Found a Diode ????

Taz59

Petty Officer 1st Class
Joined
Apr 10, 2003
Messages
304


In the middle of fitting a second battery so I bought a new change over switch,when I removed the old one inside the box that the switch is mounted in there is a diode it's all wired up,but what is it for.

Cheers

Taza


_________________
1997 Fourwinns 205 Sundowner
Volvo Penta 5.7 GLI
 
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jerryjerry05

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May 7, 2008
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18,036
Re: Found a Diode ????

Not absolutly positive?
But I think the diode is there for when the motors running and you switch batteries.
Some alternators will short if you disconect the power to the battery.

No instructions with the switch?
Contact the manufacturer??
 

Taz59

Petty Officer 1st Class
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Apr 10, 2003
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Re: Found a Diode ????

The battery switch fitted is for a single battery ?? I am about to fit a double switch.
 
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bruceb58

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Mar 5, 2006
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30,537
Re: Found a Diode ????

That's too small of a diode to act as an isolator especially since there is no heat sink. Would burn out in a heart beat.

What is it connected to? Looks like someone added it.
 

Walt T

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Mar 16, 2002
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1,369
Re: Found a Diode ????

Its a diode added to allow the volt meter or perhaps ammeter to run without providing a way to drain both batteries ( I don't know I'm just guessing). Whichever battery is 'on' that diode allows whatever equipment to function and not drain both batteries. You're right, it's small, therefore small equipment. I have done this many many times. Stereos are one thing people like to have on all night, along with anchor lights and fans in the cabin. I could be completely wrong here of course, but perhaps whatever was controlled by the diode is no longer there. Maybe it ran one of those vibrating bed things the previous owner stole from a motel once and instead of coin box for quarters it has the diode now.
 
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bruceb58

Supreme Mariner
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Mar 5, 2006
Messages
30,537
Re: Found a Diode ????

On Volvos, there are a couple diodes that control the fuel pump relay. Perhaps one of the originals waschanged out and this was put in. Should be pretty easy to trace down the wires.
 

Taz59

Petty Officer 1st Class
Joined
Apr 10, 2003
Messages
304
Re: Found a Diode ????

Guys
This is an orginal part fitted to the boat its all wired in as its part of the wiring loome,the selector switch is for single battery only,the boat is a 1997 Fourwinnns 205 Sundowner.The selector switch is mounted inside a metal box.
 

Fun Times

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May 16, 2009
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9,044
Re: Found a Diode ????

According to the owners manual the Brown/Red wires leads to the bilge pump from the switch. There should be a fuse at the switch. Possibly the diode is so the power will only feed one way vs back feeding into another circuit when activated.

Near the bottom of the link is an electrical schematic for your boat model. Also see all of section E for electrical systems,
http://www.fourwinns.com/upload/Documents/OwnersManuals/Earlier/1998-2000 200-240 Horizon.pdf

Also while I'm at it, It seems from your online photos, you run with a four winns group of boaters so maybe this link of four winns owners manuals may come in handy someday.:)

Four Winns
 
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