will handle 2 independent POSITIVE circuits--NOT positive and negative.
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Old 18-06-2014, 09:07   #7
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Re: Switch battery pos or both pos and neg

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The battery switch will handle 2 independent POSITIVE circuits--NOT positive and negative.
No. The switch doesn't know whether it's positive or negative. You could wire one of each. I wouldn't.

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Old 18-06-2014, 09:15   #8
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Re: Switch battery pos or both pos and neg

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No. The switch doesn't know whether it's positive or negative. You could wire one of each...
Let me know how that works out for you.
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Old 18-06-2014, 09:37   #9
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Re: Switch battery pos or both pos and neg

Here's the diagram for the 5510e from the Blue Sky website.

Technically the positive and negative cables could both be opened together with this one X two position, non-combining switch.

But it is unnecessary and would be confusing to anyone who came after. And as an aside it would add two more connections in the ground circuit that can loosen and corrode.

There is only one other reason to isolate the negative cable (and I wouldn't do it this way) and that is if anything is wired directly to the battery and you no kidding want all the power off the boat.

Some things that may need continuous power and are not switched are bilge pumps, clocks and a few other things maybe but OPs boat is simple and stored in a trailer so he likely has nothing that needs unswitched power.

So now you have some info - what you do with it is up to you. I wouldn't do it.
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Old 18-06-2014, 10:44   #10
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Re: Switch battery pos or both pos and neg

You can do it but I don't see much gain in doing so. At work we on occasion, for military and work vessels build panels this way (DC + and DC- switched) but this is usually on steel or aluminum hulls with floating grounds so that everything can be isolated. I don't believe we have used the blue sea switch but I know we have done it with the BEP version. As said before if the switch has a combine position this would be a bad idea.

On a side note new Beneteaus and Lagoons seem to have a separate battery switch for the DC grounds. Not sure the reasoning but it can be pretty annoying if you forget to turn it on.
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Old 19-06-2014, 01:16   #11
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Re: Switch battery pos or both pos and neg

Thank you everyone for your good advice. After doing a bit more research I agree that Blue Sea probably included switching both positive and negative for the sake of steel and aluminum hulled boats with the ground isolated from the hull. I will probably only switch the positive based on your advice here.

For TerraNova, please refer the the following instructions from Blue Sea provided with the battery switch, note that they refer to switching both positive and negative of a battery bank along with a nice picture illustrating such a setup.

http://assets.bluesea.com/files/reso...eb_version.pdf

Perhaps you should research the topic in question some before starting your rant next time.
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Old 20-06-2014, 21:46   #12
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Re: Switch battery pos or both pos and neg

The 5510e does not combine the 2 circuits, whereas the 5511e does have the capability to combine.
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