TOPIC: Any electrical gurus here? Opened my Can O' Worms.

Well, I'm moving the Mercontrol higher so it can be operated while standing, or at least stooping. I needed to reroute the cables and wires, so I opened up the Mercontrol...and..(UGH) all the wiring insulation just fell apart.

I can't find a matching voltmeter, so I'm going to take this opportunity to install the matching ammeter and fuse everything. I'm confused as to the wiring from the rectifier to the switch box. I'm planning on wiring it like I have below. I'm also not sure if I should put a fuse in the wire going to the switch box as that wire is also the stator wire.

I'll be using all new 10ga wire. I just left the old wires on the schematic to clarify what was existing. I also used this schematic instead of the one for my 1250 because this matches my engine wiring harness - the red batt wire tee's off and goes to the rectifier and the switch box.

Thanks,
Mark

Mark,

The wires to the stator usually aren't protected by a fuse. The rectifier is fused in case there is a short. I don't know how many amps that alternator can kick out, but I doubt it's over 20. May want to put a 20 amp fuse between the + rectifier output and the ammeter. If you haven't made the harness yet - large trucks and trailers use multi-lead cable that looks a lot like the original stuff the engine used. You can get 5, 7, 9, lead cable for less than it will cost to buy bulk wire. I get mine at NAPA auto parts here in California. You may want to look into using that.

Thanks Bruce. I ended up rewiring the whole boat this weekend. I used the old boat harness and cut almost two feet off and re-soldered all connections and abandoned the battery feed on both ends. Then I ran new runs for everything else in 10ga. with no fuse for the alternator output. I installed a main fuse at the battery and a 4-circuit panel.

The truck harness is a great idea! I wish I knew about it. But it turned out ok - Good news: my tach and electric choke now work! Bad news - Just received my NOS tach in the mail and the ammeter doesn't work

Also, I learned this weekend that a very thin layer of corrosion on contacts will create a non-op condition. Every switch and every light bulb did not work because of that. It didn't even look bad.

Thanks again,
Mark

Congratulations on getting all that accomplished. I wish I had time to work on mine.....

As for the corrosion, you can put a film of grease on light bulb bases, and on electrical connections to protect them. Silicone based grease works well, or any heavy grease will help.

Thanks Bruce, I'll do that

the best is called dielectric grease. It comes in small tubes and is rather expensive (8-9 bucks a tube), but is by far better than just any old grease because it is electrically conductive, and keeps the corrosion out. But one rule is that anywhere you have electricity flowing on a boat, you are going to get corrosion. All contacts and connections need to be cleaned and grease annually. More often on saltwater.

Ike wrote:

the best is called dielectric grease. It comes in small tubes and is rather expensive (8-9 bucks a tube), but is by far better than just any old grease because it is electrically conductive, and keeps the corrosion out. But one rule is that anywhere you have electricity flowing on a boat, you are going to get corrosion. All contacts and connections need to be cleaned and grease annually. More often on saltwater.

Thanks Ike