Rewire Project

sludgeguy68

Petty Officer 2nd Class
Joined
Jul 16, 2010
Messages
111
The wiring on this boat (18' checkmate) was a mess - nothing was fused, everything spliced into the panel with electric tape, and the battery had giant stacks of ring terminals - it was tough to get the wing nut on the battery even. After my lights shorted out on the water one night, I made it a point to rewire it over the winter.

I'm putting in a new stereo system, gauges, and interior lighting with LED strips.

The gauges are a little odd I guess - the jack plate and water pressure gauges only need to be powered on with the key (why use the extra volts right?), and I want to be able to see my volts and fuel whenever the master switch is on (i.e. I'm in the boat on the water).

The head unit power will be controlled via the switch panel so I can ensure that the head unit and, more importantly, the amp is powered OFF when done for the day... even if I forget the helm switch the master switch will take care of it. I will be testing battery draw a bunch of times this spring to see if I can get by with just one battery.

Please let me know what y'all think

Wiring diagram: http://i.imgur.com/MppUeBQ.jpg
 
Joined
Feb 17, 2012
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2,906
Re: Rewire Project

looks ok im wondering why you would want to see the fuel gauge with the motor is off as its not using fuel when its not running. I would leave the gauges and the gauge lights connected to the motor harness then add a small digital meter for voltage as they have a very low amp draw and are easier to read. i like 2 batterys when using a stereo with a amp but thats a personal thing either way you will need to have a plan B way to start the motor.
 

Auger01

Petty Officer 1st Class
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Aug 15, 2009
Messages
201
Re: Rewire Project

The drawing looks good. If it was mine, I would fuse the 10 Ga wire going to the fuse block with a 30 amp fuse. I don't know if a 400 watt amp actually draws 400 watts, but that would be 33 amps at 12 volts.
 

Don S

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Re: Rewire Project

What is the output from the motors charging system?
On your jack plate, you might want to consider using a relay back near the jack plate, then you only need small gauge wiring and switch at the helm.
I would also add either bus bars or terminal posts at the back so you only have a single cable going to the battery instead of the 4 of each you have.

I also agree with the above that the engine instruments and gauge lights need to be on the motor harness, not your house system.

Adjusted drawing. https://www.dropbox.com/s/h5oak27lnsso04h/SG Wiring.pdf
 

Silvertip

Supreme Mariner
Joined
Sep 22, 2003
Messages
28,758
Re: Rewire Project

If you don't want a separate voltmeter, just add a momentaryswitch that feeds 12 volts to the existing voltmeter. It can then be checked at any tme without turning the key on and will not be an issue when the engine is running.
 

sludgeguy68

Petty Officer 2nd Class
Joined
Jul 16, 2010
Messages
111
Re: Rewire Project

looks ok im wondering why you would want to see the fuel gauge with the motor is off as its not using fuel when its not running. I would leave the gauges and the gauge lights connected to the motor harness then add a small digital meter for voltage as they have a very low amp draw and are easier to read. i like 2 batterys when using a stereo with a amp but thats a personal thing either way you will need to have a plan B way to start the motor.

Yeah I figured fuel gauges aren't normally wired like that, but I like to fuel up at my own dock when I get a chance, and don't want the motor running just to see when I'm topped off. I already have the tach+volts multifunction gauge as I didn't want to cut more holes in my already-crowded dash for a separate voltmeter. Yup I'm going out a whole bunch of times with an extra battery just in case - if I need it often, I feel like I can rig this to a dual battery setup easily for a better solution. I don't plan on blasting the radio.

The drawing looks good. If it was mine, I would fuse the 10 Ga wire going to the fuse block with a 30 amp fuse. I don't know if a 400 watt amp actually draws 400 watts, but that would be 33 amps at 12 volts.

Ah yeah I figured the 8ga was overkill, but it was already installed on the boat with the old amp - may as well use it!

What is the output from the motors charging system?
On your jack plate, you might want to consider using a relay back near the jack plate, then you only need small gauge wiring and switch at the helm.
I would also add either bus bars or terminal posts at the back so you only have a single cable going to the battery instead of the 4 of each you have.

I also agree with the above that the engine instruments and gauge lights need to be on the motor harness, not your house system.

Adjusted drawing. https://www.dropbox.com/s/h5oak27lnsso04h/SG Wiring.pdf

Checked my manual - it's supposed to put out 7-9 amps at the battery at WOT, however I would like to measure this to ensure it is working properly (rectifier was just replaced).

