Rewire

[Marshall Wright]

Greetings,

I need a guru. I need a boss to hold my hand thru the process of designing, laying out an upgraded electrical system and sizing the correct components and supplies needed. I've read Sailboat Electrics Simplified and Boat Wiring 101 but they don't really tell you what to do, how to layout the various components, how to size them, or how close to locate them.

Is someone willing to offer some suggestions on layout, connections, panels, etc.?

I'm not planning on rewiring the boat at this time. Most everything appears to be working fine; cabin lights, old navigation lights and everything on the mast - a decklight, steaming light, anchor light and tri-color. What I do need to do is to upgrade/modernize everything between the alternator, two batteries, a new battery selector switch and a new panel with breakers. I believe that I need to install both a + and - bus near the batteries? Should these be epoxied to the nearby hull or plywood bulkhead? And then make my connections to and from the batteries and panel through them? Or can I buy a panel that includes these busbars? I currently have over 10 positive and negative connections tied to the battery terminals. Some like lighting needs to lead to the panel while my radio, GPS and autopilot are wired directly. There is no isolation fuse between the alternator and batteries or between the batteries and the existing panel. The existing panel doesn't even have fuses. Don Casey has some suggestions on how to wire everything up if starting from scratch. I'd like to follow that advice.

If I posted a schematic would folks give me a crit and suggestions?

Marshall

[suntreader]

Hey Marshall,

I can't claim to be a guru but I can try and help. Can you tell us what kind of boat you have (I don't know everyones boat yet), type of the two batteries and whether they are tow equal banks, a single bank, or a set of starting and house batteries?

First off you don't want direct connections of the load to the battery. You are on the right track with the bus bars. You'll need a positive and a negative bus bar. If you have a small locker with the switch panel you can dedicate to wiring that is the best option. You'll want the bus bars close to the batteries, and switch panel. Between the positive bus bar and the positive battery lead you'll want to put a fuse large enough to handle all the expected loads, followed by a battery on/off switch.

The positive bus bar has connected to it: the positive from the battery, alternator output, switch panel feed, and the engine starter. Something like this:

http://www.discountmarinesupplies.com/T ... BLOCK.html

You can also get bus bars with two sides for both positive and negative on the same physical object (but electrically separated into two bars) and ones with covers. I would think covers would be a good idea. Anyone ever had to jump a starter with a screw driver? We had to do this over in the Bahamas when our starter solenoid went out, melted the screw driver.

The negative bus bar gets the negative from the battery, the grounding cable to the engine, and all the grounded wires coming back from fixtures. You can set up a high-amp ground bar and then run that to a smaller bus bar with more terminals for the low loads. In any case you don't want to double up terminal connections anywhere in the system, so make sure there are enough bus positions for everything! If you need more, add another bus bar.

It sounds like you need a new switch panel as well since the old one doesn't have any circuit protection. You can pick up a six gang panel for about $25 that will have fuses, it will also serve as your positive distribution bus for the switched items.

While the switch panel provides switching and protection for those items you want switched you still need to provide some sort of circuit protection for those permanently wired accessories that have their own power switches. The way to do that is with a fuse block, if you get one with a built in negative bus then you can wire all the accessories to their own fused positive buses and negative buses in the same box, pretty slick.

Basic type switch panel here:

http://www.discountmarinesupplies.com/S ... ANELS.html

Here is a fuse block, a pretty nice one with cover, labels, and available negative bus:

http://www.discountmarinesupplies.com/T ... BLOCK.html

There are a lot of different way to configure battery banks, switches for said banks, and the like. I'll suggest how I like to do it, but there are lots of different configurations which all work pretty well.

The set up I like is one large house bank with a single on/off battery switch in line after a whole system fuse on the positive battery lead on the way to the high-amp distribution. There isn't any complex switching to worry about and the wiring is simple. The downside is if I drain the bank until dead I can't start my engine. This situation hasn't come up yet, though admittedly I'm not exactly an old salt. Basically I load up on battery capacity, like the 300 amp/hr bank I had on my 27 footer that was used for the VHF, fluorescent light and tiny fans. We didn't run the engine for over a month and still had light to play cards by. I prefer to have enough over capacity that I'm not really ever worried about draining it all down. No separate starting battery, no combiner, very simple; it just takes paying attention.


If you could post a schematic that would certainly help. As far as sizing goes, we'll need to do some figuring, so let us know the types of gear you have.

Dave

[LazyGuy]

Marshal,

I just did the exact same thing to my Luders33. The boat came with an electronic power management system that worked great until it broke. To replace the entire system would have cost over $2000 plus it was 10 times what I needed for my coastal cruising.

I read at least three books on electrical systems and ended up using the white paper from the West Marine catalog. They have a great two page white paper saying you should use three separate switches rather than the ubiquitous on-off-both switch followed by three pages of on-off-both switches.

The boat already had three busses (one positive and 2 ground) and by the end I had added one. I have a power point slide that I can send you that shows my electrical system. I have a Balmar 3 stage regulator, the three separate switches and a 2 bank battery charger. The charger and regulator are the most expensive pieces (except for copper cable as of late).

