Battery to Fuse panel routing? Fuse values?

[Inquisitor]

I apologize if there is the answer somewhere in here, but didn't find it when searching. We just got a 2005 26M recently (3rd owners) and we have been going through it cleaning, testing and replacing things.
Testing the electrical, there was no power to the fuse / switch panel. Clipping a battery charger on the bus behind the panel, I was able to test things out (lights, stereo...etc).
We have 2 batteries with the typical 1, 2, both, off switch but no connection to the fuse panel. I understand there should be a fuse between battery and the panel, but haven't found it yet, and unsure where the power cable runs. I was able to feel 4 or 5 cables running down the port side behind the panels, but tracing the main is hard since everything behind the panel is very tight.
So my first question: Does anyone have an idea where the main power connects? It goes to the back of the boat somewhere, but seems it's under the ceiling panel/cockpit floor. I'm temped to just connect directly to the battery, but if it's just a simple fuse or connection that would be best. I just can't seem to find it.
Also, I blew 2 fuses - a 6A to lights (polarized backward for LED swap) and a 5 amp to Instruments. I'd guess instruments would be better with a higher rating and their own inline fused wire. Lights maybe a 20 amp since it seems our stereo (which has a 15 amp fuse already in it). Did these boats originally have low amp fuses or could this be a previous owner fix?

Thanks,
Tom

I did see this diagram, thanks to whoever posted it, this is how mine is pretty much hooked up from what I can see.

I did the sketch viewtopic.php?f=8&t=28020&start=30#p349319 above while I was re-doing my 2007 M as some have said... things don't make obvious sense... at first.

• Mine had an in-line fuse right at the battery. Don't recall what it was.
• I believe it was 20 amp. This would make sense, since the stock interior bulbs use 1.5 amps each. The nav lights probably somewhat more.
• That battery wire goes directly to the panel. No intermediate "connections". The wire travels to the transom, then behind the liner and on to the panel. It may seem odd and a total waste of wire and a huge voltage drop... and it is a huge voltage drop especially if you start running more than stock lights! If your radio actually draws 15 amps and with all stock lighting running, you should get a voltage drop at the panel of nearly 2.5 volts... meaning your electronics will only see 10 volts. Possibly detrimentally!
• It goes to the transom because there is no other structure/cosmetic panels between the two points to hide the wire. One forum individual user ran it up the SS ladder post which shortens it to about five feet. The factory didn't do this because it is a wear issue that may short as it runs next to un-deburred SS edges and three SS bolts. Vibration and sharp edges will eventually wear and short with high amperage... size of in-line fuse!
• If you're really running that kind of amperage (like I am) you really need to find a shorter path and/or use far higher gauge wire than the 14 AWG that was in my boat.

[pleb222]

Hwy, for the stainless steel ladder routing, I was able to route the wire in a flexible tube, the wire is very well protected. The large size of gauge used and the short run means not much heat generation. I'm pretty confident in my setup

[Inquisitor]

Hwy, for the stainless steel ladder routing, I was able to route the wire in a flexible tube, the wire is very well protected. The large size of gauge used and the short run means not much heat generation. I'm pretty confident in my setup

Hope I didn't sound like I was dissing your idea. I think it was real savvy. I just don't think the factory did it for the reasons stated. Doing it properly (like I'm sure you did) takes too much time and there is still some chance someone screws up and/or the company gets sued. We get to do all kinds of things that the factory can't or won't.

[OverEasy]

Hi All

There were in the 1970s-1980s-1990s and into the early 2000s a sort of a lack of standards in what was/was-not acceptable in boat wiring ....

Seems there were several different levels of guidance with a lot of deferral to the manufacturer hence that may be the variety of things we get to deal with. This applies to 12 VDC circuits.

Eventually SAE (Society of Automotive Engineering) standards were adopted by most of the regulating and insurance entities as the guidance or at least the basis for their 12 VDC electrical stuff.

Legacy it appears was OK with a short run from battery(s) to fused (or circuit breaker) switch panel as the ‘reasonable’ expectation was a short was going to happen in the load circuit rather than the getting to the panel.... This was ok when talking about a foot or two. Most Outboard Engines I guess were assumed to have their own fuses if they had electric start and DC power generation capability.... Longer runs have greater exposure risk.

Some recognized the risk of longer runs directly from the battery and added a fuse right off the battery(s) like the Automotive market has done for a long time. The ‘battery(s)’ fuse rating is dependent upon wire size and on the run length from the battery(s) to the panel. If there are multiple wire sizes involved it defaults to the smallest wire gauge and longest run.

