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Old 27-02-2016, 13:45   #1
er9
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negative power supply and 12v negative battery supply same thing?

Trying to install dragonfly 5chartplotter. In instructions it says if no RF vessel ground available connect drain wire to negative side of vessels power supply. Is that another way of saying the negative post of the battery? The chartplotter has a red positive wire, a black negative and a grey drain wire. Do I simply wire the grey drain wire and the black negative wire together?
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Old 27-02-2016, 14:09   #2
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Re: negative power supply and 12v negative battery supply same thing?

you should wire the drain all the way back to the battery negative. so any spikes will drain.

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Old 27-02-2016, 14:22   #3
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Re: negative power supply and 12v negative battery supply same thing?

The drain wire is best connected back to the battery for best performanc ebut can be connected to the negative at your termination as well. Its important to only connect the one end to the negative. Personally I'd either leave it unconnected or connect it to the negative of the power supply, see if you get any interference and go to better conenction if you do.
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Old 27-02-2016, 20:59   #4
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Re: negative power supply and 12v negative battery supply same thing?

Much thanks will keep that in mind. I had to get it wired asap and found a suggestion on raymarines website andI ended up connecting the drain to the black negative and crimped them both together in a splice connector. They terminate to a single negative wire out from the otherside of the connector. It seems to work perfectly. I will keep an eye on interference and watch how it performs over the next couple of days.
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Old 28-02-2016, 11:10   #5
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Re: negative power supply and 12v negative battery supply same thing?

Your boat should have a common ground, usually the engine block. Try not to connect directly to the battery's negative.
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Old 28-02-2016, 11:48   #6
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Re: negative power supply and 12v negative battery supply same thing?

Quote:
Originally Posted by reed1v View Post
Your boat should have a common ground, usually the engine block. Try not to connect directly to the battery's negative.
I agree. The engine block,if it is connected to water via shaft & prop, is the better point for drain. The reason is that the purpose of the drain is to connect the cabinet/ckt board RF ground as close to earth(water) as possible & avoid having ANY current in this drain connection. The Neg power wire from the eqpt. to battery carries the same current back to the bat. neg. as the Pos. wire carries to the eqpt. from the bat. Pos.-(what goes out must come back).
The drain connection is to shield it's eqpt.(farraday cage) from induced electrical interference that may be radiating throughout the boat from other eqpt. AND to provide a clean path to earth for any static buildup from antennae.
Your Bat. Neg. wire carries current, so it is not "clean" as there are electrons "bumping" thru it.
Having said all this,99% of the time on recreational sized craft,there is little to no "electrical noise".,so you can get away with connecting the drain/cabinet earth to the Neg Bat terminal,the Neg power lead at the eqpt. or , often,not connecting it at all.

Cheers/ Len
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Old 28-02-2016, 12:53   #7
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Re: negative power supply and 12v negative battery supply same thing?

If it's not super clear in the instructions call or email customer service and ask for help, if you expierement and fry it you will most likely void any warrenty.
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Old 02-03-2016, 07:32   #8
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Re: negative power supply and 12v negative battery supply same thing?

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Originally Posted by deblen View Post
I agree. The engine block,if it is connected to water via shaft & prop, is the better point for drain. The reason is that the purpose of the drain is to connect the cabinet/ckt board RF ground as close to earth(water) as possible & avoid having ANY current in this drain connection. The Neg power wire from the eqpt. to battery carries the same current back to the bat. neg. as the Pos. wire carries to the eqpt. from the bat. Pos.-(what goes out must come back).
The drain connection is to shield it's eqpt.(farraday cage) from induced electrical interference that may be radiating throughout the boat from other eqpt. AND to provide a clean path to earth for any static buildup from antennae.
Your Bat. Neg. wire carries current, so it is not "clean" as there are electrons "bumping" thru it.
Having said all this,99% of the time on recreational sized craft,there is little to no "electrical noise".,so you can get away with connecting the drain/cabinet earth to the Neg Bat terminal,the Neg power lead at the eqpt. or , often,not connecting it at all.

Cheers/ Len
It worked but I did see interference on screen during my trip. Now that im back and have time im going to hunt down that ground on engine block and figure out how to connect to it.
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Old 02-03-2016, 09:06   #9
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Re: negative power supply and 12v negative battery supply same thing?

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It worked but I did see interference on screen during my trip. Now that im back and have time im going to hunt down that ground on engine block and figure out how to connect to it.
Suggest you run a separate single 12-14 AWG or similar size wire from eqpt. drain to the bolt on engine block that the Neg Battery cable connects to.
Use good marine stranded wire & good crimp terminals.

Cheers/ Len
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