[Tim]

First off, consider a battery combiner. This isolates your starting bank from the house bank at all times, but allows it to be charged automatically whenever the alternator is running. In an emergency, you can also use the house batteries to start the engine. The days of switching 4-way battery switches around every which way to keep your engine battery charged up are long gone. Better systems exist and are the norm now.

For example, check out this system from Blue Sea. This system includes an automatic charging relay (combiner) and a 2-position switch that is clearly marked. This is designed for a 2- bank system: engine and house. It's a clean, simple setup that will do exactly what you need. Small boats don't need more than 2 banks, no matter how many house batteries there are.

Link: Blue Sea Dual Circuit System



Here is a schematic of the battery cabling required for this system. It's straightforward. (Please ignore my handwritten notes and scribbles, which don't apply here.) This system shows one separate buss for the negative grounds; you don't really need more than this for most simple systems, but that all depends on what you're going for.



Get a new service panel that's large enough for what you want to do. More space is better than less space. Get all those extra conductors off the batteries; you should have only battery cables running to the batteries. If you need any "always hot" leads, such as for an automatic bilge pump or the memory function on a stereo or some such, run a wire from the hot side of the battery switch (that's the terminal where the cable that runs to the battery attaches) to a separate buss, and then wire the appliance to that buss as needed. Or, if you have only one such lead required, simply run that wire to the hot side of the battery switch.

Beyond these basics, there are far too many variables at hand to offer much in the way of specific advice. An exact system that worked for anyone else isn't going to do you much good, since your setup is different to begin with and you likely have different needs; each boat is individual, and the manner in which one wires it is also individual. A completed wiring system can be complicated when you look at the whole, but it's very straightforward to install when you approach it one wire at a time, as long as you know the basics of what you are trying to accomplish. The more organized you make the system, the easier it will be to maintain and troubleshoot down the line.

Basics: Use quality materials. Don't cheap out; do it right. Protect your wiring from chafe. Protect your terminals from moisture. Tie up the wires neatly to protect them and keep them out of the way. Install no more than 4 conductors on any single terminal stud; fewer is better. (This is where extra busses often come in to play.) Keep the wires out of the bilge. Make your wiring runs neat. Don't use automotive or household wiring or wire nuts. Don't use electrical tape. Buy quality adhesive-lined heat shrink connectors and learn how to crimp properly. Use the right size ring for the terminal stud. If you're a solderer, remember that solder should never be the sole means of connecting wires according to ABYC.

If you need the ABYC standard for electrical wiring, let me know, but most of that is overly complicated for what you need, and will only confuse the issue. I covered most of the applicable basics above.

You may find that it's simpler to just start over, depending on the condition and complexity of your existing wiring. Things often make the most sense with a fresh start, but if you can sort out what you have and work with it, that's fine too.

Just start. You don't need a full system schematic to begin; fancy drawings won't get you anywhere. Any individual components, like a battery combiner, will come with their own schematics for how that particular item needs to be wired; beyond that, you have to know in general what the wires are doing as you run them, but if you don't know a drawing isn't going to help. You're going to find a need for supplies you don't have no matter how well you plan, so don't try to have everything. Do your best.

It's not nearly as complex as wiring diagrams and some of the readings (such as this overlong post) can make you believe. Depending on your requirements for the system, you can keep it extremely simple without a lot of extra busses; though remote busses are handy as the system grows in complexity. Again, what works in one case isn't always the best bet for another case. Often, the simplest system you can envision is the best way. (Usually, in fact.)

Enjoy it! Wiring is fun, and is one of my favorite parts of a project. Make the system your own, following only the basic guidelines for a quality and effective system, and enjoy and understand the process as you go.

[LazyGuy]

Tim,

Well said (as usual).

[Ceasar Choppy]

The only bits that I would add to everything that has been said is that although there seems to be a real lack of good diagrams for these things, I've come to learn that there are many differing opinions on battery wiring. That and every boat is different of course.

Armed with the basics though, it might make sense to diagram it out. That and a lot of staring at various compartments in the boat to figure out what makes the most sense. I did this a couple of years ago when I completely re-wired. I find even now, two years later, I'm making changes to the battery wiring.

When I re-wired I also came to the realization that the breakers on the panel for the house loads are there to protect the wiring and not the equipment. Therefore, I planned out an effective way to have everything on its own fuse in addition to the breakers on the panel. I used the Blue Sea fuse panels, placed in strategic locations for this and it worked out great-- mostly because if I want to add something later, I just run the wires to the fuse panel instead of all the way back to the panel.

[Marshall Wright]

Everyone. Thanks for the advice, photos and, most importantly, the confidence boost that I can do this.

Unfortunately, no sooner did I post that work went into overdrive. Denver next week and Savannah the week after. But I am going to the boat this weekend to winterize and will take some photos of the panel, lazarette area that holds the batteries, existing battery switch and size the battery.

Thanks to everyone who has responded, especially Ryan for the offsite comments and suggestions.

I will get back on this as soon as time allows and it becomes really cold, perhaps with some ice on deck, so I can really suffer ...... No pain, no gain? Will post some photos of critical areas, a scan of a schematic or two and a photo of s/v Sunset dozing on her lines.

Marshall