So the answer is “it depends”...

What are your wire gauges, the run length and the anticipated load (if a panel then everything on) at the load rating of the fuses (or breakers) installed. Not just what you have running on it at the moment. If the fuse (or breaker) is higher than you need then lower it down.

Don’t forget to verify the wire gauge and run lengths of the individual loads to determine if the wire size is adequate to the actual circuit load.

[tegwilym]

Thanks, this is helpful. I do need to add a larger fuse somewhere also since the stereo (has a 15A fuse - although should draw that much), all the inside lights and the 12v outlets are on that same circuit. I'm thinking maybe a 15 or 20 amp for that. The stock wiring is simple, but just can't find where it runs.
I've got both panels on the inside transom wall removed and have looked around but can't find the power cable back there. I assume there is maybe a fuse on that too that could be a simple fix for the lack of power at the fuse panel - but I just can't find it. I fear it's between the ceiling and cockpit floor, at least that's where I can feel some wire going to but can't identify it. *Ugh!*
Fall project for sure re-doing this mess!

Tom

I did the sketch viewtopic.php?f=8&t=28020&start=30#p349319 above while I was re-doing my 2007 M as some have said... things don't make obvious sense... at first.

• Mine had an in-line fuse right at the battery. Don't recall what it was.
• I believe it was 20 amp. This would make sense, since the stock interior bulbs use 1.5 amps each. The nav lights probably somewhat more.
• That battery wire goes directly to the panel. No intermediate "connections". The wire travels to the transom, then behind the liner and on to the panel. It may seem odd and a total waste of wire and a huge voltage drop... and it is a huge voltage drop especially if you start running more than stock lights! If your radio actually draws 15 amps and with all stock lighting running, you should get a voltage drop at the panel of nearly 2.5 volts... meaning your electronics will only see 10 volts. Possibly detrimentally!
• It goes to the transom because there is no other structure/cosmetic panels between the two points to hide the wire. One forum individual user ran it up the SS ladder post which shortens it to about five feet. The factory didn't do this because it is a wear issue that may short as it runs next to un-deburred SS edges and three SS bolts. Vibration and sharp edges will eventually wear and short with high amperage... size of in-line fuse!
• If you're really running that kind of amperage (like I am) you really need to find a shorter path and/or use far higher gauge wire than the 14 AWG that was in my boat.

[pleb222]

For the battery side fuse, be sure to add something that won't arc. A tube glass fuse is no good for this, you need a proper ANL or terminal fuse or other similar product. There are some push breakers that are rated for this. Blue sea systems has lots of good info on their website

[tegwilym]

Does anyone have an idea where the fuse on the positive lead from the battery to the fuse panel is located? I'm suspecting (hoping) that is the part that is preventing power from getting to the fuse panel. I just can't find it, or find any terminal in the back of the boat to the main battery cables where this thing connects.
To be honest, I'm really getting annoyed with the crappy workmanship from the factory on the boat. Don't get me started on the rigging that's another topic I'll be complaining more about in another thread.

Suffering buyer's remorse....

Tom

The fuse here off the battery - where is it?!!?

[Inquisitor]

Bought my new. The fuse was right at the battery... maybe 6 inches. It was just a simple in-line plastic fuse case.

[Inquisitor]

Does anyone have an idea where the fuse on the positive lead from the battery to the fuse panel is located? I'm suspecting (hoping) that is the part that is preventing power from getting to the fuse panel. I just can't find it, or find any terminal in the back of the boat to the main battery cables where this thing connects.
To be honest, I'm really getting annoyed with the crappy workmanship from the factory on the boat. Don't get me started on the rigging that's another topic I'll be complaining more about in another thread.

Re-reading your posts... The stock M from the factory does NOT include the battery cables to the engine. Mine had a simple 14 AWG Marine / tinned cable with the in-line fuse as previously mentioned at the battery location going to the transom and then to the panel. No other splicing into this line exists. The people that installed my engine supplied a separate very large gauge cable for starting the motor. This was added to the same battery. Only one battery comes from the factory. Since yours does not follow this... it is NOT stock and no one is going to be able to "see" were yours differs if you can't find it... except the owner that made the modifications.

Suffering buyer's remorse....

Tom

The fuse here off the battery - where is it?!!?

Considering how much demand there is, I'm sure there are plenty of people that will appreciate your M and pay dearly for it.

[neleus]

My wife and I bought a 2007 M about a year ago and did a rewire of the electrical system as one of our first modifications. We wanted to fit a large solar panel and increase the battery capacity.

