Wiring Options - I Need Lots of Help !

[Jon Neely]

Ok here is the deal and I need some ideas and for our new boat, we have completely gutted the wiring and am starting over. I have some basic ideas but I would like to hear what else you guys and gals could suggest. As of right now I want to go with 3 house batteries and one cranking. I have a 16 switch panel and one single perko 3 switch battery. As of now I have a 1000watt inverter/charger sine. And lots of ul grade marine wire. Any more Ideas are great. I have questions about battery regulators, fuses(where to put them) Dual-Battery M-Series Distribution Panel Dual-Battery M-Series Distribution Panel

Hit me with it!


Thanks,

Jon

[daddle]

Fuses? Ugh!

[Jon Neely]

I have breakers built into my new bluesea panel.


Jon

[Charlie]

JOn:

that is a pretty in depth question. You may need fuses in addition to the circuit breakers to protect individual items such as GPS VHF etc. The first thing to do is an energy audit figuring out how much power you will consume. From there you can figure out what batteries will suit what you need. Then you can figure out your charging system. Amazon.com: This Old Boat (9780071579933): Don Casey: Books is a good book to help you get started.

[Jon Neely]

Well the batteries I have always used are gruop 27 deep cells:
Battery Type: Lead Acid / Wet / Flooded
Voltage: 12
Cold Cranking Amps : 680
MCA: 850
Amp Hours: 100 minutes
RC: 170 minutes

[hellosailor]

John, you will find the "new" systems, for 20+ years or so, all require installation of fuses or breakers directly at the batteries, not just in the panel. High power breakers, that won't arc shut and fail under a high load, are damned expensive so typically you would use fuses on the batteries themselves.

When someone drops a wrench against a cable or something equally simple and brutal happens, even a group27 battery can put out over 3000 amps into the dead short, and that's more than the usual breaker (or your wiring) can deal with.

Ideas? Neat, restrained, labelled, and proper marine grade terminals and connections all over.

[clearsea]

Some suggestions: Look up the ABYC specifications www.abycinc.org/. Pick up Nigel Calder's latest edition of Boatowner's Mechanical and Electrical Manual. Make an amps budget for all the electrical components on the boat. Develop schematics for the charging, ignition, engine and house systems and get them reviewed by a marine electrical engineer. Check out the information on the Blue Sea Systems website, and use their calculator at Blue Sea Systems to run some simulations. Read Maine Sail's website on making proper electrical connections, and check out the recent Practical Sailor for an article on that topic.

[osirissail]

Raw basics in marine electrical systems are covered nicely in Nigel Calder's book which is well worth the price.
- - Big differences between marine/boat wiring and any other wiring is be sure to use Marine Wire which has a different number of strands than other wire. Tinned stranded wire is the best.
- - All connections are made with "terminals" which are ring eye metal terminals that are attached to each items and panel by small machine screws. This is to prevent wires from being pulled loose during boat movement.
- - All circuits (a wire going to a load/item) must be protected by a circuit breaker rated no larger than the carrying capacity of the size wire being used.
- - A new item is that each battery source (one or more batteries connected together) needs to have a "bus fuse" rated to the size of the battery cables connected up close and personal to the actual batteries. From this "bus fuse" then your battery cables go to the main power panel or the engine starter.
- - Another new items is that major power items like inverters and chargers need to have a fuse at the charger/inverter end of the cables between the item and the main distribution panel.
- - All of this is based on protecting the pieces of wire connecting anything from being subjected to more amperes than the wire is rated to carry. If your shove 100 amperes down a 15 ampere rated wire it is very likely the wire will catch on fire. Which is a nasty thing to happen when you are sailing out of sight of land.

[foggysail]

I just installed 2 battery banks with fuses. I forgot where I read the requirements but from what I remember fuses are required to be within 18" of teh battery.

A couple of good comments were made above about being able to break an arc along with possible breaker cost. DC is very difficult to break!!! For example, with AC, the current will pass through 0 amperes at twice the frequency rate. That helps a great deal to break an arc.

The next comment I want to make regarding DC is no matter how one tries, there is inductance in the circuits where load currents flow. What does it mean??? Remember, one cannot stop current in zero time in an inductor. The current will continue to flow regardless of the voltage needed to make it flow, just like an ignition coil. I don't wnat to get further into this because most who will read it won't know wht the heck I am referring to. But this is elementary circuit theory and one should be very careful dealing with batteries.

If you short out battery terminals, you will never forget the event!!!

Foggy

[knottybuoyz]

Originally Posted by foggysail

I just installed 2 battery banks with fuses. I forgot where I read the requirements but from what I remember fuses are required to be within 18" of teh battery.

ABYC E-11.12 Overcurrent protection is required within 7" of the battery unless it's a primary conductor in a conduit then it's 72".

A couple of good comments were made above about being able to break an arc along with possible breaker cost. DC is very difficult to break!!! For example, with AC, the current will pass through 0 amperes at twice the frequency rate. That helps a great deal to break an arc.

Originally Posted by foggysail

If you short out battery terminals, you will never forget the event!!!

Absolutely!

[SailFastTri]

John this is a huge topic, and mistakes could cost you your boat -- or maybe even burn an entire boatyard.

You seriously need to do a lot of reading (as in read a book that covers the marine wiring subject in-depth; with pictures, diagrams etc). You won't get the organized and in-depth knowledge you need from discussion group tips.

Plan B is to hire a pro to do this.