Interesting, I hadn't thought about a relay, sounds a lot neater. The original setup is like what I have in my diagram - those 10 gauge wires crammed onto the switch in a tiny 6-gang panel, yeah it seemed weird when I saw it - I didn't feel comfortable changing it since I'm new to electrical systems.

Could someone point towards an appropriate relay? I'm only seeing blade type ones that go in cars.

Good call on the 30A for house circuit!
 

Don S

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Re: Rewire Project

The switches in those panels are only good for 10 to 15 amps at most, not 30.

Could someone point towards an appropriate relay? I'm only seeing blade type ones that go in cars.

It actually takes two relays, you can by the relays and prewired sockets all over the place. Here is just one quick example on ebay Click Here

Here is a wiring diagram I did for trim up and down, but you just have a jack plate, just change the picture.

Trim.jpg
 

Don S

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Re: Rewire Project

Checked my manual - it's supposed to put out 7-9 amps at the battery at WOT, however I would like to measure this to ensure it is working properly (rectifier was just replaced).

Here's the thing, at max you will get 7-9 amps per hour out of your charging system, realistically, 7 max. Note that is PER HOUR

Your sound system amp uses a max of 33A per hour if it converts out right, that is 33A per hour it uses.

So at max power on the stereo, plus anything else you are running at the time, your engine dies for lack of electricity in about 2 hours or so.
 

gm280

Supreme Mariner
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Jun 26, 2011
Messages
14,585
Re: Rewire Project

Not sure how you are going to place your fuses or circuit breakers, but I'd put that main fuse or breaker (the 30 amp) in the actual battery box myself. That way there are no wires going to possibly chaf somehow and cause a huge short and maybe caught fire before the first fuse. After you come from that first fuse, wire anyway you like. But that first protection fuse needs to be as close to the actual battery as possible just for safety. I use to actually install the water proof fuse holder into the top cover of the battery box in my boat setups.
 

Don S

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Re: Rewire Project

Not sure I would want to put a fuse "IN" a battery box. Seen too many full of water.
Using the proper type fuse and mounting them to the transom along with bus bars, battery switches etc. is the best way to do it.
 

Auger01

Petty Officer 1st Class
Joined
Aug 15, 2009
Messages
201
Re: Rewire Project

Not sure how you are going to place your fuses or circuit breakers, but I'd put that main fuse or breaker (the 30 amp) in the actual battery box myself. That way there are no wires going to possibly chaf somehow and cause a huge short and maybe caught fire before the first fuse. After you come from that first fuse, wire anyway you like. But that first protection fuse needs to be as close to the actual battery as possible just for safety. I use to actually install the water proof fuse holder into the top cover of the battery box in my boat setups.

Along those lines, ABYC (American Boat and Yacht Council) specifies 7" max from battery to fuse. unless some type of conduit is used.
 

gm280

Supreme Mariner
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Jun 26, 2011
Messages
14,585
Re: Rewire Project

Not sure I would want to put a fuse "IN" a battery box. Seen too many full of water.
Using the proper type fuse and mounting them to the transom along with bus bars, battery switches etc. is the best way to do it.

Most any quality gasketed (if that is a word) fuse holder can be mounted on the actual top of any battery box without any problem. If you have any battery box that fills up with water, you do have a problem since those battery terminals would also be under water themselves then. But attaching the fuse in the top precludes any water from actually getting to that fuse holder itself. I have run many boats wired that way and never a problem. Of course my boats usually received more attention than the usual owner for sure. I owned most bass high performance boats. They stayed in a garage when not on the water and was always cleaned and in show room condition with every trip. I even would raise and wax the areas under the bunks to keep it immaculate all the time. I never ever wanted even a little problem when I went fishing. Yes I spent more time cleaning and prepping them then actual water time. But it was show room condition when I sold it to the very first person that came to buy it 10 years later. They actually thought it never seen water......
 

Don S

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Re: Rewire Project

If you have any battery box that fills up with water, you do have a problem since those battery terminals would also be under water themselves then.

I have been a marine tech for over 25 years, and trust me, battery boxes do fill up with water, but the tops of the battery are above the edge of a box. Fuses tend to get slid down inside the box next to the battery, which is why I said it wasn't a good idea to put it in the box as you first said. I never said anything about putting it on top of the box as you are now saying.
 
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