I have a background in electronic engineering and was quite impressed with the existing wiring, most of which was obviously original - consisting of doubly insulated twin tinned copper cables of decent size. My experience has been that most older trailers/caravans/boats bought second hand will need re-wiring to some extent - and I was pleasantly surprised with the MAC.

The original (as we bought it) battery wiring went straight to the isolation switches and then via a small fuse panel (not original) up to the cabin switch panel via the ladder tubes. We added 100A fuses before the isolation switches, as close to the house batteries as possible. The starter battery really has to connect directly to the motor (also via an isolation switch) because of the large current draw when starting.

Richard

[tegwilym]

My experience has been that most older trailers/caravans/boats bought second hand will need re-wiring to some extent - and I was pleasantly surprised with the MAC.

The original (as we bought it) battery wiring went straight to the isolation switches and then via a small fuse panel (not original) up to the cabin switch panel via the ladder tubes. We added 100A fuses before the isolation switches, as close to the house batteries as possible. The starter battery really has to connect directly to the motor (also via an isolation switch) because of the large current draw when starting.

I wonder if something changed between our 05 and your 07? I only have 2 thick cables from the batteries (and the selector switch) that run to the back of the boat and go into the engine. There is nothing from the main battery to the fuse panel, I'd expect it to be on the switch, but nothing there. Is it reasonable that it meets at the engine? That seems stupid though. The cables themselves seem ok, but the routing of it is a joke (at least on an 05 model).

Tom

[neleus]

Just re-read through all the posts.

One note - our 2007 M has a (original) negative bus bar in behind the cabin switch panel - not just a bolt. I know it's original as it's a custom made job It's quite serviceable though and I've retained it for the moment.

I feel your pain with tracing the wiring, been there - done that.

Our main wiring paths were/are:
- Cabin switch panel to cockpit pedestal - via port side down between the cabin liner and the deck then across under the cockpit to the pedestal access hole (joining a bunch of other wiring including the motor electrical control connections).
- Cabin switch panel to battery isolation switches - across between the cabin liner and the deck and then down inside the ladder tubes (probably not the original route).
- Cabin switch panel to mast area and forward - across between the cabin liner and the deck past the cabin access ladder to the starboard side then forward to the "compartment" under the starboard side of the mast (where our stereo is mounted and the connections for the mast wiring are located) between the cabin liner and the hull (you can feel the wires if you push your hand up under the cabin liner above the dinette table)
- Starter battery to motor - in the "bilge" down the port side under the rear berth

It seems likely, given what others have said, that your wiring for the main feed to the cabin switch panel is routed from the motor or the ignition switch - so connected at the motor itself, or in the pedestal. The wiring would not be obvious if it was fed from the stern up between the cabin liner and the deck. If it's connected at the motor, then it could have become disconnected when work was done on the motor - or an inline fuse could have blown. If the connection is inside the pedestal then similarly there could be an inline fuse which has blown.

Hope this helps.

Richard

[OverEasy]

Of the final items completed was our Battery System Manual Reset Circuit Breaker. We use a single breaker between the “USE” Selector Switch and the boat distributed systems including the 50 HP 2001 Tohatsu Engine.

It is a 60 Amp manual reset circuit breaker with sufficient capacity to handle starting our engine and adequately protecting our vessel distributed loads. (Note: We also have all our distributed loads on individual manual reset circuit breakers and switches.)




Hopes this helps some in your planning.

[tegwilym]

Good idea! That breaker looks familiar. Same thing on the back wall of our Ford Expedition that seems to have a bad connection there on the breaker when winter temps get down below -10F in the winter.

Tom

It is a 60 Amp manual reset circuit breaker with sufficient capacity to handle starting our engine and adequately protecting our vessel distributed loads. (Note: We also have all our distributed loads on individual manual reset circuit breakers and switches.)

[OverEasy]

Just a suggestion on your Ford Expedition...

Look at the connections carefully, you will find that the connection has corrosion or a poor crimp joint.
The cold contracts and pulls a connection to be intermittent.
Start at the breaker and methodically work your way through the immediate connections to make sure not only the blade/socket are tight but also the wire crimps and connector rivets.

Then work your way down the wires.

I’ve used these breakers in some wet (submerged) and extreme environment conditions both hot (100+) and cold (-20) without incident.

One way you can thermally cold stress the actual device is with a pure CO2 fire extinguisher.
It might be that your particular device has an internal contamination.
I don’t believe that the Ford automotive breakers are sealed units and moisture/dirt may have compromised it.

Again, just a suggestion.