Carbon monoxide (?) mystery

[tonywright]

That was my reaction to the 0/1 too Jon. The stock wire on mine is probably 12 or 10. I did note that Xantrex recommends 4 or 6, which appears to be tied to the amounts of amps it can produce.  I would imagine that it would be hard to wire a fuse in line to 0/1. Like Michael, I am very much in learning mode on this.

On the subject of identifying the gas that set off the alarm, I asked my neighbour, who is a fire chief, whether the fire dept had the necessary equipment, and whether they would have come to test had you asked. His reply was very affirmative. They would far rather help you avoid a problem, than come out after something serious happened. A fire dept in a large city is almost certain to have the necessary test equipment to identify the gas involved. Worth remembering. (I am sure that Aunt Gertrude would approve.)

Tony

[Michael]

Jon/Tony:

Hali came equipped to us with the heavy (1/0 gauge) wires between the battery charger and the batteries.   The cable runs are less than six feet, from the charger beneath the built-in garbage can to the battery boxes beneath the aft settee in the salon.  My hunch was that any possible power draw (from charger to battery or vice versa) could not exceed the rating for that wire, so there would be no fire hazard if we dispensed with fuses or circuit breakers.

But doubting my hunches might be good policy:  I blew a fuse on my new Fluke multimeter last week.

Yours is an interesting point, Jon, that the other purpose of the fuse or circuit breaker is to protect the Xantrex XC3012 itself from, I suppose, a surge of power from the batteries.

For what its worth, a posting in an electric vehicle discussion (at http://www.evdl.org/archive/index.html#nabble-p17725445)(found on a Google search and of unknown authority), indicates that 1/0 gauge wire is rated to support up to 120 amperes in a cable run of 120 feet at 60 degrees centigrade with a 1-3% drop in voltage.

Am I correct in thinking that in calculating the possibility that a surge of power from the batteries might overheat the wire or damage the XC3012, we would assume the possibility of a dead short drawing the maximum current over a short period of time through the wire and into the battery charger?  And therefore, that we could look to some short term output rating (cold cranking amps?) for the batteries (flooded lead acid Interstate 4Ds) to determine whether the wire rating or amp rating for the battery charger might be exceeded?

Now that I begin trying to figure this out, it begins to seem like a better and better idea just to follow the Xantrex suggestion and put a fuse or circuit breaker into the lines.  Do you think that I would be right in taking the Xantrex XC3012 30 amp rating as the appropriate figure and using a 30 amp circuit breaker? [Later edit: no.  See Jim Moe tech note cited by Stu Jackson at post #62 below and see post #63.] (It seems to me that that the rating for the 1/0 gauge wire being substantially higher, the "weak link" would be the battery charger itself and that the circuit breaker should therefore be selected with protection of the battery charger in mind.) The slithering sound you hear is me skating here.

Regards.


   

[Stu Jackson]

Michael, why not keep it simple and not reinvent the wheel.  Jim Moe's electrical system design, here: http://www.c34.org/projects/projects-electrical-system-upgrade-2.html  discusses the ABYC fuse requiremens and includes sizing for your application.  It could also be that your charger installation manual includes that requirement - our Freedom 15 I/C did.

[Michael]

Stu, thank you for the reference to Jim Moe's article.  From that article, which touches on all sorts of good things, I take away relevant to the current situation that:

(1) fuses should be rated at 150% of the charger capacity [which I think but will check will mean a 45 amp fuse for the XC3012];
(2) the fuses can be conveniently located in the battery box; and
(3) the AYBC code requires the fuses.

Conclusion: we will install fuses (or circuit breakers) in the battery compartment on the charger-to-battery cable runs.

[Stu Jackson]

1.  Sounds about right
2.  It's not convenience in the battery box, but rather within 7 inches of the battery which si the rule
3.  yup, although many of us have lived for years without them, before the newer codes came into effect  -  I believe I covered that subject, of newer codes, in earlier discussions

[Jon Schneider]

FWIW, Michael, I came to the same conclusion you have, and installed 40A fuses in the battery case for the XC3012.  Technically less that the 150% rule, but close enough (I don't think there's any such thing as a 45A fuse), plus the tripping action is probably at least 10-20% higher than the rating.  Don't forget to buy back-up fuses.