Misc notes: Wiring for the New Engine
July 2006 -
As part of the repower I have to replace all the wiring I ripped out last year.
The Big Wires for charging are a pain to crimp, because a proper crimping tool costs hundreds of dollars. Fortunately, my local boatyard chandlery has the right crimping tool right there, and anyone can use it.
I have the cheap Ancor crimping tool that you crunch down
with a vise (or vise grips,) and it'll do in a pinch, but this one makes a
Along with the repower, I'm finally installing the regulator
part of my Xantrex Link 200R.
There wasn't any point before,
because the Ample Power voltage regulator
was working fine. It just wasn't
integrated with the rest of the system.
The power wire, as well as both wires from the shunt, require fuses because they're coming straight off of the alternator. I used little in-line waterproof holders, because I like to hose down the back end of the boat every now and then.
With two wires, a single waterproof cover can be used on each half, making it easy to install without cutting the little rubber thing. Once installed, the wire twists can be restored easily. A handy tip.
I like to cover my big wire lugs with clear heat shrink, so
that I can stick a label inside. Each wire is labeled,
so I can tell what the other end is connected to.
This should be waterproof.
There's an interesting gotcha with this:
If the fuse actually blows, it'll fry the alternator and voltage regulator
because the field wire from the regulator will be outputting voltage, but
the alternator will be suddenly disconnected, creating a huge voltage spike.
After some research, I read that this can be avoided
by having the field wire run through a relay that's tied to the fuse.
I decided that was needlessly complex. Someone pointed out to me that if this fuse blows there's a high probability that the entire system is already fried. Why add all that complexity to a critical wire like the field wire, that control alternator output and must be 100 per cent reliable? So I put this 200A fuse in and called it a day.
It's 200A because this fuse really should never blow. Frankly, the only way it can blow is if the current is flowing backwards from the house bank directly to ground through the alternator. The battery bank fuses should blow before that happens. But, ABYC specs call for it.
Once I know everything's working, I'll cover the wires with spiral sheathing.
Of course, stealing the boat wouldn't be that simple.
The purple wire also feeds these
bus bars next to the engine panel. I installed them a while back
when cleaning up the wiring.
The idea here is to have a clean, switched positive and ground source for items that need to be on the engine power harness. If one isn't careful, one can accidentally tie the start battery and house batteries together through the engine wiring harness. This avoids that potential problem.
The bus bars allow me to add things, like
to the engine power harness without risk.
I put a 200A slow burn fuse to protect the line coming from
and covered everything up so I don't fry myself with an exposed wire.
What I really want is a switch that would let me use the
house banks to start the batteries if needed, without tying them together.
In other words, A *or* B,
but not A *and* B.
Well, this will have to do.
If the starting battery is shot, tying them together will
make the house bank start draining into the start battery to try and achieve
balance, right at the moment when one wants all available power to start the
On top of that, the house bank might already be half drained.
I got the biggest switch I could find. It'll be set on
"start" 99.99 per cent
of the time, so I don't think I'll wear the internal mechanism out by flipping it around.
Current "Best Practices" for wiring systems frown on A/B switches.
This is the backside of my 15 year old Ample Power alternator.
It's been a pain to wire, because I have no manual for it, and the folks at Ample Power said "wow, that's a very old alternator. I don't think we have any documentation on it."
There was no point pushing, because it *is* a very old alternator. Having an external wire with a Diode going to the ground is interesting. Maybe that's Ample Power's 1990 version of a Zap-Stop thing. I just hooked it up the way it was hooked up before, and hoped for the best.
It gave me no end of fits, and just as I was starting to research new alternators I discovered a bad connection from the shunt to the voltage regulator. The wire must have come loose when I installed the big battery wires and the A/B switch.
It would work, then stop working, then start again, and there was no logical chain of causality to give me a clue.
The big clue was the Link 2000R Monitor. When you push the "Time" button when the alternator is running, it should show the actual Amperage output, as determined by the shunt next to the alternator. The readout was either "A000" or "A254". I scratched my head, then realized that it must be an eight bit register and it wasn't being updated. With the loose wire, the voltage regulator thought the alternator wasn't on (A000) or else was outputting 254 Amps (A254) and needed to be shut down.
Once the offending connection was reseated, the alternator and tachometer started working fine, and I could calibrate the tach.
The ground from block to shunt has always been a point of concern for me. I've seen ground wires that were tied into bolts that also held engine parts on, and sometimes required a specific torque. Go figure.
For this new install, the Hurth V Drive had some tapped holes that didn't do anything at all. Maybe they're for an option when the drive is used in a different kind of boat.
So I used one. I used my Handy Dremel Tool to make sure
the paint was gone from the contact point.
Of course, they required metric bolts in a length that weren't easily available. Of course.
Speaking of the wiring harness. I really considered cutting all those wires and shortening them down.
But, that would add a bunch of butt splices right in the middle of some of the most important wires on the boat.
I know how to make a perfect butt splice, all heat shrink protected and everything, but why tempt fate?
So they're coiled up and tied down securely up next to the panel, out of the way.
There's also a second harness for the idiot buzzers. It's right next to the panel and can be heard just fine from the cockpit. This is also five feet away from my berth.
McMaster-Carr carries big spools of
fire-retardant spiral wrap.
As I'm getting things finalized,
they get wrapped.
Here's a pic of the engine wiring harness.
I put "Dual Senders" on the engine,
for both Oil Pressure and Temperature, because I'm putting a second set of
the Nav Station. That way, when someone else is at the helm, (or when I'm motoring on autopilot while sitting under the dodger,)
I can see the guages.
To the right is the Dual Sender for engine
temp. It forced me to move the idiot buzzer sender over, where it interferes
with the oil fill cap.
The dual sender for the oil pressure looks just like any sender.
Here's the back of the cockpit panel.
Purple is the ABCY color for ignition switch wires, so I
added two purple wires. I pulled all the wires that were connected to the
output side of the key switch, and replaced them with a single big purple
wire that goes to
a second key switch inside the boat.
I can leave the key in the panel all the time
(or even replace it with a simple lever switch)
but when I really want to disable the panel,
I can flip the secret key switch inside the boat.
Of course, if you've read this, now you know how to rewire my panel to bypass the second switch and steal my boat.
The second guages are tucked into the panel in the Nav Station.
I didn't want to waste good mounting space for new instruments, so I just
tucked them in there above the GPS display, under the TV antenna amplifier.
The whole idea is to glance over when in the area
and make sure everything's okay.
It'll save me having to constantly ask the helmsperson "Hey,
what's the engine temp." I'm probably the only person in the world who's
constantly worrying about engine temp, and it might have something to do with
the two cars I lost in my youth.
(Both of which blew up when someone else was driving.)
I just know from personal experience that overheating an engine will create a huge disruption in one's life.
Also, problems with oil can create huge problems in one's life.
Thus the extra guages.
Well, I think there's a good reason for A/B switches.